Test for Topics Biology Form 2


TOPIC : 1  NUTRITION GENERAL

BIOLOGY EXAMINATION FORM TWO
TOPICAL EXAMINATIONS.
NUTRINAME………………………………………..CLASS………………………………………….……………TIME: 21/2HRS
INSTRUCTIONS:-
This paper consists of sections A, B and C
Answer all questions
All answers must be written in the spaces provided
All writings should be in blue/black inks except for drawings that should be in pencils
SECTION A.
Multiple Choice questions.
Below are some of diets taken in East Africa, which one of them could easily cause
kwashiorkor in children when taken for quite a long period?
Millet with fish
Cassava with beans
Rice with meat
Bananas with green vegetables
A person whose diet lacks iodine is likely to develop a nutritional disorder known
As
A. beriberi
B. rickets
C. night blindness
D. goitre.
A person with a deficiency of vitamin C is likely to become a victim of
A. beriberi
B. rickets
C. night blindness
D. scurvy.
iv) Below are some of diets taken in East Africa, which one of them could easily cause
kwashiorkor in children when taken for quite a long period?
Millet with fish
Cassava with beans
Rice with meat
Bananas with green vegetables
A food sample which was tested by boiling with Benedicts or Fehlings solution gave an orange precipitate. This showed that the food sample contained
A. reducing sugar
B. fats
C. protein
D. sucrose.
A person with a deficiency of vitamin C is likely to become a victim of
A. beriberi B. rickets
C. night blindness D. scurvy.
vii) Which part of a leaf has a large surface area for absorption of sunlight?
Petiole
Lamina
Stomach
Apex
Which of the following is not a traditional method of food preservation?
Canning
Curing
Drying
Smoking
The first site of digestion of protein is in the,
Mouth
Oesophagus
Stomach
Small intestine
Bile is produced in the
Pancreas
Stomach
Gall bladder
Liver
Matching items questions.
LIST A
LIST B
Waste excreted from the bowels
Wave-like muscular contraction that push food along the oesophagus
Connect the mouth to the stomach
Grind the food
Absorbs water from undigested and indigestible food materials.
Waste is stored here ready to leave the body
Preservation of food using honey
Break down of disaccharides into monosaccharides
Minerals which are required in very small amounts
Break down of water molecules by use of sunlight
Carbondioxide fixation
Photolysis
Macro-elements
Trace-elements
Hydrolysis
Condensation
Curing
Smoking
Duodenum
Oesophagus
Rectum
Molars
Peristalysis
Pyloric sphincter
Canines
Faeces
Stomach.


SECTION B.
3.(a)explain briefly how you would carry out the following tests
Millons test
Reducing sugar
Starch
b) Give the properties of the following food substance?
i) Monosaccharides
ii) Disaccharides
Polysaccharides
4. (a) outline the adaptation of ileum in digestion and absorption of food.
b) mention the role of the following in digestion,
i) hydrochloric acids
ii) bile
iii) saliva
5. (a) distinguish between;
i) Food preservation and food storage
ii) refrigeration and freezing
iii) curing and smoking
b) Explain how the following methods can be used to preserve food
i) Smoking
ii) Pasteurization
iii) Using additives
6. a) Name at least five vitamin deficiency diseases.
b) i)What is a balanced diet?
ii) List six components of a balanced diet.
7. a) Name the three elements that form carbohydrates. (b) Briefly state two properties of polysaccharides.
8. (a) What are the building blocks of proteins?
Distinguish between first class proteins and second class proteins.
State four functions of lipids in the human body.
9. A team of researchers went to a village near Tukuyu, Mbeya and found a five year old boy with the following symptoms:
The stomach was protruding. • The skin was dry, flaky and rough.
The hair was reddish and fell off easily. • The boy had no appetite.




(a) (1) Name the disease that the boy was suffering from.
What deficiency caused the disease?
Mention other disorders the boy was likely to be having.
What advice would you expect the researchers gave to the parents of the boy?
(b) Suggest the type of diet, which the boy may have been eating.
10. a) list two functions of digestive system
b) distinguish between mechanical and chemical digestion
c) which enzymes completes the digestion of protein in the ileum





Page 4


TOPIC : 2  HUMAN DIGESTION

BIOLOGY EXAMINATION FORM TWO
TOPICAL EXAMINATIONS.
HUMAN DIGESTIVE SYSTEM.


NAME………………………………………..CLASS…………………………………………….………TIME: 21/2HRS
INSTRUCTIONS:-
This paper consists of sections A, B and C
Answer all questions
All answers must be written in the spaces provided
All writings should be in blue/black inks except for drawings that should be in pencils


SECTION A.
MULTIPLE CHOICE QUESTIONS.
Which of the following food substance starts the process of digestion in mouth?
Protein
Lipids
Carbohydrates
Vitamins
The end product of digestion of protein is;
Fatty acids and glycerols
Amino acids
Peptides
Glucose
Which of the following digestion activity do not occur in the mouth?
Mechanical break down of food
Conversion of starch into maltose
Mixing food with saliva
Brake down of protein
Movement of food down the oesophagus is aided by;
Gravity
Peristalysis
Breathing
Swallowing
The role of the tongue in digestion of food is;
Mix food
Swallow food
Role food into bollus
Chew food.
Bile is produced in the
Gall bladder
Liver
Duodenum
Pancrease
Absorption of amino acids takes place in;
Lacteal
Blood cappilaries
Lymphatic system
Epithelium
Which of the following glands secretes both digestive juice and enzyme?
Salivary gland
Adrenal gland
Sweat gland
Pancrease
Which of the following substances is not found in the stomach?
Ptyalin
Lipase
Renin
Hydrochloric acid
In mammals, the organ that acts as a reservoir of carbohydrate is?
Pancreas
Liver
Spleen
Stomach.
MATCHING ITEMS QUESTIONS.
LIST A
LIST B
The substances that slowdown the action of enzymes.
Wavelike movement of food down the alimentary canal
Muscle valve found at the entrance of duodenum
Breakdown of fats into small droplets
Inactive form of pepsin
A structure for absorption of food
Bacteria infection of the gum
A term used to describe the infections of the teeth
A wound found in stomach
Contain secretions with three enzymes
Bile
Enterokinase
Propepsin
Pro-renin
Cardiac sphincter
Pyrolic sphincter
Peristalysis
Emulsification
Hydrolysis
Periodontal disease
Ulcers
Bacteria
Dental carries
Pepsinogen
Villus
Globlets


a) Mention the components of human digestive system
b) Give the meaning of the following terms as used in this topic
i) Digestion
ii) Absorption
iii) Assimilation
iv) Ingestion
v) Egestion
4. a) Briefly explain the role of the following in the process of digestion?
i) Teeth
ii) Tongue
iii) Saliva
b) Explain the nature of digestion that takes place in the mouth
5. a) Briefly explain how the food moves down the alimentary canal
b) Explain the adaptations of the stomach in the process of digestion
c) Mention the role the following in digestion
i) Hydrochloric acid
ii) Pepsin
iii) Rennin
iv) Mucus.
6. a) What is the work of the liver in digestion?
b) Mention four components of pancreatic juice and state their roles
7.a) briefly explain the role of the ileum in the process of digestation
b) Mention the all end products of the process of digestion.
8.a) Explain the adaptations of the ileum in the absorption of food.
b) Draw and label the structure of the ileum.
9. Discuss the main differences between the digestive system of ruminants and human beings
10. Describe the main disorders that affect human digestive system


TOPIC : 3  FOOD PROCESSING

BIOLOGY EXAMINATION FORM ONE
TOPICAL EXAMINATIONS.
FOOD PROCESSING,PRESERVATION AND STORAGE EXAMINATION


NAME………………………………………..CLASS…………………………………………………TIME: 21/2HRS
INSTRUCTIONS:-
This paper consists of sections A, B and C
Answer all questions
All answers must be written in the spaces provided
All writings should be in blue/black inks except for drawings that should be in pencils


SECTION A. 20 MARKS.


MULTIPLE CHOICE QUESTIONS.
Food processing means,
Treating food substances and make palatable and stay long
Converting food to another form
Keeping food substances in their original forms
Adding preservatives to food
Food preservation means
Treating food substances and make palatable and stay long
Converting food to another form
Keeping food substances in their original forms
Adding preservatives to food
Which of the following is not a preservative?
Honey
Salt
Organic acid
Pepper
Which of the following does not support the growthof micro-organism?
Sugar
Moisture
Oxygen
Warmth
Which of the following is not a traditional method of food preservation?
Smoking
Freezing
Boiling
Pickling
Which of the following food substance can be preserved by boiling?
Cereals
Fish
Meat
Vegetables
Baked beans can best be preserved by using,
Canning
Bottling
Boiling
Freezing
Sodas, juices and tomato sources can be preserved by:
Freezing
Boiling
Bottling
Canning
Adding flavorings in food assist in;
Making food appealing to eat
Make food stay longer
Promotes absorption of water
Improves appetite
One disadvantage of traditional methods of food preservation is that;
They are costly
Need high technology
Alter texture, taste and colour of food
It is expensive.
MATCHING ITEMS QUESTIONS.
LIST A
LIST B
Treating food in order to make them palatable and prolong their life
Keeping food for future use without getting spoiled.
Keeping food in their original form or condition and prevent it from getting spoilt.
Preservation using honey
Preservative used to prevent bacteria growth
Chemical substances added to food but do not alter nutritional value
Storing food at a temperature of below -200c
Suitable for preservation of soft drinks
Uses high technology and used in towns
Required for growth of micro-organisms.
Food storage
Food preservation
Food processing
Pickling
Covering
Water and air
Water air and moisture
Good PH
Modern methods
Traditional methods
Food additives
Freezing food
Use of fridzer
Bottling
Canning
Salt


A) Define the following terms
Food preservation
Food processing
Food storage


b) Explain the importance of food processing and preservation
4. Briefly explain the following methods of food preservation. In each give an example of food preserved.
a) Boiling
b) Smoking
c) Salting
d) Pickling
e) Drying
5. Describe the following methods of modern food preservation
i) Freezing
ii) Bottling
Canning
iv) Refrigeration.
6. Define and explain the following terminologies
i) Food additives
ii) Flavouring
iii) Colouring
iv) Bulking
v) Preservatives.
7. Outline the differences between food preservation and food processing.
8. Explain how each of the following foods can be preserved.
i) Meat
ii) Fish
iii) Cereals
iv) Cassava
v) Mango juice.


Page 4


TOPIC : 3  FOOD PROCESSING AND PRESERVATION

CHAPTER 3
FOOD PROCESSING, PRESERVATION AND STORAGE.
Defination of terms
Food processing
This is the method of treating food substances in a way to make them palatable and prolong their life without getting spoilt.
Food which can be processed includes, meat, vegetables fruits and cereals.
Food preservation-
This is the method of keeping food substances in their original state or in good condition to prevent it from getting spoilt.
We use preservatives to prevent food from being spoilts. Examples of preservatives includes honey, salt, and organic acids.
Food storage.
This refers to the methods used to keep food for future use without getting spoilt. Food should be stored in conditions which do not allow the growth of micro-organism.
Importance of food processing, food preservation and food storage
Food can be eaten in several days because it will not get spoilt.
Ensures continuous supply of food even during the off season.
Nations which face harsh winter can have food, throughout the year because food can be stored.
Allows for easy transportation of food without being spoilt and also in a convenient way.
Processing and preserving food maintains the original state of food by inhibiting growth and multiplication of micro­organisms which cause food spoilage.
Storage of food prevents the growth of micro-organism thus reduces losses which can be incurred by farmers as a result.
The growth, reproduction and increase of micro-organisms need conditions such as water, temperature and oxygen, all preservation methods ensures that these conditions are kept away and micro-organisms do not multiple and grow.
Methods of food preservation
Methods for preserving food are grouped into two main categories, namely:
Traditional methods
Modern methods
Traditional methods of food preservation
Boiling
In this method of food preservation, the food is boiled for some times, then allowed to cool.
It is then kept in an air tight conditions which will not allow the growth of micro-organisms.
This method is not very effective in preservation of food, because once the food cools, micro-organisms can enter.
Smoking.
This is the process in which food is kept over fire for a period of time so as to dry it and kill micro-organisms.
The method is suitable for meat and fish preservations.
Drying in the sun
This is the removal of water from food using heat from the sun.
The dried food creates unfavourable environment for the survival of micro-organisms, therefore food can last for many years.
This technique is suitable for food such as maize, beans, millet and soghum.
Salting
The method is mostly used in preserving fish and meat.
It involves either soaking the food in a concentrated solution of sodium chloride or sprinkling with the salt.
The salt has ability to absorbs water from the food which again creates an unfavorable environment for the micro-organisms to survive.
Pickling
This is the use of honey to preserve food. The food is kept in the honey and stored in a convenient place.
When food is pickled, it is put in a preservative like honey. Normally meat is coated with honey and stored.
Honey has a high concentration of substances such as sugars where micro-organisms cannot grow.
Did you know that honey can stay for over 400 years without decay? Now you know.
Modern methods of food preservation
This methods of food preservations depend on the high technology that has continued to be developed over the years.
The advantages of modern method is that, they do not alter the taste, texture and colour of the food much.
Advancement in science and technology has made this possible. Modern methods of preservation include:
Refrigeration
Food is kept in a refrigerator at very low temperature. The low temperature inhibits the growth of micro-organism.
This method is suitable for foods like milk, meat, cheese, vegetables and butter among others.
Canning
This method works as follows,
Food is heated under pressure to kill any micro-organisms in the food.
While food is still hot, it is transferred into sterilized metal cans.
Air is sucked out by machines and the can is sealed to prevent any entry of micro-organisms.
This method is suitable for foods like fish, backed beans fruits and fish.
Freezing


In this method, food is kept under very low temperature at -20°C.
This temperature stops the activities of micro-organism, thus enabling the food to stay for a longer period of time without getting spoilt.
The food will stay fresh as long as it is kept in freezer


Bottling
Bottles are cleaned and sterilized. After food or drink is transferred to the bottles, then the bottles are air tight sealed to prevent any oxygen into it.
It also applies the principle of canning Soft drinks such as sodas, juices and tomato sauce are preserved using this method.
In some cases a preservative is added to the drink to increase its shelf life
Food additives
Food additives are chemical substances added in food but do not have nutritional food value. Food additives include:
Preservatives
They prevent bacterial growth. An example of a preservative is common salt.
Flavouring
This promotes flow of saliva. They make food taste good and hence improve appetite.
Colouring
Colouring gives food a good colour and appeal to the one eating. Some colourings may cause allergic reactions in some people.
Bulking agents
They help to add the bulkiness to the food, for example meat tenderizers which promote the absorption of water by osmosis into the meat so that it weighs more.
Differences between traditional methods and modern methods of food preservation.
Traditional methods
Modern methods
1. Less expensive
More expensive
-- - —
Food cannot be stored for long period of time
Need low technology
Food can be stored for a longer period of time Need high technology
Somehow alter the taste, texture and colour of the food
Can be applied in rural areas where there are no services such as electricity
Do not alter the taste, texture and colour of food very much
Can only be applied where services such as electricity are available.




SUMMARY
Food processing refers to ways of treating food to make it edible, appetizing and safe to eat or to keep fresh for a long time.
Food preservation refers to the methods used to prevent food from going bad.
Food storage is the keeping of food for future use.
Traditional methods of food processing, preservation and storage include curing, drying, smoking, cooking and storing in granaries or pits.
Modern methods of food processing, preservation and storage include refrigeration, freezing, pasteurization, canning, bottling, and using additives, dehydration and irradiation.

END OF TOPIC QUESTIONS.


1. Which of the following is not a method of food preservation?
Salting
Refrigeration
Cooking
Drying in the sun
2. The main reason for keeping food in refrigerators is to make it………
Cold
Sweet
Soft
Last longer
3. A method of preservation which involves heating and cooling is …………
Smoking
Drying
Pasteurization
Salting
4. A Preservative chemical food should first be…………..
Food preservation
Food processing
Food storage
Pasteurization
5. Write True for correct statements and False for wrong statements.
During processing, a food loses some important nutrients.
If food is not preserved, micro organisms may attack it.
Drying and salting are among the modern methods of food preservation.
Pasteurization involves preserving food by keeping it at low temperature.
Cooking is the best method of preservation and storage for all types of food.
6.Write four advantages of traditional methods of food processing and preservation (2 each)


7. Fill in the blanks.
………….. is a method of food of preservation in which salt water or vinegar are used.
…………… is a method of food preservation in which food is heated at very high temperatures.
……………. Is an example of food preserved by using chemical inhibitors.
…………… is an example of food preserved by using chemical inhibitors.
………. Is a traditional method of preserving food in which food is kept in the sun to lose water.
8. Write an essay about food preservation using the following guidelines
a) Meaning of food preservation
b) Methods of food preservation
c )Examples of food preserved by each method
d) Merits and demerits of food preservation.


9. How is food preservation different from food processing?
10. Explain a method or methods you would use to preserve the following foods.
11. Explain why food should be processed.
12. Explain why food should be processed.
13. Write a letter to the editor of news paper suggesting how the food should be preserved to care for the cater for the drought season, taking into account that people should eat balanced diet.
Write four advantages of traditional methods of food processing and preservation (2 each)
15. Comment on the statement we no longer need traditional methods of processing, preserving and storing food.
16. Comment on the statement we no longer need rational, methods of processing, preserving and storing food.
TOPICAL EXAMINATIONS
FOOD PROCESSING,PRESERVATION AND STORAGE EXAMINATION
SECTION A. 20 MARKS.


MULTIPLE CHOICE QUESTIONS.
Food processing means,
Treating food substances and make palatable and stay long
Converting food to another form
Keeping food substances in their original forms
Adding preservatives to food
Food preservation means
Treating food substances and make palatable and stay long
Converting food to another form
Keeping food substances in their original forms
Adding preservatives to food
Which of the following is not a preservative?
Honey
Salt
Organic acid
Pepper
Which of the following does not support the growthof micro-organism?
Sugar
Moisture
Oxygen
Warmth
Which of the following is not a traditional method of food preservation?
Smoking
Freezing
Boiling
Pickling
Which of the following food substance can be preserved by boiling?
Cereals
Fish
Meat
Vegetables
Baked beans can best be preserved by using,
Canning
Bottling
Boiling
Freezing
Sodas, juices and tomato sources can be preserved by:
Freezing
Boiling
Bottling
Canning
Adding flavorings in food assist in;
Making food appealing to eat
Make food stay longer
Promotes absorption of water
Improves appetite
One disadvantage of traditional methods of food preservation is that;
They are costly
Need high technology
Alter texture, taste and colour of food
It is expensive.
MATCHING ITEMS QUESTIONS.
LIST A
LIST B
Treating food in order to make them palatable and prolong their life
Keeping food for future use without getting spoiled.
Keeping food in their original form or condition and prevent it from getting spoilt.
Preservation using honey
Preservative used to prevent bacteria growth
Chemical substances added to food but do not alter nutritional value
Storing food at a temperature of below -200c
Suitable for preservation of soft drinks
Uses high technology and used in towns
Required for growth of micro-organisms.
Food storage
Food preservation
Food processing
Pickling
Covering
Water and air
Water air and moisture
Good PH
Modern methods
Traditional methods
Food additives
Freezing food
Use of fridzer
Bottling
Canning
Salt


A) Define the following terms
Food preservation
Food processing
Food storage


b) Explain the importance of food processing and preservation
4. Briefly explain the following methods of food preservation. In each give an example of food preserved.
a) Boiling
b) Smoking
c) Salting
d) Pickling
e) Drying
5. Describe the following methods of modern food preservation
i) Freezing
ii) Bottling
Canning
iv) Refrigeration.
6. Define and explain the following terminologies
i) Food additives
ii) Flavouring
iii) Colouring
iv) Bulking
v) Preservatives.
7. Outline the differences between food preservation and food processing.
8. Explain how each of the following foods can be preserved.
i) Meat
ii) Fish
iii) Cereals
iv) Cassava
v) Mango juice.




MORE PRACTICE QUESTIONS
1. Which of the following statements gives the nearest biological meaning of chlorophyll?
Dark pigment found in plants.
Green pigment found in plants.
Non-starch pigment found in plants.
Yellow pigment found in plants.
2. If you buy some onions from the market most of what you buy is
swollen leaves
swollen stems
swollen roots
swollen endosperms.
3. In which main form is the product of photosynthesis transported from the leaves to the other parts of the plant?
A. Sucrose B. Glucose
C. Starch D. Amino acids
4. During photosynthesis plants require the presence of
oxygen, light, chlorophyll and water
chlorophyll, oxygen, carbon dioxide and water
carbon dioxide, light, chlorophyll and water
water, carbon dioxide, sugar and light.
5. The main end product of photosynthesis is transported away from the leaves by the
A. phloem B. xylem
C. veins D. vascular bundle.
6. Which of the following statements in not true?
Plants respire all the time.
At night plants give out carbon dioxide.
During the day the rate of photosynthesis exceeds that of respiration.
Plants only respire.
7. The following parts of a leaf have chloroplasts except one. Which one?
Guard cells
Palisade layer
Cuticle
Spongy mesophyll layer
8. An epidermal cell from a leaf was put in a hypertonic solution. After some time the cell became
A. crenated B. turgid
C. flaccid D. deplasmolyzed.
9. During photosynthesis
A. macromolecules are built from micro molecules
micro molecules are synthesized from macromolecules
heterotrophs use sunlight to produce food
saprophytes use chlorophyll to manufacture food.
10. If you go to a market and buy some Irish potatoes and onions, you will actually be buying
stern tubers and fleshy leaves
root tubers and fleshy leaves
root tubers and stem tubers
underground sterns.
11. Dark stage of photosynthesis takes place
in the presence of light only
in the absence of light only
both in light and in darkness
in a special type of light only.
12. In photosynthesis, light provides the energy to
cause photolysis
form ADP
form ATP
form ATP and cause photolysis.
13. An example of a macro-nutrient in plant nutrition is
A. manganese B. zinc
C. copper D. phosphorous.
14. Which one of the following is an example of a micronutrient in plant nutrition?
A. Boron B. Nitrogen
C. Potassium D. Iron 15.
The series of reactions in the dark phase of photosynthesis take place in the
stroma
grana
matrix of the chloroplast
cytoplasm.
16. Mostly photosynthesis occurs in the
palisade cells
spongy mesophyll cells
upper epidermis of the leaf
guard cells.
17. The following are factors that affect the rate of photosynthesis, which one is not?
Temperature
Water
Carbon dioxide
Chlorophyll


TOPIC : 4  NUTRITION IN PLANTS

BIOLOGY EXAMINATION FORM TWO
TOPICAL EXAMINATIONS.
NUTRITION IN PLANTS.


NAME………………………………………..CLASS…………………………………………….………TIME: 21/2HRS
INSTRUCTIONS:-
This paper consists of sections A, B and C
Answer all questions
All answers must be written in the spaces provided
All writings should be in blue/black inks except for drawings that should be in pencils
SECTION A. 20 MARKS.
MULTIPLE CHOICE QUESTIONS
In plants most photosynthesis occur in the;
Palisade cells
Spongy mesophyll
Upper epidermis of the leaf
Guard cells
The role of light in photosynthesis is to
Form ATP
Form ADP
Cause photolysis
Form ATP and cause photolysis
Which of the following parts of a leaf does not have chloroplast?
Guard cell
Palisade cell
Cuticle
Spongy mesophyll
The main product of photosynthesis is transported away by
Phloem
Xylem
Veins
Vascular bundles
The following are the requirements for the process of photosynthesis
Light, water, chlorophyll and oxygen
Chlorophyll, oxygen, carbon dioxide and water
Carbon dioxide, light, chlorophyll, and water
Water, carbon dioxide, sugar and light
The dark stage of photosynthesis takes place in the;
Stroma
Grana
Matrix of the chloroplast
Cytoplasm
What is the main end product of photosynthesis?
Oxygen
Water
Energy
Glucose
The rates of photosynthesis are affected by the following factors except one, which one?
Temperature
Water
Carbon dioxide
Chlorophyll
Which of the following is a micronutrient?
Manganese
Zinc
Phosphorus
Copper
The storage organ for carrot is,
Bulb
Tap root
Stem tuber
Corm
Matching items questions.
LIST A
LIST B
Mineral required in small quantities
Broad part of a leaf that contains photosynthetic tissues
A term used to describe both xylems and phloem
Responsible for opening and closing of stomata
Light stage of photosynthesis takes place here.
Break down of water into hydrogen ions and oxygen
Carbon dioxide combines with oxygen
Chemical form in which energy is stored
The storage organ of cocoyam
Transport of manufactured food from the plant leaves to other parts.
Vascular bundles
Translocation
Lamina
Petiole
Trace elements
Macroelements
Grana
Stroma
Guard cells
Palisade cells
ATP
ADP
Bulbs
Root tuber
Corms
Hydrolysis
Photolysis
Carbon dioxide fixation


SECTION B.
3.A) define the following terms
Photosynthesis
Photolysis
Carbondioxide fixation
b) Mention the raw materials for the process of photosynthesis
4. a) Write the overall equation for the process of photosynthesis
b) Differentiate between the light stage and dark stage of photosynthesis
c) Differentiate between macro-nutrient and micro-nutrients
5. a) Name the organ of the plant where the process of photosynthesis takes place.
b) Describe the structure and adaptations of the leaf to the process of photosynthesis
c) A part from the leaf, mention other parts where the process of photosynthesis can take place.
6. Briefly explain the roles of the following parts of the leaf
i) The cuticle
ii) Epidermis
Stomata
Mesophyll
7. a) What is the functions of the guard cell?
b) Give the adaptations of the guard cell to the process of photosynthesis
c) Briefly explain the mechanism of opening and closing of stomata
8. Describe in detail what happens during the light and dark stage of photosynthesis
9. a) Explain the importance of photosynthesis in nature
10. Discuss the main storage organs used by plants to store food after photosynthesis


Page 3


TOPIC : 5  BALANCE OF NATURE

BIOLOGY EXAMINATION FORM TWO
TOPICAL EXAMINATIONS.
BALANCE OF NATURE.


NAME………………………………………..CLASS………………………………………….……………TIME: 21/2HRS
INSTRUCTIONS:-
This paper consists of sections A, B and C
Answer all questions
All answers must be written in the spaces provided
All writings should be in blue/black inks except for drawings that should be in pencils


SECTION A. 20 MARKS.


Multiple choice questions.
In parasitism
both the parasite and the host benefit
both the parasite and the host lose
the parasite benefits while the host loses
the parasite loses while the host benefits.
Carbon dioxide is reduced in the atmosphere through
volcanic activities
burning of organic matter
respiration
photosynthesis.
iii) A vulture feeds on dead bodies of animals. The vulture is best described as
A. an omnivore B. a carnivore
C. a decomposer D. a scavenger.
iv) Which of the following is an example of a mutualistic relationship?
A caterpillar eating tomato plant.
A flowering plant and its pollinators.
A plasmodium inside the human body.
A tick and a cow.
v) When two organisms live together for their mutual benefit the relationship is called
commensalism
symbiosis
epiphytism
saprophytism.
vi) Which of the following apply in a balanced grassland ecosystem?
There are more consumers than producers.
Decomposers act on producers only.
Producers and consumers are usually in equal numbers.
Producers are more numerous than consumers.
vii) Which of the following groups of organisms is not a producer?
Planktonic algae.
Cyanobacteria.
Green plants.
Fungi.
viii) Light from the sun is never
absorbed by the consumers
reflected back
absorbed by the clouds
absorbed by the producers.
ix) Which of the following ecological statements about cattle and goats is most correct?
Cattle are more efficient in assimilation of food materials taken in as compared to goats.
They are both herbivores but goats are grazers while cattle are browsers.
Cattle are mainly grazers while goats are browsers.
The goats are monogastric while cattle are ruminant.
x) Green plants are known as producers because,
A. They make their food from simple substances
B. They produce green leaves
C. contain fruits and seeds
D. Produce green leaves.


Matching items questions.
LIST A
LIST B
Interconnected food chains
The living components of the environment
Organism that make organic food molecules from carbon dioxide water and inorganic raw materials
A series of organism through which energy is passed in form of food
All living and non living things that occur naturally on earth
Interaction that is beneficial to all organisms involved
Organism occupying the final trophic level
Interaction in which one organism captures, kills and feeds on another
Temperature, wind, light soil water atmospheric pressure and altitude
Converts nitrogen gas into nitrates.
Rhizobium
Azobacter
Biotic component
Predation
Commensalism
Food web
Producers
Neutralism
Water cycle
Food chain
Natural environment
Competition
Carbon cycle
Mutualism
Decomposers
Parasitism.


3. (a) Name two examples of leguminous plants.
(b) The swelling shown on the contain microorganisms.
Name these microorganism
What is the importance of these microorganism the plant?
What term is used to describe the relations between the plant and microorganisms?
4. (a) Give the name of:
The bacteria that cons nitrates into nitrites a ammonia.
A nitrifying bacterium that converts ammonia in nitrites.
A nitrifying bacterium converts nitrates into nitrites.
(b) State two ways through nitrogen is made available plant.
5. a) Briefly explain the following terms;
i) Trophic level
ii) Food chain
food web
b) With examples, briefly explain how the following interactions of living organisms takes place
i) Predation
ii) Parasitism
6. a) With examples state the meaning of abiotic and biotic factors of the environment
B) i) Differentiate the term food chain from trophic level
ii) Construct a food chain by using the organisms below, grass, bacteria, lion and zebra.
7. Briefly discuss the role played by each of the following in an ecosystem.
Green plants.
Bacteria and fungi.
8. An ecologist carried out a survey to estimate the number of organisms in a certain dam. The following table shows the record of the survey.
Organisms
Estimated
number
Microscopic algae
450,000
Small fish
290
Mosquito larvae
5,500
Crocodiles
10
Large fish
160


(a) Which of the above organisms are called the
Producers?
Primary consumers?
Consumers of the last order?
(b) Which organism is likely to get finished first in the dam? Give a reason to support your answer.
(c) Draw a possible food web that shows the energy flow in the dam.




Page 4


TOPIC : 6  TRANSPORT OF MATERIALS

BIOLOGY EXAMINATION FORM TWO
TOPICAL EXAMINATIONS.
TRANSPORT OF MATERIALS


NAME………………………………………..CLASS………………………………………….………..……TIME: 21/2HRS
INSTRUCTIONS:-
This paper consists of sections A, B and C
Answer all questions
All answers must be written in the spaces provided
All writings should be in blue/black inks except for drawings that should be in pencils
-
SECTION A.20 MARKS.


Multiple choice questions
The removal of a bark from the trunk of a tree kills the tree because the
supply of food to the roots is cut off
supply of carbon dioxide to the leaves is cut off
supply of water to the leaves is cut off
trunk loses the required strength and protection.
ii) An epidermal cell from a leaf was put in a hypertonic solution. After sometime the cell could be said to be
A. crenated B. turgid
C. flaccid D. deplasmolysed.
iii) Which of the following blood vesseles contains blood rich in dissolved food substances?
Hepatic portal vein
Aorta
Renal vein
Mensenteric artery


iv) The following blood vessels carry oxygenated blood except the
pulmonary vein
aorta
venacava
coronary artery.
v) A patient having blood group B can receive blood from a donor who belongs to
group B only
group 0 only
group B or group 0
group AB only
vi) Blood group AB is referred to as
antibody
antigen
universal donor
universal recipient.
vii) Which of the following sets present in mammalian blood is directly concerned with direct combating diseases?
Red blood cells.
Platelets and antibodies.
White blood cells and red blood
cells.
White blood cells and antibodies.
viii) Which of the following is not a function of the blood?
Secretion of hormones.
Natural healing of wounds.
Transport of gases to and from the tissues.
Regulation of body temperature.
ix) Three components of blood important in blood clotting are
leucocytes, thrombocytes and fibrinogen
thrombin, fibrinogen and thrombocytes
thromboplastin, thrombocytes and fibrinogen
erythrocytes, leucocytes and thrombocytes.
x) All of the following are suspended in the plasma except......................
A. Red blood cells
B. Platelets
C. Capillaries
D. White blood cells
2. Matching items questions.
LIST A
LIST B
Continous column of water from the roots to the leaves.
Loss of water from the stems in form of droplets.
Transport of food substances from leaves to other parts of plants.
Solution with equal concentration as surrounding regions.
The process that occurs when blood cell gain water and burst.
Prevents back flow of blood into left ventricle.
The clumbing together of blood
The hardening of arteries
Movement of fluid in vessels in large quantities
The difference in concentration of molecules between two regions.
Osmosis
Diffusion gradient
Semi-permeable membrane
Hypotonic solution
Isotonic solution
Mass flow
Active transport
Translocation
Transport
Guttation
Transpiration
Biscuspid valves
Tricuspid valves
Semi lunar valves
Thrombosis
Arteriocleriosis
Haemolysis
Crenation
Transpiration stream
Transpiration pull


3. Distinguish between the following terms:
Diffusion and osmosis.
Hypertonic solution and hypotonic solution.
Plasmolysis and haemolysis.
Turgor pressure and wall pressure.
Osmotic pressure and osmotic potential.
4. Define the following terms:
Mass flow
Isotonic solution
Deplasmolysis
Turgid
Flaccid
A) What are the factors affecting the rate of osmosis?
Explain the factors that affect the rate of active transport.
A) explain what would happen if;
Spleen and tonsils are removed from the body
Capillaries had thick walls
Left ventricles had thin walls
b) Give reasons why:
i) Small organisms such as amoeba do not need elaborate gaseous exchange system
ii) The left ventricle has a muscular thick wall than the right ventricle
iii) Blood in arteries flows in pulses
A) What is blood transfusion?
b) Explain the considerations to be taken before blood transfusion is carried out.
c) State two functions of mammalian blood other than transport of substances.


A) Define the following terms;
Capillarity
Transpiration pull
Root pressure
Transpiration stream
b) Differentiate between cohesion and adhesion forces.
9. Answer the following questions briefly;
i) Explain four environmental and plant factors that affect the rate of transpiration
ii) Mention and explain factors facilitate the water uptake of water in plants
10 (a) Differentiate between the following terms
Osmosis and diffusion
Hypotonic and hypertonic solution
Passive and active transport.
b) State the role of the following in photosynthesis.
i) water
ii) sunlight
Carbon dioxide
Page 4


TOPIC : 6  TRASPORT OF MATERIALS IN MAMMALS

P CLASS="western" ALIGN=CENTER STYLE="margin-bottom: 0.11in; line-height: 150%"> CHAPTER 6
TRANSPORT OF MATERIALS IN MAMMALS
KEY TERMS AND CONCEPTS.
Pericardium- this is a tough membrane which cover the heart
Pericardial fluid- this is a fluid which enables a membrane to move smoothly against each other.
Epicardium- this is the outer protective layer of the heart
Myocardium- this is the middle layer of the heart
Erythrocytes- this is another name for red blood cells. They are responsible for transport of oxygen.
Haemoglobin- this is a chemical substance that carries oxygen
Thromboplastin- a chemical substance that initiates the process of blood clotting
Agglutination- this is the clumbing together of blood when antigen A and antibody a comes into contact.
Erythroblastosis foetalisis- occurs when a rhesus positive mother give birth to a rhesus negative baby leading to destruction of foetus red blood cells. This can be fatal.
Compatible blood- this is blood which can be mixed without agglutination.
Universal receipient- this is an individual who can receive blood from any blood group, these individuals have blood group AB.
Universal donar- are individuals who can donate blood to any blood group. These individuals have blood group O.
Pulmonary circulation- this is the circulation of blood from the heart to the lungs and back to the heart.
Systemic circulation- this is circulation of blood from heart to the rest of the body parts and back to the heart.
Intestinal fluid- this is a fluid that is composed of water nutrients, oxygen hormones and bathes the cells.


Introduction
Transport in mammals is quite different from organisms because of their complex nature. Their bodies are made up of numerous cells and tissues. Thus, diffusion alone is not enough to ensure efficient carrying out of life processes. Mammals therefore have an elaborate transport system called the circulatory system. The circulatory system is made up of the heart, the blood and the blood vessels.
The mammalian heart
The heart is a muscular organ located in the chest cavity between the lungs.
An example of the mammalian heart is the human heart. The human heart is approximately the size of a clenched fist.
It is located in the chest cavity between the two lungs.
This position offers protection for the heart from injury
The external structure of the mammalian heart
The mammalian heart is broader at the top and narrower at the bottom.
It is enclosed by a double layer of tough inelastic membranes called the pericardium.
The membranes prevent the heart from over-expanding when it is beating very fast.
The pericardium also secretes a fluid called pericardial fluid. This fluid enables the membranes to move smoothly against each other.

Figure 6.1 External structure of the heart


The wall of the heart is made up of the cardiac muscles. Cardiac muscle is never fatigued. It works continuously as long as a person is alive. This type of muscle is found only in the heart.
The wall of the heart has three layers:
The epicardium is the outer protective layer.
The myocardium is the middle layer.
The endocardium is the innermost layer. This layer is continuous with the lining of the blood vessels attached to the heart.
The coronary artery supplies the heart with oxygenated blood. The coronary vein carries blood containing waste materials away from the heart.
The vena cava and pulmonary vein bring blood from the rest of the body to the heart.
The aorta and pulmonary artery transport blood from the heart to the rest of the body.
The internal structure of the mammalian heart


The heart has four chambers: right auricle, right ventricle, left auricle and left ventricle. The auricles are also called atria (singular: atrium).
The walls of the ventricles are thicker than those of the other parts of the body.
The left ventricle is thicker than the right ventricle because the right ventricle pumps blood to the lungs while the left ventricle pumps blood to the rest of the body.
The heart has several valves. Valves have flaps that ensure that blood flows in one direction only.
The tricuspid valve is found between the right auricle and right ventricle. The bicuspid valve is found between the left auricle and left ventricle.
Semilunar valves are located at the bases of the pulmonary artery and aorta to prevent blood from flowing back into the ventricles.

Figure 6.2 Internal structure of the heart.
Valves close when blood tries to flow back.
The left and right sides of the heart are separated by the septum. The septum is a thick muscular wall that prevents mixing of oxygenated and deoxygenated blood.


THE FLOW OF BLOODTHROUGH THE HEART
The process of blood flow through the heart is explained as follows;
The vena cava brings deoxygenated blood to the heart. Deoxygenated blood contains low amounts of oxygen.
The vena cava has two branches:
The superior vena cava which transports deoxygenated blood from the upper parts of the body such as head, neck and upper limbs.
The inferior vena cava which transports deoxygenated blood from the lower parts of the body such as the lower limbs, kidney, liver, stomach and intestines.
The inferior vena cava and the superior vena cava unite to form the vena cava. The vena cava is connected to the right auricle.
When the right auricle relaxes, it fills up with deoxygenated blood from the vena cava.
There is increased pressure in the right auricle when the muscles contract.
This pushes the blood through the tricuspid valve. The muscles of the right ventricle relax

Figure 6.3 blood circulation in the body.
and it fills up with blood.
The tricuspid valve closes to prevent blood from flowing back into the right auricle.
When the right ventricle is full, the increased pressure causes the muscles to contract and the semilunar valve in the pulmonary artery to open. The blood flows into the pulmonary artery and the bicuspid valve closes to prevent back flow of blood.
The pulmonary artery transports blood to the lungs. Blood absorbs more oxygen in the lungs, and thus becomes oxygenated.
Oxygenated blood flows to the heart through the pulmonary vein. This vein is connected to the left auricle.
When the left auricle relaxes, the semilunar valve opens and blood from the pulmonary vein flows in.
Pressure increases in the left auricle as it fills up with blood. The pressure causes the muscles of the auricle to contract and pump blood through the bicuspid valve into the left ventricle.
The muscles of the left ventricle contract, allowing blood to flow in. The bicuspid valve closes to prevent blood from flowing back into the left auricle.
Pressure builds up in the left ventricle as blood flows in.
The muscles of the left ventricle contract, pumping blood through the semilunar valve into the aorta.
The aorta branches into smaller arteries that transport blood to all parts of the body. The heart beats in such a way that when the auricles contract, the ventricles relax and vice versa.
In the right atrium, there is a small patch of muscle called the sinoatrial node (SAN). This node acts as a pacemaker, setting the time and rate of cardiac muscle contraction.
Adaptations of the heart to its function
Blood vessels
Mammals have three types of blood vessels: arteries, veins and capillaries.
Arteries
Arteries are thick-walled, muscular and elastic vessels that transport blood from the heart to all parts of the body.
All arteries transport oxygenated blood, except the pulmonary artery which transports deoxygenated blood from the heart to the lungs.

Figure 6.4 Artery
The endothelium is the innermost layer of the artery. It has only one layer of cells. The endothelium surrounds the lumen (the central tube of the vessel).
The lumen of an artery is narrow and smooth so that it can transport blood at high pressure.
The muscular layer is made of smooth muscle and elastic fibers. Smooth muscle is arranged in circles round the endothelium.
This layer makes it possible for the artery to contract and relax for the efficient movement of blood.
The outermost layer is the fibrous layer made of connective tissues such as collagen. The fibers are arranged parallel to the length of the vessel.
They enable the artery to withstand the pressure caused by the blood coming from the heart.
When the ventricles contract, the arteries relax allowing blood from the heart to flow into them.
When the ventricles relax, the arteries contract, forcing the blood forward. This contraction and relaxation of arteries is felt as a pulse.
Pulse rate is the number of pulses per minute. The pulse rate reflects the heartbeat. An adult humans heart beats at an average of 72 times a minute.
However, this can increase or decrease due to physical activity, emotional state or health factors.
The blood vessels.
The mammals have three types of blood vessels. These are arteries, veins and capillaries.
Arteries.
They arise from the heart and carry blood away from it. The biggest artery is the aorta which branch into arterioles and supplies blood into body tissues. The arterioles branch further into veins.
Features of arteries
All carry oxygenated blood except pulmonary artery
They have thick muscular wall
They carry blood away from the heart
Blood flow in very high pressure
They have small lumen
They do not have valves
They are deep rooted




Veins
Veins are vessels that transport blood to the heart from all parts of the body. All veins transport deoxygenated blood except the pulmonary vein the pulmonary vein transports oxygenated blow from the lungs to the heart.
Properties of veins.
They carry deoxygenated blood except blood except the pulmonary vein.
Have thin and less muscular walls
Carry blood towards the heart
Blood flow in low pressure
They have wide lumen
Blood flow smoothly
They have valves at intervals
Figure 6.6 veins
Factors that facilitate movement of substances in veins
The muscles next to the veins squeeze the veins and help to force blood to flow towards the heart. The contraction of the ribs during breathing also helps to squeeze some veins and keep blood flowing.
Capillaries
Capillaries are the smallest blood vessels. They are narrow and have walls that are one cell thick.
Capillaries are in direct contact with the tissues of the body. They form a network for the efficient diffusion of substances. Their thin walls maximize the rate of diffusion.
The thin walls of the capillaries enable oxygen and nutrients to diffuse from the blood to the cells, carbon dioxide and other waste products to diffuse from the cells into the blood and white blood cells to reach sites of infection.

Figure 6.7 Capillaries
Capillaries join to form venules (small veins) which join to form veins.
Blood
Blood is a fluid tissue. It consists of cells red blood cells and white blood cells and platelets suspended in a fluid called plasma. An adult human has 4 to 6 liters of blood. The pH of blood is 7.4.
Plasma
Plasma is a pale-yellow fluid. Approximately 55% of the blood is plasma.
Plasma is mostly made up of water but it also has dissolved substances such as food nutrients, metabolic wastes, oxygen, proteins and mineral ions.
These solutes make up 8% of the plasma while water makes up 92%.
The major functions of plasma are the transportation of:
nutrients from the digestive system to the whole body
red blood cells containing oxygen to the tissues
wastes such as carbon dioxide and urea to the excretory organs
white blood cells and antibodies to sites of infection
hormones to the target organs
mineral ions such as sodium, potassium and chlorides
Platelets to sites of bleeding.
Plasma is also important for distributing heat to all parts of the body, regulating the pH of body fluids and it is where the exchange of nutrients and waste products takes place in the body.
Red blood cells
Another name for the red blood cells is erythrocytes. They are red, round biconcave cells with no nucleus. One milliliter of blood has approximately 5 to 6 million red blood cells.
Figure 6.8 Red Blood Cells
Red blood cells are formed in the bone marrow their lifespan is about 120 days.
The liver and the spleen destroy old red blood cells and release hemoglobin for the formation of new cells.
Hemoglobin is the red pigment in erythrocytes. It has a high affinity for oxygen.
The function of red blood cells is to transport oxygen and carbon dioxide.
The adaptations of red blood cells.
The presence of haemoglobin,
Their large numbers,
Are biconcave shape and
They lack of a nucleus which increases the total surface area for gaseous exchange.
Transport of oxygen
In the lungs (where there is a high concentration of oxygen), hemoglobin combines with oxygen to form oxyhaemoglobin.
This is an unstable compound which releases oxygen when it reaches tissues that have a low concentration of oxygen.
The formation of oxyhaemoglobin and release of oxygen and haemoglobin can be shown using the following equation.
haemoglobin + oxygen oxyhaemoglobin
Oxygen diffuses out of the red blood cells, through the capillary walls to the tissues.
Transport of carbon dioxide
In the red blood cells, carbon dioxide combines with haemoglobin to form carbaminohaemoglobin. This compound is transported to the lungs where carbon dioxide is released and expelled from the body.
White blood cells
Another name for the white blood cells is leucocytes. These cells have irregular shapes.
One millilitre of blood has approximately 5 000 to 10 000 white blood cells.
White blood cells are produced in the bone marrow and in the lymph nodes.
Figure 6.8 Leucocytes.
The function of white blood cells is to protect the body against infection. They perform this function by:
Engulfing and destroying pathogens
Producing substances that neutralize toxins produced by pathogens.
Causing clumping together of foreign materials in the body.
Killing infected body cells.
Preventing clotting in damaged tissues.
The effect of HIV on white blood cells
The HIV attacks a type of white blood cells called helper-T cells.
These cells are essential for body immunity.
When they encounter an antigen, the helper-T cells divide themselves to form new cells.
This increases the number of cells available to fight the infection.
After the infection, some cells remain as memory cells to activate an immune response if the infection happens again.
In addition helper-T cells activate other cells in the immune system.
HIV has a protein envelope that can only bind to its receptor called CD4 found on the cell membrane of the helper-T cell.
When it enters the human body, HIV fuses its protein envelope with the CD4 then enters the cell.
Once inside the cell, the virus becomes part of the helper-T cell and replicates together with it as it undergoes division.
This increases the amount of HIV in the blood. The HIV destroys helper-T cells resulting in the reduction of the number of helper-T cells and reducing the CD4 count.


Platelets
Platelets are also called thrombocytes. They are fragments of cells produced in the bone marrow. One milliliter of blood contains about 250 000 to 400 000 platelets.
They play an important role in the clotting process.
The clotting process
Platelets at the site of an injury produce thromboplastin which starts off the clotting process.
Thromboplastin, with the help of vitamin K and calcium neutralizes heparin, an anticoagulant in blood.
Heparin converts prothrombin (which is an inactive plasma protein) to thrombin (an active plasma protein).
Thrombin catalyzes the conversion of soluble fibrinogen to insoluble fibrin. Fibrin forms a network of fibres that traps debris and blood cells. The result is a clot at the site of the wound preventing further loss of blood.
Blood groups and blood transfusion
Grouping of human blood is done using the ABO system and the Rhesus factor.
The ABO system
The ABO system of grouping blood depends on two things. First is the presence or absence of antigen A or antigen B on the membranes of the red blood cells. Second is the presence of antibody a or antibody b in the blood plasma.
Table 6.1
A person cannot have a certain antigen on the membrane of the red blood cell and also have the corresponding antibody in the plasma.
For example, you cannot have both antigen A and antibody a. This would cause agglutination or clumping together of red blood cells. Agglutination can be fatal.
The various blood groups and the antigens and antibodies present in them are summarized below.
Rhesus factor
This factor is named after the Rhesus monkey in which it was first observed.
When the rhesus factor is present on the red blood cell membrane, a person is said to be rhesus positive. This is abbreviated as Rh+.
If it is absent, the person is rhesus negative. This is abbreviated as Rh-.
Thus, a persons blood is said to be A+ if it is blood group A and has the rhesus factor, or A- if it is blood group A but lacks the rhesus factor. There are also B+ or B-, 0 or 0- and AB+ or AB- blood groups.
If a rhesus negative woman marries a rhesus positive man, their children are highly likely to be rhesus positive.
During the last months of pregnancy, the rhesus antigen from the foetus passes into the mothers blood.
This causes the mothers body to produce antibodies which destroy some of the foetuss red blood cells.
This destruction is minimal in the first child but in the children that follow, a lot of destruction could take place, killing the foetus.
This is called haemolytic disease of the newborn or erythroblastosis foetalis. To prevent this, the mother is treated with anti-rhesus globulin. This prevents her body from forming antibodies against the rhesus antigen.
Blood transfusion
Blood transfusion is the transfer of blood from one person (the donor) to another (the recipient).
It is necessary to replace blood when the recipient has a blood disorder or has lost a lot of blood due to surgery or an accident.
In order for blood transfusion to be successful, the blood of the donor and that of the recipient must mix without agglutination.
When this happens, the blood is said to be compatible. If the blood is incompatible, agglutination occurs.
Table 6.2
Blood compatibility depends on the blood groups of the donor and the recipient. For example, if a person of blood group A receives blood from a person of blood group B, the recipients body produces antibodies against antigen B. This is because the antigen is seen as foreign material.
Individuals with blood group AB are called universal recipients. They can receive blood from people of any blood group. However, they can only donate blood to someone with blood group AB.
Those with blood group 0 are universal donors. They can donate blood to people of all blood groups. On the other hand, they can only receive blood from someone with blood group 0.
The following is a compatibility table for the different blood groups.
If blood from a rhesus positive person is transfused to a rhesus negative person, the recipient produces rhesus antibodies.
If such a transfusion is done a second time, massive agglutination can occur. This can lead to loss of life.
Precautions taken during transfusion
Blood from the donor must be checked for compatibility with blood from the recipient in terms of both ABO blood group and rhesus factor in order to avoid agglutination.
The donors blood must be screened to ensure that it does not have pathogens that can cause diseases such as HIV and AIDS, syphilis and hepatitis B.
Donated blood is stored in special bags and an anticoagulant is added to prevent it from coagulating.
Donated blood is kept in a refrigerator for a maximum of 21 days. After that it expires and should not be used.
Advantages of blood transfusion
It ensures rapid replacement of blood lost from the body, for example during surgery or due to an accident.
Blood transfusion is used to treat diseases such as sickle-cell anaemia.
Disadvantages of blood transfusion
There are no exact blood matches. Blood is a complex tissue that contains many different things. One persons blood cannot be exactly the same as anothers. Hence, there are chances of developing a reaction to transfused blood.
Transfused blood may not always be free of infections.
Blood circulation in human beings
Blood circulation is the movement of blood from the heart to all parts of the body and back to the heart.
Human beings exhibit double circulation where by the blood passes through the heart twice for each complete circulation.
In other less complex organisms like the fish, blood goes through the heart only once; this is known as single circulation.
Figure 6.9 Systemic circulation.
Pulmonary circulation
During pulmonary circulation, deoxygenated blood is brought to the heart through the vena cava.
This blood is emptied into the right auricle.
The right auricle pumps blood to the right ventricle.
When the right ventricle contracts, it pumps blood to the lungs through the pulmonary artery.
In the lungs, the blood is oxygenated.
It then flows back to the heart through the pulmonary vein.
The movement of blood between the heart and the lungs is called the pulmonary cycle.
Systemic circulation
In systemic circulation, the pulmonary vein transports blood to the left auricle.
The left auricle then pumps the blood into the left ventricle.
The left ventricle has strong muscles that pump blood to all parts of the body.
After the tissues have derived their requirements from the blood, it flows back to the heart through the vena cava.
This movement of blood between the heart and the various parts of the body is called the systemic cycle.


Formation of tissue fluid
The aorta is the largest artery in the body.
It branches into smaller arteries, which in turn branch into even smaller vessels called arterioles.
Arterioles branch into capillaries which are in contact with the tissue of the body.
The capillaries have tiny pores that allow some components of blood to filter into the tissues.
At the arterial end of the capillary, there is high blood pressure. This forces fluid out through the tiny pores in the capillaries.
The fluid is composed of water, oxygen, hormones and nutrients. This fluid bathes the cells. It is called tissue fluid or interstitial fluid.
 Figure 6.10 Capillary end.
The substances in this fluid diffuse into the cells through the cell membrane. In addition, the waste products from the cells diffuse into the tissue fluid. These wastes include carbon dioxide, minerals, heat and nitrogenous wastes.
At the venous end of the capillary, blood pressure is low; water potential is also low. The pressure of the tissue fluid is higher.
This forces the tissue fluid back into the capillaries. Diffusion also helps in the re-entry of tissue fluid to the capillary.
However, some tissue fluid remains within the cells. This later enters the lymphatic system to form lymph.
The capillaries join to form venules. Venules join to form veins. The veins transport blood back to the heart.
Veins in the lower part of the body unite to form the inferior vena cava while veins in the upper part of the body unite to form the superior vena cava.
These two large veins join to form the vena cava which transports blood to the right auricle of the heart.
Importance of blood circulation
It enables the transportation of cell requirements such as oxygen and nutrients to all the body tissues.
It ensures that waste products from the cells are removed in order to prevent accumulation. Accumulation of waste products is harmful to the body.
Blood circulation is important for the regulation of body temperature. Body heat is transported to all parts of the body through this system. Blood circulation also transports hormones from the organs that produce them to the organs where they are needed.
Blood pressure
Blood pressure is measured by considering the systolic pressure and the diastolic pressure.
Systole occurs when the ventricles contract and pump blood into the arteries.
Diastole is the phase when the auricles contract to pump blood into the ventricles.
The pressure developed during these actions can be felt in the arteries. It is measured in millimetres of mercury (mmHg).
The pressure during systole is 120 mmHg and the pressure during diastole is 80 mmHg, the blood pressure is 120/80 mmHg.
This is the average blood pressure in a normal human being. A sphygmomanometer is the instrument used to measure blood pressure.
Diseases and disorders of the human circulatory system
Eating food with high levels of cholesterol and fat causes narrowing of blood vessels due to deposition in blood vessels .
The diseases and disorders of the human circulatory system are increased by eating habits and lifestyles.
Smoking, lack of exercise, stress and taking alcohol also put one in danger of developing heart problems such as coronary heart disease and high blood pressure.
Arteriosclerosis
Arteriosclerosis is the hardening of arteries. It happens when there are fat deposits on the wall of the artery or when fibrous tissues form in the artery wall or artery walls degenerate.
Arteriosclerosis hinders the arteries from pulsating normally. The lumen is narrowed, affecting the As a result, the heart has to pump harder in order to supply the tissues with enough blood.
The result of this is high blood pressure (hypertension). High blood pressure usually has no specific symptoms. However, it can cause headaches, dizziness and ringing in the ears.
Causes of arteriosclerosis
Arteriosclerosis is mainly caused by excessive alcohol and smoking, stress, too much fat in the diet, lack of exercise or old age.
Effects of arteriosclerosis
Arteriosclerosis causes swelling of part of a blood vessel and rupturing of the artery walls.
It also causes total blockage of an artery, thus depriving some tissues of oxygen.
This can cause the affected tissue to become severely damaged or to die.


Prevention and treatment of arteriosclerosis
People can prevent themselves from arteriosclerosis by avoiding alcohol and smoking, reducing stress, minimizing intake of fatty foods and engaging in regular exercise. Arteriosclerosis can be treated by medication or surgery.
Sickle-cell anemia
This condition is a genetic disorder which causes production of abnormal hemoglobin and malformed red blood cells.
The effect is a reduction of the bloods capacity to transport oxygen. The disease gets its name from the crescent or sickle shape of the red blood cells.
Signs and symptoms of sickle-cell anaemia
Sickle-cell anemia is characterized by fatigue or excessive tiredness, shortness of breathe exercise, headeaches, dark-coloured urine, abdominal pain, abnormal heartbeat and general body weakness.
Treatment and prevention of sickle-cell anemia
Sickle-cell anaemia has no cure. It is difficult to prevent since it is inherited. However, patients can be helped by making sure that they avoid excessive physical exercise and eat a well-balanced diet that is rich in minerals and vitamins.
Leukaemia
Leukaemia is a type of blood cancer. It is caused by the over production of white blood cells and the suppressed production of red blood cells.
The excess white blood cells infiltrate body organs, for example the liver and the spleen. This causes reduced efficiency in the functioning of these organs and their abnormal enlargement.
Signs and symptoms of leukaemia
Leukemia is characterized by abnormally high numbers of white blood cells, abnormal bleeding, e.g. nose bleeding, bleeding even from minor cuts, extreme body weakness, anaemia, and throat and mouth infections that may be recurrent.
Treatment of leukaemia
Leukaemia cannot be cured. However, it is controlled by frequent blood transfusions, radiotherapy and chemotherapy to kill the abnormal cells, and bone marrow transplants.
High blood pressure (Hypertension)
The blood pressure of a normal human being is 120/80 mmHg. Very high blood pressure (over 170/90 strains the blood vessels and causes hypertension and sometimes heart failure.
Increase in blood pressure may be caused by high fat levels due to over-consumption of fatty foods, lack of exercise, obesity, high emotional stress, alcoholism and smoking, and arteriosclerosis.
Signs and symptoms of hypertension
The signs and symptoms of hypertension include feeling dizzy, ringing sound in the ear and severe headaches.


Prevention and treatment of hypertension
Hypertension can be prevented by engaging in regular exercises, avoiding alcohol and smoking, eating a balanced diet with less fat to control weight and reducing stress as much as possible. Hypertension can be treated using drugs.
Coronary thrombosis
Coronary thrombosis occurs when there are blood clots in the blood vessels that supply blood to the heart (coronary arteries).
This prevents blood from reaching some tissues of the heart. The affected tissues lack adequate amounts of oxygen and waste materials accumulate in the cells to toxic levels.
Symptoms of coronary thrombosis
Coronary thrombosis is characterized by uncomfortable pressure or sharp pain in the chest, sometimes extending to the neck, shoulders and arms, excessive sweating, dizziness or fainting, nausea or a feeling of severe indigestion and shortness of breath.
Effects of coronary thrombosis
Coronary thrombosis can cause death of some cardiac tissue or sudden death.
Prevention and treatment of coronary thrombosis
People can avoid coronary thrombosis by doing regular exercise, avoiding sudden strenuous activity, avoiding alcohol and smoking, minimizing intake of fatty foods and avoiding excessive stress. Thrombosis can be treated by drugs.
Stroke
A stroke occurs when there is interference in the amount of blood flowing to the brain.
Such interference can be due to blockage or rupture of an artery supplying blood to the brain. This causes some brain cells to lack adequate oxygen and nutrients.
Symptoms of stroke
Symptoms of a stroke include sudden numbness or weakness especially on one side of the body sudden confusion or trouble in understanding or speaking and sudden poor vision in one or both eyes.
The patient also experiences sudden dizziness, loss of balance, trouble when walking or lack of coordination, and sudden severe headaches.
Effects of a stroke
A stroke has severe effects on the victim such as weakness or paralysis on one side of the body, leading to difficulties in movement and coordination.
It also causes lack of feeling on one side of the body, speech or language problems and loss of memory.
Other effects are behavior changes, difficulty when swallowing exhaustion.
Prevention and treatment of a stroke
A stroke can be avoided by avoiding drinking a smoking, ensuring your blood pressure remains Medication can help in the treatment of a stroke
The lymphatic system
The lymphatic system closely resembles blood circulatory system. It consists of lymph. Vessels through which lymph travels.
After cells get their requirements from tissue fluid, not all the fluid flows back into the capillaries. Part of it flows into lymph vessels.
Once in these vessels, the fluid is called lymph. Lymph is a pale-yellow fluid. It has the same components as tissue fluid, but more fatty substances.
Figure 6.11 Lymphatic system.
Lymph vessels unite to form larger vessels called lymph ducts.
There are two main lymphatic ducts; the right lymphatic duct empties into the right subclavian vein while the left lymphatic duct drains into the left subclavian vein.
The two veins join to form the superior vena cava. In this way, the contents of lymph enter the blood circulation system.
Lymphatic ducts form nodule-like structures called lymph nodes. These nodes are found in the abdomen, groin, armpits and neck.
Lymph nodes are important sites for the production of white blood cells. They also filter out foreign materials such as bacteria and dead tissue before they enter the bloodstream.
The flow of lymph depends greatly on the squeezing of lymph vessels by breathing movements, intestinal movements and muscular movements. The lymph vessels have valves to prevent back flow of lymph.
Importance of the lymphatic system
Lymph nodes produce lymphocytes (white blood cells) which help the body to fight diseases.
Lacteals enable absorption of fatty acids after digestion.
It provides a way of getting tissue fluid back to the circulatory system.
The spleen destroys worn out red blood cells.
The spleen, the adenoids and the tonsils produce antibodies which help in fighting
TOPIC : 7  RESPIRATION

BIOLOGY EXAMINATION FORM TWO
TOPICAL EXAMINATIONS.
GASEOUS EXCHANGE AND RESPIRATIONS.


NAME………………………………………..CLASS………………………………………….………..……TIME: 21/2HRS
INSTRUCTIONS:-
This paper consists of sections A, B and C
Answer all questions
All answers must be written in the spaces provided
All writings should be in blue/black inks except for drawings that should be in pencils
SECTION A.


MULTIPLE CHOICE QUESTIONS.
i) Oxygen passing from the atmosphere into the blood of a mammal takes one of the following routes. Which one?
A. Trachea - bronchi – bronchioles-alveoli
B. Trachea - bronchioles – bronchi-Alveoli
C. Bronchi - bronchioles – trachea-Alveooli
D. Bronchioles - bronchi – trachea-Alveoli


ii) Which of the following sets contains respiratory gases only?
A, Oxygen and argon
Oxygen and carbon dioxide
Hydrogen and argon
Carbon dioxide and hydrogen
iii) Where does gaseous exchange take place in man?
A. Gills B. Trachea
C. Lungs D. Skin
iv) The lungs are enclosed in double membrane known as
plasma lemma
plasma membrane
lung membrane
pleural membrane.


v) The following are characteristics of a respiratory surface, which one is not?
Has a large surface area.
Has a good network of blood capillaries.
Has thick membrane.
Has moist surface.
vi) Where does gaseous exchange take place in a plant?
Spongy mesophyll cells.
Palisade cells.
Guard cells.
Stomata.
vii) Which of the following statements is not true?
A. During the day plants take in carbon dioxide.
During the day plants take in oxygen.
At night plants take in oxygen
At night plants release carbon dioxide.
viii) Terrestrial plants obtain respiratory gases from
the surrounding water
the atmosphere
A and B
none of the above.
ix) The compound in which oxygen is transported is referred to as
oxyhaemoglobin
carboxyhaemoglobin
haemoglobin
haemorrhage.
x) One of the following is not a respiratory surface
A. skin B. nostrils
C. gills D. mouth cavity.
2. Matching items question.


List A
LIST B
Gaseous exchange structure of amoeba.
Gaseous exchange structure of spider
Diffusion of gases in and outside the respiratory surface.
Found in chest cavity and filled with fluid which reduces friction
The form in which oxygen is carried in blood.
Areas with loosely packed cells which allows for gaseous exchange.
The inner membrane of a mitochondrion
The product of anaerobic respiration in animals
The least energy required by the body at rest.
A type of respiration which occurs in the cytoplasm.
Mitochondrion
Cristae
Pleural cavity
Pleural membrane
Cytoplasm
Cell membrane
Spiracles
Book lung
Respiratory quotient
Basal metabolic rate
Lenticels
Cork cells
Matrix
Anaerobic respiration
Lactic acid
Ethanol
Oxyhaemoglobin
carboxyhaemoglobin


SECTION B.


3. (a) Name the structures used for gaseous exchange in the following organisms:
Fish
Mammal
Bird
Grasshopper
Land ( terrestrial) green plants
Spider
Tadpole
Frog
Amoeba
Explain why it is not possible to drown or suffocate a locust or grasshopper by holding its head under water while the remaining part of the body is outside the water.
(a) Explain why a fish suffocates on dry land although atmospheric air contains more oxygen than water.
Give reasons why it is healthier to breathe through the nose than through the mouth.
(a) State the composition of inspired air and expired air in man.
(b) What is the role of the diaphragm during inspiration and expiration.
6. Explain why
It is not healthy to sleep in a closed room with potted plants
It is dangerous to sleep in a poorly ventilated room with a charcoal burner on
One pants during heavy exercises.
7. Explain why;
i) The rate of breathing increases rapidly during exercise
ii) Your breathing rate does not go back to normal as soon as you stop exercising.
8. i) (a) Why is it better to breathe through the nose and not the mouth?
b) Explain what will happen if epiglottis is removed from the body
ii) Briefly explain how breathing takes place in humans.
9. Differentiate between glycolysis and krebs cycle
10. Briefly give the differences between respiration and photosynthesis


Page 4


TOPIC : 7  TRANSPORT IN PLANTS

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CHAPTER 7
TRANSPORT IN PLANTS
KEY TERMS AND CONCEPTS.
Vascular bundles- these includes xylem and phloem which are responsible for conduction of water and food.
Cambium- this is a layer found between xylem and phloem and is responsible for secondary growth.
Lign- a substance found in xylem and helps in strengthening it.
Tracheid elements- are elongated cells with tapering ends for water conduction.
Sieve plates- They have perforations or pores
Companion cells- have high concentration of mitochondrion which provides energy for active transport.
Translocation- this is the movement of food substance within plant body.
Transpiration- this is the loss of water in form of water vapour from the plants
Transpiration stream- this is continuous movement of water from roots to the leaves as a result of transpiration pull.
Transpiration pull- this is a hidden force which pushes water up the plant from roots.
Cohesion force- this is the force of attraction between like molecules
Adhesion force- this is the force of attraction between different molecules


The transport system in plants is not as complex as that of animals. Materials are transported by vascular bundles made up of xylem and phloem tissues. Xylem tissue transports water and mineral salts from the soil to all parts of the plant. Phloem tissue transports manufactured food from the sites of photosynthesis to all parts of the plant. In between the xylem and phloem is cambium. The cambium divides to form new xylem and phloem.
Xylem
Xylem tissue is made up of the xylem vessels and the tracheids.
Mature xylem vessels and tracheids are made up of hollow and dead cells.
Their walls are made of cellulose and lignin. Lignin strengthens the cell walls and makes them rigid.
Therefore, xylem has an additional function of giving support to the plant.
The movement of substances in the xylem is always upward and is by conduction.
A xylem vessel is made of hollow cells without end walls. These cells are joined end to end to form a pipe-like structure.
Xylem vessels begin in the roots, go up through the stem and branch into every leaf of the plant.
Xylem vessels have no cytoplasm and nuclei. This enables them to transport a larger volume of water and mineral salts.
Tracheid elements are elongated with pointed (tapering) ends.
They are also laid end to end to enable continuous flow of water.
Their end walls have perforations (pits) unlike in xylem where end walls are missing.
This makes them less efficient in conduction of water.
Phloem
The phloem tissue is made up of sieve-tube elements and companion cells.
Like xylem vessels, sieve-tube elements are made of cells that are joined end to end.
However, the end walls of these cells are not completely broken down.
They have perforations or pores that form sieve plates. These cells contain cytoplasm but they have no nucleus. Fibres run through the pores thereby connecting adjacent sieve-tube cells.
Each sieve-tube element has a companion cell. They are separated by a thin wall made up of parenchyma cells with pores called plasmodesmata which allow exchange of materials between them.

Figure 7.1 Vascular Bundles
Companion cells have a high concentration of mitochondria. They provide the sieve-tube elements with energy.
The movement of substances in the phloem is by translocation. It can be in any direction.
The distribution of vascular bundles in plants.
The way the vascular bundles are arranged in the roots, stems and leaves of monocots and dicots differ. This arrangement also differs in the roots and stems of the two categories of plants.
Monocotyledonous root
The arrangement of vascular bundles is as shown




Dicotyledonous root
The xylem is centrally positioned and star-shaped. The phloem is found between the extensions of the xylem as shown below
Figure 7.2 vascular bundles in dicot and monocot roots
Monocotyledon stem
The arrangement of vascular bundles is random.
Figure 7.3 vascular bundles in dicot and monocot stems
Absorption and movement of water and mineral salts
Plants absorb water and mineral salts from the soil through root hairs.


Structure and functions of root hairs
Root hairs are extensions of the epidermal cells of the root.
Root hairs are long and slender to provide a large surface area for the absorption of water and mineral salts from the soil.
The large number of root hairs also increases the total surface area of the roots.
Transpiration occurs when water evaporates from the plant through the stomata in the leaves.
As the water is lost, the mesophyll cells draw water from the xylem in the leaf which in turn draws water from the xylem in the stem.
This creates a tension called transpirational pull which draws water from the roots.
This results in a continuous column of water from the roots, through the xylem to the leaves. This column of water is called transpirational stream.
Figure 7.4 Transpiration stream.


The root hair cell sap is usually hypertonic to the surrounding. Hence, water enters the cell by osmosis.
Root hair cells have a higher concentration of minerals than the surrounding. Mineral salts are therefore absorbed by active transport.
The root hairs are very thin in order to provide a short distance over which absorption of water and mineral salts takes place.
Movement of water and dissolved mineral salts
When water is absorbed by the root hair, it dilutes the contents of the cell sap vacuole.
As a result, the cells of the cortex, which are adjacent to the epidermis, have less water than the root hair cells.
Water moves from the root hair cells to the cortex cells by osmosis. It moves the same way into the cells of the endodermis, then into the pericycle and then into the xylem.


Capillarity
Capillarity is the action that causes water to rise in narrow tubes. Xylem vessels have a narrow lumen which makes it possible for water to rise in the by capillarity.
Capillarity is made possible by cohesion and adhesion forces. Cohesion is the attraction between like molecules.
It makes the water molecules stick to each other. Adhesion is attraction different molecules. It causes water molecules adhere to the xylem vessels.
Figure 7.5 Capillarity.
Root pressure
Root pressure pushes water and dissolved mineral salts upwards from the root.
This happens because the cells of the endodermis push mineral salts into the xylem.
This increases osmotic pressure in the xylem thereby creating a force that moves the water and dissolved minerals up the xylem vessel.
When a plant is cut, fluid oozes out of the remaining stem (stump). This is proof of root pressure in plants.
Figure 7.6 Root pressure.


Transpiration is the process by which plants lose water through the stomata in the leaves.
Water flows from the roots to the leaves through the xylem vessels. It enters the spongy mesophyll by osmosis.
The spongy mesophyll has substomatal air spaces where water enters as water vapour.
As a result, the concentration of water vapour in the substomatal air spaces becomes higher than the concentration of water vapour in the air. This causes water to diffuse into the atmosphere through the stomata.
Another process known as guttation also occurs in plants. It is the process by which plants lose water as droplets through special glands found where veins are in contact with the leaf margin.
Guttation is different from transpiration in that transpiration is the loss of water vapour mainly through the plants stomata. Guttation occurs mostly at night or in plants growing in wet areas.
Figure 7.7 Gutation
Types of transpiration
There are three types of transpiration:
Stomatal- This transpiration occurs through the stomata on the leaves. It accounts for approximately 90% of the water lost by plants.
Cuticular- A type of transpiration that happens through the cuticle of leaves. The cuticle is a waxy layer that covers the surface of leaves. A thick cuticle prevents excessive loss of water.
Lenticular transpiration takes place through the lenticels. Lenticels are pores found on the bark of stems or roots in woody plants.
Factors affecting the rate of transpiration.
The rate of transpiration is affected by plant features as well as environmental factors.
Plant features
Plant features include the following:
The size of leaves: A large leaf has more stomata than a small leaf. Therefore, plants with large leaves lose more water than those with smaller leaves.


An extensive root system: Plants that have extensive roots absorb more water and can therefore lose more water than those with few roots.
Leaf cuticle: A thick cuticle resists water loss by transpiration while a thin cuticle makes water loss by transpiration easier.
Number of stomata: The more stomata a leaf have, the faster the rate of transpiration and vice versa.
Position of stomata: Stomata on the upper surface of the leaf lose water more easily than those on the lower surface. If a plant has leaves with more stomata on the upper surface, the rate of transpiration is faster than in a plant that has leaves with more stomata on the lower leaf surface.
Size of substomatal air spaces: Larger air spaces allow for a faster rate of transpiration because the leaves can hold more water vapor. Smaller substomatal air spaces slow down the rate of transpiration.
Sunken stomata: Sunken stomata occur in pits. They are not exposed to moving air so they slow down transpiration rate.
Epidermal hairs: Epidermal hairs trap water on the surface of the leaves, thus preventing water loss.
Environmental factors
Temperature: Transpiration rates go up as the temperature goes up. Higher temperatures cause the stomata to open and release water into the atmosphere. Lower temperatures cause the stomata to close.
Relative humidity: As the relative humidity of the surrounding air rises, the transpiration rate falls. It is easier for water to evaporate into dry air than into air saturated with moisture.
Wind and air movement: Increased movement of the air around a plant results in a higher transpiration rate. As water transpires from a leaf, the water saturates the air surrounding the leaf. If there is no wind, the air does not move, thus raising the humidity of the air around the leaf. Wind moves the air causing diffusion gradient the more saturated air close to the leaf to be replaced by drier air.
Availability of soil moisture: When moisture is lacking in the soil, plants begin to senesce (age prematurely) resulting in leaf loss and reduced transpiration. Also, less water is absorbed by the roots when the soil is dry.
Light: Increased sunlight increases the rate of photosynthesis in the guard cells, causing them to become turgid and open the stomata. Higher light intensity also increases the plants internal temperature and hence increases the rate of transpiration.
Atmospheric pressure: When atmospheric pressure is low, for example at high altitudes, plants lose water more easily. The rate of transpiration is reduced in areas with high atmospheric pressure.
Significance of transpiration
It helps to maintain transpiration pull which is important for maintaining a constant stream of water between the roots and the leaves.
Transpiration enables the loss of excess water from the plant.
It helps to cool the plant and enables absorption and distribution of water and mineral salts.
SUMMARY.
The vascular system in plants is made up of xylem and phloem tissues.
Xylem transports water and minerals salts from the roots to all parts of the plant.
Phloem transports manufactured food from the site of photosynthesis to all parts of the plant.
The distribution of vascular bundles is different in roots and stems and in dicotyledonous and monocotyledonous plant.
Root hair are extensions of the epidermal cells of the root. They absorb water and minerals salts from the soil.
Water is absorbed from the soil by osmsosis.
Minerals salts are absorbed from the soil by active transport.
Water and dissolved minerals move up the xylem by transpiration pull, capillary and root pressure .
Transpiration is the process by which plants lose excess water through their leaves.
Transpiration is important because it:
Helps to maintain the transpirational stream
Enables the loss of excess water
Enables absorption and distribution of water and minerals salts in a plant.
Helps to cool the plant.
Transpiration is affected by the features of the plant and environmental factors. The features of the plant include: leaf size, size of root system, size of the leaf cuticle, Size of air spaces, number and position of stomata and whether the stomata are sunken or not, and the presence of epidermal hairs.
Environmental factors include the amounts of moisture in the air, temperature, air movement, availability of soil moisture, light and atmospheric pressure.


TRANSPORT OF MATERIALS IN PLANTS QUESTIONS
1. Choose the correct answer from the alternatives given.
Water and mineral salts in plants are transported through__________
Xylem
Phloem
Cambium
Epidermis
Which of the following forces does not facilitate upward movement of water?
Capillarity
Root of pressure
Mass flow
Transpiration
Before transpiration through stomata in leaves water vapour os stored in the ____________
Cuticle
Guard cells
Spongy mesophyll
Guard cells
Spongy mesophll
When the environment is too cold, plants lose water through________
Hydathodes
Cuticle
Stomata
Guard cell
Which the following decrease the rate of transport?
Numerous stomata
High wind
High temperature
High humidity
2. Write True for the correct statements and False for the wrong statement.
The other name of the transport system in plants is known as vascular system.
Xylem is made up of xylem vessels and sieve tubes.
Movement of substances through tracheas is more efficient than through xylem vessels.
Active transport goes against concentration gradient.
Minerals salts are less concentrated in the roof of a plant than in the soil.
3. (a) Differentiate between transpiration and guttation
__________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
(b) Explain why transpiration is the necessary evil? (3points in each case)
________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
4. Fill the blanks
__________ are elongated cells that have end walls performed by numerous minute holes in plants.
The end of walls of tracheids have holes called___________.
__________- is the force of attraction between similar molecules.
__________ is the force of attraction between different molecules.
The process which involves loss of water into the atmosphere through stomata in plants is known as________.
5. What do you understand by the following terms?
Transpiration
Root pressure
capillary
vascular system


6. What is the vascular system?
7. Briefly describe the components of the vascular system.
8. Explain the function of each component of the vascular system.
9. Write short notes on how water moves from the roots up to the leaves. Elaborate on the role of the forces involved.
10. without roots, no transportation. Explain this statement.
11. What is transpiration?
12. Explain why transportation has to take place in plants.
13. List down any four factors which affect the rate of transpiration in plants.


QUESTION AND ANSWER SECTION.
Q. i) Give the importance of transport in living organism.
Explain why amoeba does not need an elaborate transport system.
Define Diffusion, osmosis and mass flow.
iv)What factors affect rate of diffusion?
A. Transport is movement of material from one part of body of organism to another.
Importance.
Distribute food in body.
Help to eliminate waste products.
Assists in distribution of chemicals such as hormones.
Amoeba does not need an elaborate transport system because exchange of material occurs on its membrane, as it has a large surface area.
Osmosis is the movement of solvent molecule from region of high concentration to region of low concentration through a semi — permeable membrane.
Diffusion is movement of molecules from a region of high concentration to region of low concentration
Mass flow is movement of fluid in vessels; Within the body of organism.
i) Factors affecting diffusion rate include.
Diffusion gradient.
Size of molecules.
Thinness of membrane.
Temperature.
Q. Mention process in living organism that depends on diffusion.
A. These include.
Gaseous exchange
Absorption of food
Excretion of water.
Q. a) What do you understand by.
Hypertonic solution.
Hypotonic solution.
Isotonic solution.
b) In relation to above, explain what will happen when a plant cell and animal cells are placed in hypotonic solution.
Define these terms i) Turgor pressure ii) wall pressure iii) Osmotic potential.
Explain the following terms relating to cell is various solutions.
Plasmolysis ii) Haemolysis iii) turgidity. Iv) Crenation v) Flaccid.
A. a) i) Hypertonic solution: This is a solution with high concentration of solute molecule than surrounding region.
Hypotonic — Is a lowly concentrated solution compared to surrounding region.
Isotonic solution — Is a solution with same concentration as surrounding region.
b) i) Plant cell when placed in hypotonic solution will gain water, bulge out and become Turgid
An animal cell when place in hypotonic solution will gain water and burst through Haemolysis.
Plant cell do not burst because they have a tough cell wall.
c) i) Turgor- pressure — This is out ward pressure excreted by water within the cell.
Wall pressure — Is hidden pressure that opposes turgor pressure. It is generated by cell wall.
Osmotic potential — This is the tendency of a cell to draw in water.
d) i) Plasmolysis — This is when a plant cell loose water and shrinks.
ii) Haemolysis — This is the bursting of red blood cells when placed in hypotonic solution.
Q. A. student set — up the apparatus below to investigate osmosis.
What will happen after sometimes.
What does visking tubing represent in a living cell?
Name two process that depend on above process.
A. i) After sometimes, the visking tubing will swell and bulge outward due to water intake.
Q.
ii) visking tubing represents a cell membrane Reabsorption of water is kidney.
Absorption of water and mineral salt
A student set —up the experiment below to show osmosis in living tissues


A. i) Water moved from the beaker into scooped potato through osmosis. In the beaker we have high concentrations of solvent molecule than is sugar solution.
If the potato was boiled, water could not have moved to scooped part because permeability could have being killed.
The live potato acts are semi-permeable membrane.
Q. Explain why amoeba, paramecium can survive in flesh water yet they do not burst.
A. They have contractile vacuole which helps to remove excess water.
Turgidly — A Term used to describe a cell that have taken in water and is bulging
outward.
Crenation — is shrinking of an animal cell when placed in hypertonic solution.
Flaccid — Is a plant cell placed in hypertonic solution in which cell membrane has drawn inwards.
Q. a) What is the effect of HIV on white blood cells.
b) Explain why a person with blood group B cannot donate blood to person with blood group A.
c) What is agglutination
d) What is antigen, antibody? e) Which blood group is called?
Universal donor.
Universal recipient.
1) Give a reason why blood group 0 can give blood to any blood group.
i) Give conditions that can lead to blood transfusion
ii) What precautions needs to be taken before blood transfusion.
What is rhesus factor?
What will happen if rhesus +ve mother give birth to rhesus -ve positive child?
In 1628, English doctor William Harvey published full account of how blood circulates around the body.
A. A) HIV Virus attack and make copies of new HIV from existing white blood cells. This decrease the amount of white blood cells thus lowering body immunity.
A person with blood group B cannot denote blood to a person with blood group A Because, Blood group B contain antigen b and antibody a while blood group A has antigen a and
Antibody b . When antigen b meet antigen b agglutination occurs.
Agglutination is clamping together of blood when corresponding antigen and antibody
meet.
Antigen is a protein found on surface of red blood cells they determine blood groups
Antibody is protein found on blood plasma. It can also be manufactured by lymphocytes.
Blood group 0= universal donor Blood group AB universal receipt
Blood group 0 can give blood to any blood group because it contains none of antigen, therefore no likelihood of agglutination occurring.
i) conditions that can necessitate blood transfusion are;
- Loss of Blood after an accident
- Prolonged sickness, leading to low blood level
- Anaemia
- Loss of blood during operation or during birth
ii) Precautions to be taken during blood transfusion?
Screen blood to check if it has other diseases e.g malaria, HIV
The age of donor should be above sixteen years and below 60.
Blood should be taken from vein and not artery
The donor should be healthy
Blood group of donor should be compatible with that of the recipient.
h) Rhesus factor is an extra antigen found on blood cells of some individual it is also called antigen "D"
I) If Rhesus +ve mother gives births to rhesus -Ve Child antigens will cross from mother to child, causing production of antibodies. The first pregnancy there wont be enough antibodies and the child will survive. However in subsequent pregnancies the child dies because antibodies are many leading to severe agglutination.
a) i) Mention components of blood.
ii) Give the function of blood.
iii) Which blood component is concerned with?
Defending the body from diseases.
Preventing excessive bleeding after injury
Transport of oxygen.
Differentiate between Granulocytes and lymphocytes
Give adaptations of erythrocytes to their functions
What is plasma, give functions blood plasma b) Where are the following blood cells manufactured?
i) Erythrocytes (ii) Leucocytes.
A. i) Blood consists of, white blood cells, red blood cells platelets, plasma hormones dissolved gases, urea,mineral salts.
ii) Functions blood.
Transport of oxygen from lungs to tissues
Transport of carbon dioxide from tissue to lungs.
Transport of digested food from intestines to tissue.
Transport nitrogenous wastes from liver to kidney.
Transport of hormones from gland to effectors
White blood cell.
Platelets
Red blood cells. Granulocytes have ability to change shape, thus easily engulf pathogens
Adaptations of erythrocytes
Lack nucleus to create space for haemoglobin
Contain hemoglobin which carry oxygen
Have no shape so that they can squeeze between capillaries
Have biconcave shape to carry oxygen.
a) Plasma is the liquid part of blood yellow in color
Plasma plays the following roles;
Transport carbon dioxide in form of carbonic acid
Transport food and hormones
Regulate body temperature
b) Erythrocytes are made in spleen and bone marrow of long bone
Leucocytes are made in bone marrow of short bones
Q. a) Differentiate between the following terms
Double and single circulation
Systemic and Pulmonary circulation
What is blood pressure?
How do capillaries differ from other blood vessels in their structure and function
Describe the path taken by a molecule of glucose from the time it is absorbed in small intestines, and path taken by molecule of oxygen absorbed in lungs to the time when they both meet in a muscle cell of the leg.
A a) Double Circulation occur when blood passes through heart twice to complete one circulatory cycle.
Single circulation is when blood passes through heart once to complete on circulatory cycle - Systemic Circulation this is heart — lung — body heart circulation, blood passes through the heart twice.
Pulmonary circulation — is when blood moves from heart to lungs to back to heart.
Blood pressure is the pressure exerted at the arteries during contraction and relaxation. It is measured in beats per minute.
Capillaries have one cell thick wall for diffusion of substances. Their function is to aid in exchange of substances.
d) Glucose molecule moves from intestines into liver through hepatic portal vein, from liver it goes to venacava through hepatic vein then to right auricle, right pulmonary artery the lungs, pulmonary artery to left atria, left ventricle to aorta, to arteries to body muscles. Molecule of oxygen from lung goes to pulmonary vein, and then to left atrium, left ventricle, aorta, to arteries and to muscles.
Human body contains about 100,000km of blood vessels. Arteries take blood away from the heart while veins take blood to the heart.
Q (a) Give the following.
A blood vessels that collect blood from lower parts of the body
Valves that control flow of blood left ventricles and left auricle.
Valves found at the base of pulmonary artery
Valves found between right auricle and right ventricle
Artery which supplies blood to interstices.
The vein that carry blood from wall of heart.
(b) Give the adaptation of the heart.
A
Inferior vena cava
Bicuspid valve
Semi- lunar valves Tricuspid valve
Carotid artery Coronary vein
(b) Adaptation of heart.
Its wall is made of muscle called cardiac, which do not fatigue
It is supplied by blood vessels called coronary arteries/veins
Have valves which control flow of blood
Have tendons which help to open and close the heart chambers.
Left ventricle is muscular to pump to all parts of the body.
Q (a) Give a reason for the following;
Blood capillaries are made of single — celled porous wall.
Blood vessels have smooth endothelium
Arteries have more muscular wall than veins
The lumen of arteries is smoother than that of veins.
Left ventricle is muscular than right ventricle.
Veins have valves while arteries do not.
Blood in arteries flow in pulses while in veins it flows smoothly.
(b) Give factors that aid in movement of blood in veins.
c) The diagram represents structure of heart


Name parts A to K)
Which Which blood vessels carry blood rich in oxygen?
Explain differences in thickness of chamber I and K
Which part pumps blood to arteries?
Put the followings in correct order; (a) blood enters arteries (b) Ventricles contract (c) atria contract (d) Ventricle relax (e) blood enters ventricles (f) Semi lunar valves close. (g) Tri- and Bicuspid valves close. (d) Why is a person whose heart valves are damaged by disease unable to take part in active sport?
A (a) — This is to enable diffusion of substance such as food and gases to take place.
Smooth endothelium help to reduce friction as blood passes through artery.
Artery has muscular wall than veins to withstand pressure generated from the heart.
Arteries have small lumen so as to prevent them from bursting and also maintain pressure.
Left ventricle is muscular than right ventricle because it pumps blood to furthest parts of the body.
Veins have valves because blood flow with low pressure to prevent it from going backward. Because blood flow with high pressure in arteries, it creates pulses.
b) Factors that assist in movement of blood in veins
- Presence of valves which prevent back flow of blood.
- Muscular contractions which squeezes blood.
c) i) Parts A - Bicuspid valve B. Pulmonary vein C. Left auricle D vena cava E. Aorta F. left ventricle G Eventide H. septum I. wall of left ventricle J. Semi-lunar valves.
Part B
Chamber I carry blood to all body parts, hence it is thicker than chamber k which carry blood to lungs.
Part F pumps blood to arteries.
v) Atria contract, ventricle relax Blood enters ventricle, Tri — and Bicuspid valves close, ventricle contract blood enters arteries, semi-lunar valves close.
d) Person whose heart valves are damaged is unable to take part in active sports because blood takes long to go to heart and then to lungs for oxygenation
Q. a) Mention the ailments of circulatory stem?
b) Explain how lymph is formed?
c) i) Name blood vessels that takes lymph back to blood stream
How does lymph flow in lymph vessels?
Give the constituent of lymph fluid
d) Give function of lymphatic system.
e) Mention disorders of lymphatic system.
f) explain the mechanism of blood clotting.
A a) Disorders of circulatory system
- Hypertension - Sickle- cell anemia
- leukemia - Diabetes
b) Lymph is formed through filtration at end of capillaries Blood pressure in capillaries cause some materials to come out of blood with water and enter tissue space forming lymph.
c) i) Subclavian vein
Contraction of skeletal muscles squeezes lymph in lymph vessels aiding in movement
Lymph consists of water dissolved food substances, salt,wastes, hormones among others.
d) Function of lymph
- Transport of substance
- Defend of body from diseases (lymphocyte)
- Regulation of temperature.
e) Disorder of lymphatic system
Oedema - swelling
Elephantiasis
Hypertension


f). When a blood vessel is injured, thromboplastin, coverts prothrombin to thrombi. Thrombin, converts fibrinogen to fibrin. Fibrin forms a meshwork of fibres which prevents further loss of blood. Thromboplastin also neutralizes heparin which normally prevents blood from clotting while in the vessels.
Q The diagram below certain structure of plant parts A and B




Name structure a and b.
What is part A and B
Give function of part A and B
Give the difference between xylem vessels and phloem tissue.
Name the process by which water is absorbed into the plant.
Study the diagram below and answer question that follow.






Name parts A, B, C and D.
Using an arrow show how water moves in xylem vessel.
Explain how water moves from point A to part D.
What would happen to leaves of a plant which was losing water by transpiration faster than it was taking it up from the roots?
In what two ways does sunlight increase the rate of transpiration?
Name other parts of plants where transpiration may take place.
If a ring of bark is cut from round the circumferences of a tree trunk the tree dies; however xylem continues to carry water up the stem. Explain why the plant dies.
If the roots hairs take up water from the soil by osmosis, what would you expect to happen if so much nitrate fertilizer was put in the soil that water become stronger solution than cell sap of root hairs?
What is photometer?
A. a) Dicot root b) monocot root
Part A = xylem B = Phloem.
A- Transport of water and mineral salt the soil up to leave
B- Phloem — Transport of manufactured from leaves to other of plants.
b) — Xylem transport water and mineral salt from soil to leaves. Phloem transport manufactured food from leaves to other parts of body of the plant.


Phloem has sieve tube and are lignified
Xylem have bordered pits and perforated ends
c) Osmosis
d) i) A-root hair cell
b) epidermal cell
c) cortex
d) xylem
ii) see on the diagram
Water enters root hair by osmosis. Once the area is saturated with water it moves adjacent cells by similar process until it reaches the xylem where it is conducted upward.
e) -The plants will wilt - curly its leaves
1) - Provides kinetic energy for molecules
- Assist in opening stomata so the water can escape
Lenticels
- Cork cell
Removed ring cuts supply of food to plant leading to its death.
Reverse osmosis water will come from the plant to the soil leading to wilting of the plant
Photometer is an instrument used to measure transpiration
Q. (a) Differentiate Between
i) Transpiration and Translocation
ii) Transpiration and gutation
(b) Mention and explain forces involved in water uptake (c ) What is transpiration pull?
Transpiration is a necessary evil. Discuss.
What factors affect rate of transpiration.
A. (a) i) Transpiration is the loss of water in form of water vapour from plant leaves, Translocation - is the transport of food from leaves to all parts of plants.
- Gutation is the loss of water in form of liquid from stems of plants.
b) Forces of water uptake include
I) Root pressure — This is hidden pressure which force water upward and originates from roots.
- Transpiration pull- Continuous upward movement of water due to continuous loss of water from leaves
Capillarity — Narrowness of capillaries makes water rise up the xylem tubules
- Adhesion — Are forces between molecules of different types
Cohesion — Are forces of attraction between molecules of same kind
d) Transpiration has both advantages and disadvantages Advantages of transpiration
Enable plants loose excess, unwanted water
Brings about cooling effect to plants.
Brings about water uptake.
Disadvantage
It can result to wilting of plant if there is no enough water in soil
e) Factors affecting transpiration rate
Temperature
Humidity
Leaf age
Distribution of stomata
Exhalation.
- Ribs and sternum lowered by relaxation of intercostals muscles and gravity.
- Diaphragm relaxes and returns to normal dome shape position.
- Volume of thoracic cavity decrease. - Pressure in thoracic cavity increases - Air is forced out of the lungs, to equalize the pressure.
f) Once air rich in oxygen enters alveolus, oxygen diffuses into blood capillaries while carbon dioxide diffuses from blood and enters alveolus space and is exhaled out.
Q. a) Explain why it is health to breathe through nose and not mouth
Why is not advisable to sleep in a poorly ventilated room with charcoal burning?
Mention factors that affect breathing rate
TOPIC : 8  BALANCE OF NATURE

P CLASS="western" ALIGN=CENTER STYLE="margin-top: 0.08in; margin-bottom: 0.28in"> CHAPTER 8
BALANCE OF NATURE
KEY TERMS AND CONCEPTS
Natural environment- this is made up of living and non-living thins that occur naturally on earth.
Ecosystem- this refers to natural unit made up of living and non-living things.
Biotic component of the environment- thiese refers to living organisms in an environment.
Predator- an organism that kills another living organism for food.
Prey- this is a living organism that is hunted and killed for food.
Parasites- organism that depends on other organism called host for food and harms them.
Competition- occurs when living organism in a community or population need the same food.
Abiotic factors- these are non-living components of the environment.
Water cycle- this refers to how water circulates in the environment
Carbon cycle- this is a biochemical cycle in the environment where carbon dioxide is taken up from the atmosphere and incorporated into plant tissues during photosynthesis
Nitrogen cycle- is a biochemical cycle in the environment whereby nitrates in the soil are taken up by the plant roots and may pass along food chains into animals.
Symbiosis- is a relationship whereby there is a close association between living organism in terms of feeding.
Mutualism- a feeding relationship whereby two organism benefits each other
Commnsalism- this is an interaction that is beneficial to one organism and neutral to the other organism.
Neutralism- this refers to lack of interaction between two living organism.
Synnecrosis- this is a feeding relationship that is detrimental to both organisms.
Amensalism- this is a relationship that is harmful to one organism but neutral to the other organism.
Trophic level- this is feeding position an organism occupies in a food chain.
Food chain- this is a linear representation of flow of nutrients and energy.
Food web- this is interconnected food chains that shows in a clear picture how energy flow in an ecosystem
Nature comprises of living things and non-living things.
The living part of nature is known as biotic component of the environment while the non-living part of the nature is known as abiotic component of the environment.
The term natural environment refers to the immediate surroundings of an organism which include other living things as well as non-living things.
Terms used to describe a natural environment
(a) Ecology (b) Environment
(c) Biosphere (d) Biome
(e)Ecosystem (f) Community
Ecology
Ecology is a branch of Biology, which deals with the inter-relationship between living organisms and their surroundings. A person who studies ecology is called an ecologist.
Environment
This is the immediate surroundings of an organism, which affect it and with which it may interact. The environment of organisms include both the living and non-living things.
Biosphere
Biosphere is the part of the planet Earth, which is inhabited by living organisms.
This includes the land, the waters and air. It is also known as ecosphere.
Biome
This is a large area of the earths surface, which has particular climatic factors and characteristic flora and fauna examples include savanna grasslands, deserts, tropical forests, temperate forests and tundra. Flora means plants while fauna means animals.
Ecosystem
An ecosystem is a natural unit composed of both biotic and abiotic factors, which interact with each other to form a stable self- sustaining system.
A pond, lake forest a swamp and sea shore are examples of ecosystem.
Community
Community is a group of organisms belonging to different species living in the same area.
For example, in a pond, the community includes the fish, insects, molluscs, protozoa, algae and aquatic plants.


Components of the environment
There are two components of environment namely abiotic components of the environment and biotic components of the environment.
Abiotic component of environment
These are the non-living factors. They are also known as physical factors.
These factors are grouped into three categories for easy study namely climatic factors, topographic factors and edaphic factors.
Climatic- factors
These are the factors which are associated with the prevailing climatic conditions where, the living organism is found.
Climatic factors which affect or influence living organisms include light, temperature, wind, humidity, rainfall and atmospheric pressure.
(b) Topographical factors
These are factors which are related to the structure of the earth. Topographic factors are also known as physiographic factors. They include altitude, slope and exposure


Edaphic factors
Edaphic factors are also known as soil factors. The soil is a substratum in which organisms are found.
The soil provides anchorage, water, air and mineral salts. Edaphic factors include the following soil texture, soil pH, mineral salts and soil water.
Biotic components of the enviromnent
This is part of the environment made up of living things.
Plants and animals are surrounded by and interact with other organisms of the same species as well as those of different species.
The three main biotic components of an ecosystem are producers, consumers and decomposers.
The interactions between living organisms with each other influence the distribution and abundance of any one given species.
Living organisms interact with each other in the following ways:
(a) Competition
Organisms usually compete for scarce (limited) resources such as food, space and light. Two organisms competing for the same resources cannot coexist together, one must die out or migrate.
This principle is called competitive exclusion principle, and states that "two different species cannot occupy the same ecological niche and coexist"
The organisms with suitable structural and behavioural adaptations survive while those without die or migrate. There are two types of competition.
Intraspecific competition
This type of competition exists between members of the same species. For example male lions competing for female mates.
Organisms of the same species compete for food, water, gases (carbon dioxide or oxygen) light, space and mates.
Interspecific competition
This type of competition exists between members of different species. For example lions and leopards compete for food (for example gazelles).
This is a food relationship whereby one organisms kills another for food and feeds on it wholly or in parts.
The one that kills the other is called the predator while the one killed for food is called the prey.
Insectivorous plants such as pitcher plant, which feeds on insects, may also be described as predators.
Predators maintain the population of the prey at a more or less constant level through a negative feed back mechanism.
For example, if the number of predators increases due to favourable environmental conditions, they feed on most of the prey.
The population of the prey is reduced. This is followed by starvation and death of the predators due to food shortage.
With the decrease in the number of the predators, the remaining preys reproduce and increase in numbers. The number of predators starts to increase due to the abundance of food.
Adaptations of Predators
The lions, which prey on antelopes, have strong jaws, large claws, strong forelimbs, fast movement and carnassial teeth.
Birds such as hawks and eagles have acute eye sight, fast flight and modified beaks and feet.
The preys on the other hand must posses structural and behavioural adaptations to minimize predation. For example:
Porcupines have spines.
Snakes spit venom.
Antelopes run fast.
Insects lay many eggs to increase the chances of survival.
Stick insects mimic a dry stick.
Chameleon matches its colour with that of the background, a concept known as camouflage.
Parasitism
This is a food relationship whereby an organism obtains its nutrients from the tissues of another organisms.
The organism that feeds this way is called a parasite while the organism from which nutrients are obtained is known as the host.
The parasite obtains food and or shelter from the host.
The host does not benefit from this relationship instead it is harmed. Parasites can be grouped into two depending on where they live.
Ectoparasites
These are parasites that live permanently or temporarily on to the body surface of the host. Examples include ticks, mosquitoes, tsetse flies and lice.
Endoparasites
These are parasites which live inside the host.
Endoparasites may live in cells, for example most viruses and bloodstream, for example plasmodium.
They may also live in tissue fluid and filarial worms.


Symbiosis
Symbiosis is an association of organisms of different species in which the members either benefit or do not lose.
The association may be between two plants, two animals or between a plant and an animal.
Symbiotic relationship may take any of the following forms.
Mutualism
In this association all members benefit from the other. Examples include the following:
Nitrogen fixing bacteria (Rhizobium) and leguminous plant.
The bacteria extract sap from the plant and also gets shelter. The leguminous plant gets nitrates fixed by the bacteria.
Herbivores and cellulose digesting bacteria. Bacteria in the caecum of herbivores secretes cellulase enzyme that digests cellulose to glucose.
The herbivores therefore obtain glucose and bacteria benefit by obtaining food and shelter.
Flowering plants and pollinators.
Flowering plants depend on pollinators such as bees and butter flies for pollination. From this association the insects get nectar (food) while the plant is pollinated.
Lichen is an association of the blue green algae and a fungus. The algae cells are provided with a means of the attachment and obtain water, carbon dioxide and mineral salts from the fungus.
The fungus in return obtains oxygen and carbohydrates made by the algae through photosynthesis.
Commensalism.
In this association, one of the organisms, the commensal, benefits while the other neither loses nor gains.
For examples the Barnacles that attach themselves to the skin of a whale get free ride through nutrient rich waters without harming the whale.
Habitat
Some organisms use other organisms as habitats for example:
Trees provide nesting sites for birds and homes for monkeys and squirrels.
Insects make their homes in all types of plants, from herbs to trees.
Parasites live in or on their host either temporarily or permanently.
Pollination and dispersal
Pollination is the transfer of pollen grains from the anther to the stigma. Dispersal is the scattering of seeds, spores or organisms.
Birds, insects, and some mammals are agents of pollination and dispersal.
Mans activities
Man is the most influential biotic factor in most habitats. Man has transported plants and animals from their places of origin and successfully managed to grow them elsewhere.
He has also contributed to environmental degradation through deforestation, overgrazing, over cultivation, over fishing and pollution.
Importance of natural environment
Living organisms obtain shelter from the natural environment.
A natural environment provides food for the living organisms.
In a natural environment, living organisms are able to reproduce.
In a natural environment, living organisms are able to interact with the environment.
Living things are able to interact and benefit from one another. A natural environment has a mechanism which controls the population of living organisms.
Ecosystems
An ecosystem is a natural unit where living and non-living components of the environment interact with each other to form a stable self-sustaining unit.
The living members of an ecosystem are collectively called a community. An ecological community includes the following:
Producers
Producers are organisms that manufacture their own food. They are also known as the autotrophs. The most common producers in an ecosystem are the green plants.
The green plants and other photosynthetic organisms trap sunlight to manufacture food substances such as carbohydrates. All other organisms in an ecosystem depend directly or indirectly on the food substances made by autotrophs.
Consumers
These are organisms that feed on the autotrophs or on other organisms. Consumers are mostly the animals and are called heterotrophs.
The consumers occupy different feeding levels in an ecosystem as mentioned below.
Primary consumers
These are animals that feed on green plants. They are also known as herbivores. They include cattle, buffaloes, zebras and elephants.
Secondary consumers
These are animals that feed on the herbivores. They are also known as carnivores. They include lions, leopards, cheetah and cats.
There are various orders of carnivores, for example the secondary consumers are called first order carnivores.
Tertiary consumers
These are animals that feed on secondary consumers. They form the second order carnivore.
Quaternary consumers
These are animals that feed on tertiary consumers. They form the third order carnivore.
Figure 8.1 Energy Flow
Energy flow in an ecosystem
The sun is the natural and main source of all energy entering an ecosystem.
The chlorophyll of the green plants traps the sunlight, which is converted to chemical energy during photosynthesis.
The food substances made such as glucose are potential energy sources available for the rest of the organism in an ecosystem.
The green plants are therefore referred to as producers. The producers (green plants) are eaten by herbivores, which are also known as primary consumers.
The herbivores, in return are eaten by the first order carnivores which are also known as secondary consumers.
If another animal eats a carnivore, that animal is said to be a quaternary consumer.
Trophic Ievels
In an ecosystem, organisms with the same feeding habits are grouped together to form a feeding level.
Feeding level is referred to as energy level or trophic level. All organisms that manufacture their own food, for example plants are referred to as producers and they occupy the first trophic level.
Herbivores such as cows, goats, sheep, buffaloes and elephants are referred to as primary consumers and they occupy the second trophic level.
Carnivores such as dogs, leopards and lions are referred to as secondary consumers and they occupy the third trophic level.
Animals such as hyenas are referred to as tertiary consumers and they occupy the fourth trophic level.
Animals such as vultures are known as quaternary consumers and they occupy the fifth trophic level.
Energy flow decreases as it moves from one trophic level to the next. Only 10% of the energy is available for organisms in the next trophic level.
The 90% of the energy is unavailable for organisms in the next trophic level because:
Some is lost as heat. Heat is lost during sweating, urinating, exhaling, defecating and evaporation from the body surface.
Not all individuals at each trophic level are eaten. For example, not all grasshoppers are eaten by lizards in the savanna grasslands.
Some of the food is not digested by the consumers and passes out as faeces.
Not all parts of the organism are eaten by the consumers or are palatable. For example roots are not eaten by grazing animals.
Some is locked in seabeds or is covered below the ground due to volcanic activities making such energy to be unavailable to the organisms in the next trophic level.
When living organisms die, they are decomposed and broken down into simple substance, which can be absorbed by the plants.
The groups of organisms that decompose dead organic matter are called decomposers. The two main decomposers are the saprophytic fungi and saprophytic bacteria.
Different trophic level depending on what it feeds on. For example, if a leopard feeds on cats, it is put in the 4th trophic level as a second order carnivore.
If the leopard feeds on the herbivore, it is placed in the third trophic level as a first order carnivore.
Interactions of Organisms in the Environment.
Biotic and abiotic factors interact leading to completion of natural cycles. Examples of natural cycles in the environment include the nutrient cycles.
Interactions of organism In the environment
Nutrient cycles involve the recycling of materials in an ecosystem. Every chemical element used by organisms has its own cycles involving producers, consumers, decomposers and non-living part of the environment.
This recycling of materials makes the ecosystems self-sustaining. Energy is non-cyclic. It is constantly lost from the ecosystems, and is constantly replaced by radiant energy from the sun.
In the ecosystems there is no in-flow of new chemical elements, as in the of radiant energy.
Chemical elements in the biosphere cannot be created nor destroyed, they can only be recirculated (recycled) in different chemical forms and combinations.
For example the element of nitrogen is found in amino acids, ammonia, urea and nitrates. The recycling involves nutrients and gases.
The recycling enables re-use of elements by subsequent organisms. If recycling did not take place, the nutrients would not be available and the ecosystem would be disrupted. Nutrient cycles include that of carbon, nitrogen, water, phosphorous and sulphur.
1. Carbon cycle
Carbon is found in the atmosphere in the form of carbon dioxide. Carbon dioxide accounts for 0.03% of the atmospheric gases. Carbon dioxide is absorbed by the autotrophs (producers) such as green plants and used for the synthesis of food substances during photosynthesis.


Figure 8.2 Carbon cycle.
Through photosynthesis, producers combine carbon dioxide with hydrogen to form carbohydrates, which are transformed into protein and fats.
The carbon element in these food substances is transferred to the next trophic level as the consumers eat these food substances.
Carbon element is released back into the atmosphere as carbon compounds through:
Decomposition of dead organic matter. When living organisms die, they decay resulting in the release of the carbon in the form of carbon dioxide.
Respiration. All organisms release carbon dioxide, when they respire. Carbon dioxide is removed during gaseous exchange.
Combustion. Carbon is released in the form of carbon dioxide during burning of organic materials such as wood, charcoal and fossil fuels.
Volcanic activities. During volcanicity gases locked up below the earths surface are released into the atmosphere.
Nitrogen Cycle.
Nitrogen cycle refers to the cycling of nitrogenous compounds in nature. Nitrogen is abundantly available in nature and accounts for 78% of the atmosphere.
This nitrogen in


the atmosphere is not freely available to organisms. Plants absorb nitrogen in the form nitrates.
Nitrogen is needed for the synthesis of proteins. Proteins are the raw materials for growth and repair of an organism body.
Proteins control body activities, for example enzymes control chemical reactions, hormones control body activities, haemoglobin transports oxygen while antibodies fight pathogens.
Nitrogen fixation
Figure 8.3 Nitrogen cycle.
The free nitrogen in the atmosphere must be converted into a form, which can be absorbed by the producers.
Plants take in nitrogen in form of nitrates and to a lesser extent in the form of ammonium compounds.
The following are ways through which nitrogen is converted to nitrates.
Symbiotic nitrogen fixing bacteria.
There are bacteria that live in the root nodules of leguminous plants such as bean plant and pea plant.
These bacteria convert atmospheric nitrogen into ammonia, which is used directly by the leguminous plants to form nitrogen-containing organic compounds such as proteins.
An example of symbiotic nitrogen fixing bacteria is the Rhizobium. The relationship between the Rhizobium and the leguminous plant is called mutualism .
In this relationship both organisms benefit from the other. The bacteria extract sap from the plant and get shelter. The leguminous plants get ammonia fixed by the bacteria.
Free living nitrogen fixing bacteria.
These are non-symbiotic bacteria that are found freely living in the soil.
These bacteria are of two types, bacteria of the genera Azotobacter and Clostridium, which live in the soil and blue-green algae (cyano- bacteria), which are mainly found in water but also occur in the soil.
These bacteria convert atmospheric nitrogen into ammonia. There are other micro organisms which are not bacteria but convert nitrogen. They include Anabaena and Nostoc.


Nitrifying bacteria
The nitrifying bacteria convert ammonia into nitrites. The nitrites are then converted to nitrates.
Some of the nitrifying bacteria convert ammonia to nitrites through a process known as ammonification.
These bacteria include Nitrosomonas and Nitrococcus. Some nitrifying bacteria convert nitrites into nitrates, for example nitrobacteria.
Nitrogen fixation by lightning.
Lightning energy combines atmospheric nitrogen and oxygen to form nitric and nitrous acids. These acids upon reaching the ground combine with other mineral ions to form nitrates.
Denitrifying bacteria
These are bacteria that convert nitrates into nitrites, ammonium compounds and nitrogen gas.
Nitrites and gaseous nitrogen are not freely available to plants. These bacteria live in areas of low oxygen supply.
Therefore they break down nitrates into nitrogen and oxygen gases, where they use oxygen for aerobic respiration.
Examples of denitrifying bacteria include Pseudomonas denitrificans and Theobacillus denitrificans.

Food Chains and Food Webs


Food chains
A food chain is a linear relationship among the organisms of a community, in which each organisms feeds on the one preceding it.
It presents energy flow from one trophic level to the next. Each organism feeds on and therefore derives energy from, the preceding one.
In return it is eaten by, and therefore provides energy to, the one following it. The primary producers such as green plants derive their energy from the sun.
A food chain should always start with a producer.
A food chain may be short or long, but hardly beyond six links. The arrows indicate the direction of energy flow. It can be translated to eaten by, for example Grass →Grasshopper; meaning grass is eaten by grasshopper.
Figure 8.4 food chains.
Food web
This is interconnected food chains. It shows in an elaborate way how organisms interact in form of feeding in the environment.
In food chain, it only indicates that a single organism is being fed upon, while in really sense one organism can be fed by many others.
Figure 8.5 Food web.
Significance of food chains and food webs in real life situations.
Food chains and food webs help to maintain an ecosystem through balancing of the natural environment.
Energy from the sun is utilized and passed on through the trophic levels from the first trophic level to the last trophic level.
Mineral circulation has been made possible through food chains and food webs from one cycle to another cycle.
If there was no decomposition of the organisms, then minerals would not be available for the other organisms in another cycle to utilize.
Food chains and food webs display a clear picture of inter-dependence between the biotic components of the environment.


SUMMARY.


The natural environment consists of all things that occur naturally on earth.
Biotic factors are all the living components of the environments. They include plants, animals and microorganisms.
Abiotic factors are all the living components of the environment. They include soil, altitude, light, temperature, wind, atmospheric pressure and water.
The natural environment s is important because it provides an organism with food, shelter, security and the chance to interact with other organisms.
Living things interact with non living things to complete the water cycle, the carbon cycle and the nitrogen cycle.
The interaction among living organisms can be predatory, competitive or symbiotic.
The symbiotic relationship can be in form of neutralism, mutualism, synnecrosis, amensalism, commensalism and parasitism.
A food chain is a sequence of living things separated by arrows in which each organism is eaten by the next one in the sequence. The arrow points to the eater.
A food web is made up of interconnecting food chains.
Food chains and food webs are important because they facilitate the flow of energy in the environment and help to maintain the balance of the total number of organisms in the environment.


END OF TOPIC QUESTION
i) . Which of the following is not an abiotic component of an ecosystem?
A. Temperature B. Decomposers
C. Humidity D. Light
ii). In parasitism
both the parasite and the host benefit
both the parasite and the host lose
the parasite benefits while the host loses
the parasite loses while the host benefits.
iii). Carbon dioxide is reduced in the atmosphere through
volcanic activities
burning of organic matter
respiration
photosynthesis.
iv). Members of different populations cannot compete for
A. mates B. food
C. space D. light.
v). Which of the following is an example of a mutualistic relationship?
A caterpillar eating tomato plant.
A flowering plant and its pollinators.
A plasmodium inside the human body.
A tick and a cow.
vi). When two organisms live together for their mutual benefit the relationship is called
commensalism
symbiosis
epiphytism
saprophytism.


vii). The green plants in a community-ecologically referred to as
A. consumers B. decompose.
C. producers D. ecosystem


viii). A balanced aquarium contains fish, an aquatic plant and a snail. If the fish were removed, which of the following would probably occur first?
Photosynthesis would increase.
Water would become more acidic.
The plant would die.
The oxygen content of the water would increase.
ix). Man needs food, shelter, clothing, oxygen an energy, all of which come from plants. It can therefore be said that
man and plants are interdependent
man can be independent of plants
through civilization and industrialization man will exhaust plants
none of the above statements is applicable.
x). Which of the following groups of organisms is not a producer?
Planktonic algae.
Cyanobacteria.
Green plants.
Fungi.
2. MATCHING ITEMS QUESTIONS
LIST A
LIST B
Te study of environment in relation to teir environment
Land, water and air
Natural unit tat is composed of biotic and abiotic component wic interact formin a self sustainin unit
Organisms belonin in different species livin in te same area.
Organisms tat are able to reulate teir body temperature
One organism benefit wile te oter neiter ains nor looses.
Organisms wit similar nutritional abits
Symbiotic bacteria found in te root nodules
Linear representation of flow of enery and nutrients
Bacteria involved in ammonification
Azobacter and clostridium
Rizobium
Nitrosomonus and nitrococus
Interconnected food cains
Food cain
Food web
Ecospere
Biosphere
Atmosphere
Ecoloy
Nice
Ecosystem
Community
Abitat
Commensalism
Mutualism
Tropic level
symbiosis


SECTION B
3. An ecologist carried out a survey to estimate the number of organisms in a certain dam. The following table shows the record of the survey.
Organisms
Estimated
number
Microscopic algae
450,000
Small fish
290
Mosquito larvae
5,500
Crocodiles
10
Large fish
160


(a) Which of the above organisms are called the
producers?
primary consumers?
consumers of the last order?
(b) Which organism is likely to get finished first in the dam? Give a reason to support your answer.
(c) Draw a possible food web that shows the energy flow in the dam.
4. Briefly discuss the role played by each of the following in an
ecosystem.
Green plants.
Bacteria and fungi.














Study the pattern below and answer all the questions that follow
Bacteria


Lion Hyena
Gazelle


Cow Zebra




Grass Shrubs


(i) What is name of feeling relationship represented above? ___________________
(ii) Write down any four food chains from the graph above ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________


Name the organisms which is
Secondary consumer _____________________________________
Primary producer _________________________________________


What is the role of bacteria in the pattern above? ___________________________________________________________
(a) Define the meaning of the following terms
(i) Abiotic factors
(ii)Community
(iii) Ecosystem
Commensalism
(b) Write down three significances of food chains and food web
7. Briefly explain the following:
Natural environment
The abiotic component of an environment
The ecosystem


8. Write True for the correct statements and False for the wrong statement.
Natural environment can even in absence of biotic components.
Biotic and a biotic are the only components of an ecosystem.
Heterotropic depend on plants for food.
Fungi are tertiary consumers.
Fungi are tertiary consumers.
In a natural environment a consumer can feed on only are source of food.
Fungi are tertiary consumers.
In a natural environment a consumer can feed on only are source of food.
9. Write short notes on interaction between living organisms.
10. In what ways does the biotic environment depend on the following in an ecosystem?
Soil
Air
Water
11. What is the importance of environmental conservation to ecosystems?
12. Using examples clearly show the difference between food chain food web.
13. Why do we study food chains and food webs?
















BALANCE OF NATURE MULTIPLE CHOICE NECTA QUESTIONS


A group of interdependent organism living in an environment is called
Biosphere
Community
Ecology
Ecosystem
Population (2009)
In a food chain organism with similar nutritional habits constitute a
Biosphere
Community
Food web
Population
Trophic level (2010)
A group of interdependent organism living in an environment is called
Community
Ecology
Ecosystem
Population (2013)
A place where organism are found is known as
Society
Community
Habitat
Niche (2016)
TOPICAL EXAMINATION ON BALANCE OF NATURE
SECTION A MULTIPLE QUESTIONS




SECTION A. 20 MARKS.


Multiple choice questions.
In parasitism
both the parasite and the host benefit
both the parasite and the host lose
the parasite benefits while the host loses
the parasite loses while the host benefits.
Carbon dioxide is reduced in the atmosphere through
volcanic activities
burning of organic matter
respiration
photosynthesis.
iii) A vulture feeds on dead bodies of animals. The vulture is best described as
A. an omnivore B. a carnivore
C. a decomposer D. a scavenger.
iv) Which of the following is an example of a mutualistic relationship?
A caterpillar eating tomato plant.
A flowering plant and its pollinators.
A plasmodium inside the human body.
A tick and a cow.
v) When two organisms live together for their mutual benefit the relationship is called
commensalism
symbiosis
epiphytism
saprophytism.
vi) Which of the following apply in a balanced grassland ecosystem?
There are more consumers than producers.
Decomposers act on producers only.
Producers and consumers are usually in equal numbers.
Producers are more numerous than consumers.
vii) Which of the following groups of organisms is not a producer?
Planktonic algae.
Cyanobacteria.
Green plants.
Fungi.
viii) Light from the sun is never
absorbed by the consumers
reflected back
absorbed by the clouds
absorbed by the producers.
ix) Which of the following ecological statements about cattle and goats is most correct?
Cattle are more efficient in assimilation of food materials taken in as compared to goats.
They are both herbivores but goats are grazers while cattle are browsers.
Cattle are mainly grazers while goats are browsers.
The goats are monogastric while cattle are ruminant.
x) Green plants are known as producers because,
A. They make their food from simple substances
B. They produce green leaves
C. contain fruits and seeds
D. Produce green leaves.


Matching items questions.
LIST A
LIST B
Interconnected food chains
The living components of the environment
Organism that make organic food molecules from carbon dioxide water and inorganic raw materials
A series of organism through which energy is passed in form of food
All living and non living things that occur naturally on earth
Interaction that is beneficial to all organisms involved
Organism occupying the final trophic level
Interaction in which one organism captures, kills and feeds on another
Temperature, wind, light soil water atmospheric pressure and altitude
Converts nitrogen gas into nitrates.
Rhizobium
Azobacter
Biotic component
Predation
Commensalism
Food web
Producers
Neutralism
Water cycle
Food chain
Natural environment
Competition
Carbon cycle
Mutualism
Decomposers
Parasitism.


3. (a) Name two examples of leguminous plants.
(b) The swelling shown on the contain microorganisms.
Name these microorganism
What is the importance of these microorganism the plant?
What term is used to describe the relations between the plant and microorganisms?
4. (a) Give the name of:
The bacteria that cons nitrates into nitrites a ammonia.
A nitrifying bacterium that converts ammonia in nitrites.
A nitrifying bacterium converts nitrates into nitrites.
(b) State two ways through nitrogen is made available plant.
5. a) Briefly explain the following terms;
i) Trophic level
ii) Food chain
food web
b) With examples, briefly explain how the following interactions of living organisms takes place
i) Predation
ii) Parasitism
6. a) With examples state the meaning of abiotic and biotic factors of the environment
B) i) Differentiate the term food chain from trophic level
ii) Construct a food chain by using the organisms below, grass, bacteria, lion and zebra.
7. Briefly discuss the role played by each of the following in an ecosystem.
Green plants.
Bacteria and fungi.
8. An ecologist carried out a survey to estimate the number of organisms in a certain dam. The following table shows the record of the survey.
Organisms
Estimated
number
Microscopic algae
450,000
Small fish
290
Mosquito larvae
5,500
Crocodiles
10
Large fish
160


(a) Which of the above organisms are called the
Producers?
Primary consumers?
Consumers of the last order?
(b) Which organism is likely to get finished first in the dam? Give a reason to support your answer.
(c) Draw a possible food web that shows the energy flow in the dam.






QUESTIONS ANSWER SECTION.
Q 1 a) Differentiate between biotic and abiotic Component.
b) What do you understand by the following the terms
i) Ecosystem
(ii) Natural environment
Ecology
Environment
Biosphere
Biome vii) Community
Habitat
x) Niche
2 c) Differentiate between the following factors which constitutes biotic component of environment i)
climatic factors ii) topographic factors iii) Edaphic factors
d) i) What is competition
ii) Differentiate between intraspecific competition and inter specific competition,
A.
A biotic component - Consists of non-living things in the environment.
b) i) Ecosystem — Is a natural unit composed of both biotic and abiotic factors interacting with each other to form a stable self — sustaining system.
ii) Natural environment — is part of environment that Consists of natural and not man-made components.
Ecology — study of organism in relation to their environment.
Environment — surrounding of an organism that affect it in one way or another.
Biosphere - This is part of earth inhabited by living organisms.
Biome: - Is a large area of earths surface which has a particular climatic factors and characteristic flora and fauna.
Community — Group of organism belonging to different species living in the same area.
Habitat — This is home or place where organism lives.
Niche — Is a specific feeding level in a trophic where an organism occupies.
i) climatic factors associated with prevailing climatic conditions where an organism lives, e. light, temperature.
ii) topographical factors- this relates to the structure of the earth. They are also called physiographic factors eg. Altitude, slope and exposure.
iii) edaphic factors also called sol factors include soil structure, PH, Mineral Salts And Water
d) i) Competition is the struggle of organism for limited resources.
ii) Intraspecific competition exists between members of same species interspecific competitive — exists between members of different species.
Q a) Define the following terms
i) Predation ii) Parasitism iii) symbiosis
Differentiate the following terms
i) Mutualism ii) commensalism
What is a trophic level? Write down main trophic levels of organism
The sun is main source of energy one earth Explain.
Explain why energy decrease as you moves from producers to decomposers in an ecosystem
A a) i) Predation occur when one organism kills another organism for food.
Parasitism is a feeding relationship in which an organism feeds on another organism called host, and ends up harming the host.
Symbiosis. Is a feeding relationship between organisms organism gain
i) Mutualism- Is a form of symbiosis where both of them benefits.
ii) Commensalism. Is a form of symbiosis where two organism interact in feeding, One benefit while the other neither gains nor loose
A tropic level is a group organism with similar feeding habits eg Herbivores.



Tropic level includes producers, primary consumers secondary consumers, Tertiary Consumers, and Decomposers.
Sun is major source of energy on earth because during photosynthesis, the energy from sun is converted into ATP by plant and incorporated in manufactured food. This in then transferred to other trophic levels.
Energy Content of tropic level decrease as you move from produce to decomposers because.
Some is lost as heat
Not all individual in tropic levels are consumed
Some eaten food is not digested
Some food is locked in seabed or in soil and become unavailable.
Q a) Differentiate between a food chains and food web.
Give importance of food chains and food webs.
A Student observed the following organism in an ecosystem, Grass, antelope, zebra, Lion, Leopard, shrubs, Vulture, Bacteria. Draw a food web to show feeding relationship.
d) What are ecological pyramid? Differentiate the terms
Pyramid of biomass
Pyramid of numbers
Pyramid of energy
e) Mention activities which can increase concentration of carbon dioxide in atmosphere.
f) How can free nitrogen be converted into nitrates which can used by plants.
Mention an example of i) nitrifying bacteria
ii) Nitrogen fixing bacteria iii) free-living bacteria
iv) Denitrifying bacteria
Define the terms. i) ammonification ii) Denitrification
A a) A food chain is a linear representation of flow of energy and nutrients. A food web consists of very many interconnected food chains.
b) Importance of food chains and food web
Help to balance natural environment
Help in distributing energy from sun into trophic level.
Mineral elements can be circulated
Gives a clear picture of interdependence between biotic and biotic components.
Cheetah is the fastest land animal. It can reach a speed of 110km/h by taking strides of up to 7m long
d) Ecological pyramid are diagram used to show how energy charges, weight, and mass of organism vary as one more from one tropic level to another.
Pyramid of Biomass- This is the total mass (weight) of all Organisms in a given area.
Pyramid of numbers. Is a diagrammatic representation of number of individuals occurring in each trophic level of a good chain
Pyramid of energy. Is a diagrammatic representation of energy flow through a food chain
e) Carbon oxide is increased by
Decomposition of organic matter
Respiration
Combustion
Volcanic activities.
f) Free nitrogen is converted into nitro nitrate by
i) Lightening ii) Activities of fixing bacteria
g) i) Nitrogen fixing bacteria —e.g. Rhizobium — symbiotic Azotobacter and clostridium — free living.
Nitrifying bacteria e.g. — Nitrosomonas and nitrococcus.
Denitrifying bacteria — Pseudomonas denitrificans and Thiobacillus denitrificans.
h) i) Ammonification. This is the process by which ammonia is converted into nitrites.
ii) Dentrification- This is the conversion of nitrates into nitrogen, nitrites and ammonia compound.
Q. a) Why are green plants called primary producer?
b) The schematic diagram below represents a cycle of material in a given ecosystem.










IV






III








II
RAW MATERIALS
I









i) What tropic level do numbers I — IV represent?
ii) What is the initial source of energy in this ecosystem?
c) I explain the following terms are used in ecology.
Autecology
Synecology
II Describe the follow of energy through an ecosystem
d) In ecological study a student drew food web for savanna grassland are shown below
Isolate food chain where marabou stork is the tertiary consumer.
Give the niches of the following in food web
i) Eagle ii) Green plants.
What would happen if all antelopes were removed from the ecosystem?
What is the primary source of energy in this ecosystem?
A. a) Green plants are called primary produces because they make their own food, which is available to all other organisms.
b) i) I — Decomposer
III- Primary Consumer
II -Producer
IV -Secondary consumer
ii) Initial source is sunlight.
Autecology - study of particular species in relation to environment.
iii) Synecology - study of different populations in relation to the environment.










ESSAY QUESTIONS.
a) Discuss how nutrients and energy flow in ecosystem.
b) The amounts of canon dioxide remain at 0.03% explain how this is maintained.
c) Use a well labeled diagram, explain how nitrogen is recycled.
d) Discuss role of microorganism is nitrogen cycle.




TOPIC : 9  GASEOUS EXCHANGE AND REPIRATION IN MAMMALS



CHAPTER 9
GASEOUS EXCHANGE AND RESPIRATION IN MAMMALS
KEY TERMS AND CONCEPTS.
Gaseous exchange- This is the movement of respiratory gases-oxygen and carbondioxide across the respiratory surface.
Respiratory surface- these are specialized organs for gaseous exchange
Inhalation- this is taking in of air
Exhalation- this is the taking out of respiratory gases
Oxyhaemoglobin- a compound formed when oxygen combines with haemoglobin.
Carbaminohaemoglobin- this is a compound that is formed when carbon dioxide combineswith haemoglobin.
Lenticels- areas of loose cells where gaseous exchange takes place.
Glycolysis- a stage of respiration in which a three carbon atom compound is formed from glucose.
Aerobic respiration- this is the break down of food in presence of oxygen to produce energy.
Anaerobic respiration- this is the break down of food in absence of oxygen to produce energy.
Kreb’s cycle- it is also called nitric acid cycle, in this cycle, it involves the formation of a six carbon molecule from a two molecule compound.
Fermentation- this is the breakdown of glucose by bacteria or fungi to form alcohol.
Oxygen debt- this is the amount of oxygen required to be supplied in the body so as to get rid of lactic acid.
Anaerobes- are organisms that respire anaerobically
Obligate anaerobes- are organism that can only live and respire in the absence of oxygen.
Facultative anaerobes- these are organism which respire in both presence and absence of oxygen.
Carboxyhaemoglobin- a deadly compound formed when carbon monoxide combines with haemoglobin.
Counter current flow- blood and water flows in different direction to maximize the absorption of oxygen.


Gaseous exchange
Gaseous exchange is the movement of oxygen and carbon dioxide across a respiratory surface. Unicellular organisms carry out gaseous exchange by diffusion across the cell membrane. Large organisms cannot carry out diffusion efficiently so they have developed specialized organs for gaseous exchange. These are called respiratory surfaces.


Characteristics of respiratory surfaces
They are thin to reduce the diffusion distance.
They are moist to dissolve gases so that they diffuse in solution form.
They are highly branched, folded or flattened in order to increase the surface area for gaseous exchange.
They are close to an efficient transport and exchange system so that gases can be taken to and from the cells easily.
They are well ventilated so that gases can pass through them easily.


COMPONENTS OF GASEOUS EXCHANGE
The components of the gaseous exchange system in mammals include the nostril, trachea, lungs, intercostal muscles, diaphragm and ribs.
The mechanism of gaseous exchange in mammals.
Gaseous exchange in mammals happens as a result of inhalation and exhalation.
Inhalation is breathing in air into the lungs.
Exhalation is breathing out air from the lungs.
During inhalation the muscles of the diaphragm contract, pulling the diaphragm downwards.
As this happens, the external intercostal muscles contract and pull the ribcage upwards and outwards.
The result of these movements is an increase in the volume and a decrease in the air pressure of the thorax. This makes air rush into the lungs through the nostrils, trachea and bronchioles.
During exhalation, the muscles of the diaphragm relax and the diaphragm resumes its dome shape.
Figure 9.1 Chest Cavity
The external intercostal muscles relax, pulling the ribcage inwards and downwards. As a result, the volume of the thorax decreases and the pressure inside it increases. This forces air out through the bronchioles, trachea and nostrils.
Gaseous exchange across the alveolus
The actual exchange of oxygen and carbon dioxide takes place in the alveoli. One mammalian lung has millions of alveoli.
The alveoli are surrounded by a network of capillaries.
The oxygen is then transported to the tissues. Once in the tissues, the oxyhaemoglobin breaks down to release oxygen and haemoglobin.
The tissues use oxygen and release carbon dioxide.
Figure 9.2 Gaseous exchange in Alveolus.
This causes the levels of carbon dioxide to become higher in the tissues than in the blood. Carbon dioxide therefore diffuses into the blood in the capillaries and combines with haemoglobin to form carbaminohaemoglobin.
The capillaries transport carbon dioxide in this form to the alveoli. The concentration of carbon dioxide is higher in the blood in the capillaries than in the air in the alveoli.
Carbon dioxide therefore diffuses from the capillaries into the alveoli. It is then transported through the bronchioles, trachea, glottis, pharynx and finally nostrils into the atmosphere.
Carbon dioxide is also transported in form of weak carbonic acid dissolved in water
Factors affecting the rate of gaseous exchange
Concentration of carbon dioxide
High concentration of carbon dioxide in the blood increases the rate of gaseous exchange.
This provides the tissues with adequate amounts of oxygen and lower carbon dioxide concentration in the blood.
High level of carbon dioxide in blood will thus trigger faster breathing mechanism.


Concentration of haemoglobin
Haemoglobin is responsible for the transportation of gases from the lungs to the tissues and back.
Efficient transportation of gases takes place when the body has adequate amounts of haemoglobin.
When a person is anaemic, the body has a low concentration of haemoglobin. Only small amounts of oxygen can be transported at a time. As a result, the rate of gaseous exchange has to increase so that the tissues get adequate amounts of oxygen.
Anaemia including sickle cell anaemia can contribute to low level hemoglobin
Physical activity
A more active body requires more oxygen than a less active body. As a result, gaseous exchange takes place faster when there is increased body activity.
Health status of the body
The rate of gaseous exchange increases when somebody is sick.
This is as a result of increased metabolism by the liver in order to remove the toxins released by disease-causing microorganisms or break down the drugs taken.
Certain diseases also make the body weak and cause slowing down of the breathing process.
Altitude
Altitude is the height above sea level. At high altitudes, the concentration of oxygen is lower compared to low altitudes.
Breathing is therefore faster at high altitudes. At high altitudes, there is also decreased atmospheric pressure.
This makes breathing difficult. Organisms therefore have to breathe in faster in order to get enough oxygen.
Age
Young people are generally more active than old people. Also, a lot of growth processes take place in the bodies of young people.
This increases the demand for oxygen and therefore increases the breathing rate.
Gaseous exchange in plants
In plants, gaseous exchange mostly takes place through the stomata on the leaves and lenticels on the stein.
Some plants such as mangrove also carry out gaseous exchange through breathing roots.
Gaseous exchange in the leaves
Gaseous exchange mostly takes place in the air spaces in the spongy mesophyll.
Atmospheric air moves into and out of the leaf through the stomata.
During the day, green plants carry out photosynthesis to produce glucose.
This takes place within the guard cells that surround the stomata. As a result, the cell sap of guard cells becomes hypertonic and draws in water from the neighboring cells by osmosis.
The guard cells become turgid and the stomata open. Air from the atmosphere enters into the air spaces in the spongy mesophyll.
The cells next to the air spaces have more oxygen (produced by the cells during photosynthesis) but less carbon dioxide (used up during photosynthesis).
Figure 9.3 The guard Cell
On the other hand, carbon dioxide is more in the air within the air spaces but oxygen is less.
Carbon dioxide and oxygen diffuse in opposite directions depending on their concentration gradients.
The carbon dioxide diffuses to neighbouring cells until it reaches the site for photosynthesis. Oxygen moves out through the open stomata into the atmosphere.
At night, there is no light, therefore photosynthesis ceases. No glucose is produced, therefore the guard cells do not absorb water by osmosis. Hence, the stomata remain partially closed.
However, respiration takes place in plants at night. The partially open stomata allow in small amounts of air which accumulate in the air spaces. There is more oxygen and less carbon dioxide in the air spaces compared to the plant cells.
Oxygen moves into the plant cells while carbon dioxide moves into the air spaces and eventually into the atmosphere through the partially open stomata. This explains why plants produce carbon dioxide at night and oxygen during the day.
Gaseous exchange through the lenticels
Lenticels are made up of loosely packed cork cells located on the bark of woody stems and roots. They are small pores through which gaseous exchange occurs.
The loose arrangement of the cells facilitates the movement of gases between them. The cells have a thin layer of moisture so that gases diffuse in and out while in solution form.

Figure 9.4 Lenticels
At night, there is a higher concentration of oxygen in the air spaces between the cork cells than in the cells themselves. Oxygen therefore diffuses into the cells surrounding the lenticel. The cells use oxygen for respiration and release carbon dioxide in the process.
Thus, the concentration of carbon dioxide in the cells become higher than in the air spaces. Carbon dioxide therefore diffuses out through the cells into the air spaces and then out through the lenticel. The opposite happens during the day.
Gaseous exchange through the roots
This occurs through breathing roots. Plants with breathing roots have a very thin epidermal layer which enables the root to carry out gaseous exchange.
Oxygen is at a higher concentration in the atmosphere than in the root cells. Therefore, oxygen diffuses into the root cells through the epidermis.
During respiration, the plant uses oxygen and releases carbon dioxide. This causes the concentration of carbon dioxide in the root cells to be higher than in the atmosphere. Carbon dioxide diffuses from the root cells into the atmosphere through the epidermis.
Importance of gaseous exchange in plants
1. It enables plants to obtain carbon dioxide, which is one of the raw materials necessary for photosynthesis.
Plants obtain oxygen which is necessary for the production of energy. Energy is produced during respiration.
It enables the plant to eliminate excess carbon dioxide at night of which if left, will harm the plant.
Respiration
Respiration is the process by which food substances are broken down to provide energy. It is controlled by enzymes.
Enzymes are substances that affect the rate at which a reaction occurs but are not used up in the reaction themselves.
Respiration takes place in the mitochondria of the plant cells.
There are two types of respiration: aerobic respiration and anaerobic respiration.
Aerobic respiration
This is a type of respiration whereby oxygen is used to break down glucose, releasing energy, carbon dioxide and water.
The chemical reaction for aerobic respiration is:
C6I-11206 + 6 02 → 6 CO2 + 6 H2O + Energy
Glucose oxygen carbon dioxide water
The energy produced is in the form of ATP (adenosine triphosphate). Thirty-eight molecules of ATP are produced at the end of the aerobic respiration.
Aerobic respiration takes place in two stages: glycolysis and Krebs cycle.
Glycolysis takes place in the cytoplasm. It does not require oxygen so it is a phase that is common for both aerobic and anaerobic respiration.
During glycolysis, enzymes break down glucose into a three carbon compound called pyruvic acid. Glycolysis produces 2 molecules of ATP per molecule of glucose. The pyruvic acid can further be broken down in the presence or absence of oxygen.
If there is oxygen, the pyruvic acid proceeds to the next stage of aerobic respiration, which is Krebs cycle. If there is no oxygen, anaerobic respiration occurs.
Note that pyruvic acid passes through a stage where it is decarboxylated (one carbon dioxide molecule removed from it) before going through the Krebs cycle.
Krebs cycle is also called the citric acid cycle. It involves the formation of citric acid molecule (a six carbon) from the two carbon molecule by addition of a four carbon molecule, i.e. oxaloacetic acid in a cyclic process.
Krebs cycle takes place inside the cristae of the anaerobic respiration mitochondria.
Anaerobic respiration takes place in the absence of oxygen.
In plants, anaerobic respiration is also called fermentation. It involves the breaking down of glucose by bacteria or fungi to form alcohol, carbon dioxide and energy. This is represented by the following equation:
C6H1206 → 2 C2H5OH 2+ CO2 + Energy
glucose ethanol carbon dioxide
In animals, anaerobic respiration leads to the formation of lactic acid and energy. This is written as:
C6H1206 → 2 C3H603 + Energy
glucose lactic acid
In animals anaerobic respiration takes place during strenuous activity, for example during sports.
It leads to the accumulation of lactic acid in the muscles. Lactic acid is toxic.
Anaerobic respiration occurs when the bodys oxygen supply does not meet the bodys needs. Therefore, an oxygen debt or oxygen deficit occurs.
This causes the animal to breathe fast and deeply in order to get enough oxygen to convert the lactic acid to carbon dioxide and water. Some of the lactic acid is converted to glucose.
Breathing goes back to normal when the acid has been broken down.
Anaerobes are organisms that respire anaerobically. They include bacteria, yeast and fungi. There are two types of anaerobes:
Obligate anaerobes- which can only live and respire in the absence of oxygen. They die in the presence of oxygen.
Facultative anaerobes- which respire both in the presence and in the absence of oxygen.


Factors affecting the rate of respiration
The rate at which respiration takes place varies depending on the state of an organism.
Hence, respiration is sometimes fast and at other times slow. The following factors affect the rate of respiration:
Temperature
Respiration is controlled by enzymes. The functioning of enzymes is affected by temperature.
The rate of respiration is slow at low temperatures and increases with increase in temperature until the optimal temperature.
Optimal temperature is the temperature at which the enzymes function best. If the temperature is raised above optimal temperature, the enzymes are denatured and the rate of respiration reduces.
Physical Activity
When an organism is involved in a vigorous activity, it requires more energy than when it is at rest.
A human being requires less energy when sitting than when taking part in a race.
Therefore, the rate of respiration changes to suit the needs of the organisms physical activity.
Size
Small organisms lose heat faster than big organisms. This is because small organisms have a larger surface area to volume ratio. Heat is a form of energy. Therefore, small organisms need to respire faster than large organisms to replace the energy lost through heat.
NB. A thin person is likely to feel hungry faster than a fat person, this is because a thin person has a large surface area to volume ratio compared to thin person.


Age
Generally, young organisms respire faster than older organisms. This is because they need energy to grow. In addition, young organisms are more active than old organisms.
Health
When we are sick, the rate of respiration increases so as to remove the toxic materials produced by the pathogens in our bodies.
Infections and diseases of the respiratory system
There are several airborne infections which affect the human respiratory system. The common ones are influenza, pneumonia, common cold and tuberculosis.
Most of the airborne infections are as a result of close contact with an infected person.
When the sick person breathes out, coughs or sneezes, the pathogens are released into the air.
Thus, person who is close by may catch the infection. Sometimes, droplets may infect bedding, clothes and surfaces used by the sick person.
Airborne infections can be controlled by isolation of the infected patient, proper disposal of infected secretions such as sputum, living in a well-ventilated house and avoiding overcrowding, especially in bedrooms.
Pneumonia
Pneumonia is inflammation of the lungs. It is caused by bacteria, viruses, fungi or by inhaling chemical toxins or irritants.
Pneumonia is normally followed by other illnesses such as cold or flu.
Pneumonia can be caused by bacteria, viruses or fungi
In 2015, pneumonia accounted for 16% of all deaths among children.
Signs and symptoms of pneumonia
Fever
Chills
Shortness of breath associated with pain
Increased mucus production
Cough
Prevention and treatment of pneumonia
Staying warm
Immunization
Adequate nutrition
Address environmental factors
Avoiding overcrowded areas
Avoiding cold food or drinks. Hot drinks are preferred more as they loosen secretions
Get treatment as early as possible since it is curable by antibiotics
Bronchitis
Bacteria, viruses and inhaling of irritating substances can cause the lining of the respiratory system to become inflamed.
This causes an infection called bronchitis. Bronchitis can be acute or chronic.
Acute bronchitis
This is caused by whooping cough or recurrent attacks of influenza. Smoking can also cause acute bronchitis.
Signs and symptoms of acute bronchitis
Pain in the chest
Shortness of breath
Slight fever and chills
Rapid breathing
Chest discomfort
Fever
Coughing
Headaches
Prevention and treatment of acute bronchitis
Staying warm. Cold temperatures make the body more susceptible to bacterial infections
Get treatment for all infections as fast as possible


Chronic bronchitis
Chronic bronchitis is caused by heavy smoking and recurrent acute bronchitis. It is a productive cough that lasts at least 3 months, with recurrent bouts occurring at least two consecutive years
Signs and symptoms of chronic bronchitis
Coughing, with the production of thick sputum
Breathing difficulties
Prevention and treatment of chronic bronchitis
Avoid smoking
Avoid very smoky or dusty areas
Live in a well-ventilated house
Keep your body warm
Seek medical help
Asthma
Asthma can be caused by:
Allergic reactions to dust, pollen, spores or animal fur
Hereditary diseases of the respiratory system
Extremely cold weather
Frequent viral or bacterial lung infections
Signs and symptoms of asthma
Narrowing of bronchioles resulting in breathing difficulties and a wheezing or hissing sound when breathing
Excessive production of mucus
Dilation of blood vessels, leading to low blood pressure. Low blood pressure can be fatal
Prevention and treatment of asthma
Avoid allergens (things that cause allergic reactions)
Get treatment for respiratory infections as early as possible
Keep the body warm
Muscle relaxants in the form of sprays, pills and injections are used to prevent the narrowing of the bronchioles
Lung cancer
The main cause of lung cancer is smoking. The nicotine in cigarette smoke stops the cilia in the trachea from expelling foreign materials leading to respiratory infection.
Signs and symptoms of lung cancer
Chest pain
Breathing difficulty
Weight loss
Persistent cough
Abnormal production of mucus
Prevention and treatment of lung cancer
Stop smoking
There is no cure for cancer. However, chemotherapy and physiotherapy are used to control the disease
Emphysema
This is a lung disease which results from destruction of the structures supporting the alveoli leading to their collapse. This significantly reduces the surface area available for gaseous exchange.
Causes of emphysema
Mainly cigarette smoke
Air pollution
Hereditary
Old age
Signs and symptoms of emphysema
Shortness of breath
Coughing
Obstructive lung disease
Difficulties when breathing, especially during exercise
Wheezing during breathing
Prevention and treatment of emphysema
Avoid cigarette smoking and exposure to smoke
Lung surgery is usually done to relieve the symptoms
Use of medical drugs
In severe cases, lung transplant is necessary








GASEOUS EXCHANGE AND RESPIRATION SUMMARY
Gaseous exchange is the exchange of oxygen and carbon dioxide through a respiratory surface.
Features of a gaseous exchange surface are:
Thin membrane
Large surface area
Moist lining
Dense network of capillaries
The structures involved in gaseous exchange in mammals are the nose, mouth, pharynx, glottis, trachea, lungs, bronchioles, alveoli, ribs, pleural membranes and diaphragm.
Gaseous exchange is affected by the amount of haemoglobin in the blood and carbon dioxide concentration.
In plants, gaseous exchange can take place through the stomata in the leaves, lenticels in woody stems or in breathing roots.
Respiration is the process by which food substances are broken down to release energy.
Aerobic respiration takes place in the mitochondria in the presence of oxygen.
Aerobic respiration involves two stages: glycolysis and kreb’s cyle.
Anaerobic respiration takes place in the cytoplasm in the cytoplasm in the absence of oxygen.
Diseases and infection that affect the respiratory system include bronchitis, asthma, pneumonia, tuberculosis, emphysema and influenza.
GASEOUS EXCHANGE IN PLANTS QUESTIONS.
Choose the correct answer from the alternatives given.
The following animals use lungs as their respiratory surface except__________
Spiders
Lizards
Hippopotamus
Chicken
Gaseous exchange in small animals earthworms occurs by________________
Diffusion
Osmosis
Inhalation
Exhalation
Nose for human is like spiracles for__________
Mosquitoes
Scorpions
Frogs
Fish
The following are the characteristics of gaseous exchange surface except ___________
Highly folded
Dense capillary network
Thick membrane
One of the following lists is found in the ribcage­­­­­­­­­­­­­­­­­­­­­­­­­________________
Nostril, trachea and diaphragm
Lungs, intercostals muscles and diaphragm
Lungs, intercostals muscles and diaphragm
Intercostals muscles, trachea and diaphragm
What is the cause of the cramps you feel in your muscles during strenuous exercise?
Lactic acid fermentation
Alcohol fermentation
Chemisiosmotic coupling
Too much oxygen delivery to the muscles
Which of the following is not part of the upper respiratory system?
Esophagus
Pharynx
Nose
All of the above
When we breath in we inhale many gaseous, including oxygen. What is happens to the gaseous that gaseous that the body can not use?
They are exhailed
They are changed into oxygen by the lungs
They circulate through the body and are disposed of later.
They are absorbed into the digestive system and used to create energy.
Which malfunction of the respiratory sytem is the destruction of alveolar walss?
Bronchitis
Pneumonia
Emphysema
Asthma
Which of the following describes pneumonia
Swelling of the throat
Building up of fluids in the lungs
Loss of red blood cells.
Inflammation of the bronchi
xi. Which of the following is not part of the respiratory system of humans?
Lungs
Trachea
Kidney
Alveoli
xii. The chemical equation : glucose + oxygen → carbon dioxide + water + energy, represents___________-
Photosynthesis
Internal respiration
External respiration
Excretion
xiii. Carbon dioxide in the blood is removed from the body through the _____________
Kidney
Lungs
Mouth
Skin
vix. the waste products of respiration are ___________
Glucose and oxygen
Carbon dioxide and water
Carbon dioxide and heat
Oxygen and water
xv. which of the following is the respiratory organ of fish?
Glucose and oxygen
Carbon dioxide and heat
Carbon dioxide and water
Oxygen and water




2. Write true for correct statement and false for wrong statements.
The end walls of the tracheas have holes called pits through which vertical movement of substance occurs.
Movement of substances through tracheas is more efficient than through xylem vessels.
Companion cells have many mitochondria to release energy which is need for transport goes against concentration gradient.
Active transport goes against concentration gradient.
Minerals salts are less concentrated in the roots of plant than in the soil.
3.Match the items in list A With the correct responses in list B.
LIST A
LIST B
Lenticels
Control opening and closing of stomata
Stomata
allow photosynthesis to take place
guard cells
exchange across a respiratory surface
breathing root
exchange of carbon dioxide and oxygen
gaseous exchange
the main site for gaseous exchange and photosynthesis
found in mature woody etems and rooots
gaseous exchange
found mostly in leaves but also in stems of some plants
found in plants growing in water


4. Explain what would happen to plants if :
Chlorophyll were removed from guard cells.
The spongy mesophyll cells were closely packed
The spongy mesophyll cells were closely packed
The outer wall of guard cell is removed
The epidermis of breathing roots is thickened
There was only a limited supply of gaseous in plants.
5.(a) What is respiration?


(b) Describe four factors that affect the rate of respiration
(i) ___________________________________________________
(ii) ___________________________________________________
___________________________________________________
___________________________________________________


(c) Outline the five features of the respiratory surface
(i) ___________________________________________________
(ii) ___________________________________________________
___________________________________________________
……………………………………………………………………………………………………………..
6 . (a) Give the meaning of the following terms
(i) Respiration
(ii) Gaseous exchange
(b) Outline 4 adaptations of respiratory surfaces


7. What is the vascular system?
Briefly describe the components of the vascular system.
Explain the function of the each component of the vascular system.
8. What do you understand by the following terms?
Transpiration pull
Root pressure
capillarity
9. What is a root?
What are the root hairs
Explain the role of root hairs in absorbing water and minerals into the xylem
10. Write short notes on how water moves the roots up to the leaves. Elaborate on the role of the forces involved.
11. What is transpiration?
What is the role of transpiration in plants.
List the factors which affect the transpiration in plants.
List the factories which factors which affect the rate of transpiration in plants.
12.Fill the blanks
Book lung is a
respiratory structure found in ___________
Amphibians use more than one respiratory structure namely __________ and___________
The role of mucus in the inner lining of trachea is _______________
In the lungs, each bronchiole ends up into a tiny sac called__________
Pharynx and nose are connected by ______________
13. Define the following terms:
Inspiration
Gaseous exchange
Expiration
14. Explain the advantages breathing through the nostril rather than the mouth in human being.
15. Outline the changes that occur changes that occur in the ribcage and the diaphragm during inspiration and expiration.
16. The table below shows changes in the composition of inhaled and exhaled air. Study it carefully and answer the questions that follow.
Components
Inhaled air (%)
Exhaled (%)
Oxygen
20.9
16.40
Carbon dioxide
0.03
4.00
Nitrogen
79.01
790.1




Explain why:
The amount of oxygen is decreased.
The amount of carbon dioxide is increased
The amount of nitrogen remains constant.
17. Outline the factors that affect the rate of gaseous exchange in mammals.
18. How are different features of respiratory structure adapted to their functions?




19. Write True for correct statements and False for wrong statements.
Respiration takes place in mitochondria______________
Respiration involves oxidation of an organic compound, the respiratory subtract such as glucose._________
Proteins can only be used in respiration when all carbohydrate and lipids reserves have been used as during pronged starvation.
Anaerobic respiration is often referred to as fermentation._________
Obligate anaerobes (e,g clostridium titanic) which cause microorganisms such use anaerobic respiration as their major sources of energy__________
20. Define the following terms:
Oxygen debt
Breathing
Respiration
21. Briefly distinguish between respiration and breathing.
22. Briefly describe an experiment you would perform to demonstrate or show that exhaled (expired ) air contains carbon dioxide.
23. Mention the products of tissue respiration.
24. State three reasons why respiration and burning are similar Processes?
25. Mention the main gaseous present in
Fish
Man
Spider
Lizards
Cockroach
26. Mention any five known respiratory disease in humans.
27. Briefly describe the breathing mechanism during inhalation and exhalation of air.








SECONDARY EXAMINATION SERIES
TOPICAL EXAMINATION
BIOLOGY FORM 2- GASEOUS EXCHANGE.


SECTION A. 20 MARKS


MULTIPLE CHOICE QUESTIONS.
i) Oxygen passing from the atmosphere into the blood of a mammal takes one of the following routes. Which one?
A. Trachea - bronchi – bronchioles-alveoli
B. Trachea - bronchioles – bronchi-Alveoli
C. Bronchi - bronchioles – trachea-Alveooli
D. Bronchioles - bronchi – trachea-Alveoli


ii) Which of the following sets contains respiratory gases only?
A, Oxygen and argon
Oxygen and carbon dioxide
Hydrogen and argon
Carbon dioxide and hydrogen
iii) Where does gaseous exchange take place in man?
A. Gills B. Trachea
C. Lungs D. Skin
iv) The lungs are enclosed in double membrane known as
plasma lemma
plasma membrane
lung membrane
pleural membrane.


v) The following are characteristics of a respiratory surface, which one is not?
Has a large surface area.
Has a good network of blood capillaries.
Has thick membrane.
Has moist surface.
vi) Where does gaseous exchange take place in a plant?
Spongy mesophyll cells.
Palisade cells.
Guard cells.
Stomata.
vii) Which of the following statements is not true?
A. During the day plants take in carbon dioxide.
During the day plants take in oxygen.
At night plants take in oxygen
At night plants release carbon dioxide.
viii) Terrestrial plants obtain respiratory gases from
the surrounding water
the atmosphere
A and B
none of the above.
ix) The compound in which oxygen is transported is referred to as
oxyhaemoglobin
carboxyhaemoglobin
haemoglobin
haemorrhage.
x) One of the following is not a respiratory surface
A. skin B. nostrils
C. gills D. mouth cavity.
2. Matching items question.


List A
LIST B
Gaseous exchange structure of amoeba.
Gaseous exchange structure of spider
Diffusion of gases in and outside the respiratory surface.
Found in chest cavity and filled with fluid which reduces friction
The form in which oxygen is carried in blood.
Areas with loosely packed cells which allows for gaseous exchange.
The inner membrane of a mitochondrion
The product of anaerobic respiration in animals
The least energy required by the body at rest.
A type of respiration which occurs in the cytoplasm.
Mitochondrion
Cristae
Pleural cavity
Pleural membrane
Cytoplasm
Cell membrane
Spiracles
Book lung
Respiratory quotient
Basal metabolic rate
Lenticels
Cork cells
Matrix
Anaerobic respiration
Lactic acid
Ethanol
Oxyhaemoglobin
carboxyhaemoglobin


SECTION B.


3. (a) Name the structures used for gaseous exchange in the following organisms:
Fish
Mammal
Bird
Grasshopper
Land ( terrestrial) green plants
Spider
Tadpole
Frog
Amoeba
Explain why it is not possible to drown or suffocate a locust or grasshopper by holding its head under water while the remaining part of the body is outside the water.
(a) Explain why a fish suffocates on dry land although atmospheric air contains more oxygen than water.
Give reasons why it is healthier to breathe through the nose than through the mouth.
(a) State the composition of inspired air and expired air in man.
(b) What is the role of the diaphragm during inspiration and expiration.
6. Explain why
It is not healthy to sleep in a closed room with potted plants
It is dangerous to sleep in a poorly ventilated room with a charcoal burner on
One pants during heavy exercises.
7. Explain why;
i) The rate of breathing increases rapidly during exercise
ii) Your breathing rate does not go back to normal as soon as you stop exercising.
8. i) (a) Why is it better to breathe through the nose and not the mouth?
b) Explain what will happen if epiglottis is removed from the body
ii) Briefly explain how breathing takes place in humans.
9. Differentiate between glycolysis and krebs cycle
10. Briefly give the differences between respiration and photosynthesis
RESPIRATION NECTA QUESTIONS


Muscle fatigue in the body is caused by lack of
Carbon dioxide
Pyruvic acid
Oxygen
Lactic acid
Uric acid (2007)
The most essential function of respiration in living organism is
Breathing in and out
The liberation of energy for work
The removal of nitrogenous waste
The liberation of carbon dioxide and water
Taking in oxygen and giving out carbon dioxide (2007)
The following are the products of respiration except
Alcohol, carbon dioxide, and energy
Alcohol, energy, and lactic acid
Carbon dioxide, energy, and lactic acid
Carbon dioxide, energy and water
Glucose, oxygen, and water (2009)
Muscle fatigue in the body is caused by
Lack of carbon dioxide
Lack of lactic acid
Lack of oxygen
Pyruvic acid (2011)
A gaseous exchange in plant does not take place in the
Flowers
Leaves
Roots
Stems (2012)
Aerobic respiration takes place in the presence of
Water
Carbon dioxide
Oxygen
Hydrogen (2014)
The product of anaerobic respiration process in animals is
Uric acid
Lactic acid
Sulfuric acid
Hydrochloric acid (2015)


QUESTION AND ANSWER SECTION.






e) Explain mechanism of ventilation in fish.
A. a) - Spiracles
Lung, skin, mouth
Book lung
Lung
External and internal gills
b) Structure of a Gill
Is a phenomenon where blood and water in gills flow in opposite direction. It increases diffusion rate.
gill bar — supports gills filaments
- Gill filaments forms surface where gaseous exchange takes place. - Lamellae — increase surface area for diffusion of gases
- Gill rakers traps solid food materials in water
During inhalation, mouth is opened and operculum closed, flow of mouth is lowered increasing volume thus lowering pressure. Water flows into mouth and pharynx. The The mouth is the closed and floor of pharynx raised squeezing water out past the gills.
Q. a) Name three structures used for gaseous exchange in adult frogs.
What is the adaptation of skin of frog in gaseous exchange?
Describe the mechanism of gaseous exchange in
i) Buccal cavity ii) Pulmonary / lung
Explain why lower part of a frog mouth moves up and down?
A. a) - Lungs
- skin
- Buccal cavity.
b) The skin of frog is always moist and soft to allow diffusion of gases.
c) Gaseous exchange by Bucccal cavity.
Nostrils are opened
Floor of mouth is lowered
Volume of buccal cavity increase
Pressure decreases
Air is drawn in through buccal cavity.
Floor of buccal cavity is raised
Air is forced out through the nostrils.
iii) Pulmonary ventilation.
An adult frog have lungs used when on land
Air is drawn into buccal cavity as above
Floor of mouth is raised but nostril remain closed
Air is drawn into lungs which inflate
02 gas diffuses into alveolus and enters blood stream while CO2 enter alveoli from blood.
Floor of mouth is lowered increasing the volume and decreasing pressure, air is drawn out of lungs.
Q. a) Give adaptation of mammalian respiratory system
What role does the following play in gaseous exchange?
1) Intercostals muscles ii) Diaphragm
What is the difference in composition of inhaled air and exhaled air?
What is the importance of lungs being located in chest cavity?
Explain the mechanism of breathing in man.
Describe how gaseous exchange occurs in alveolus
A. a) - Have trachea with rings to avoid collapsing.
- Lungs are spongy like to hold a lot of air.
- Chest cavity has internal and external intercostals muscle to aid in movement of air - Have diaphragms which help in breathing.
Intercostals muscles contract raising chest cavity thus decrease pressure which enable air to enter in. Diaphragm — this is a floppy muscles found at lower part of chest cavity it assist in breathing.
Chest cavity offer protection of the lungs from any damage.
e) Mechanism of breathing in man,
- During inhalation,
- Ribs and sternum are raised by contraction of intercostals muscles.
- Diaphragm contracts and lowers becoming flat.
- Volume of thoracic cavity increases.
- Pressure in thoracic cavity decrease.
- Air is sucked into lungs to equalize the pressure
Exhalation.
- Ribs and sternum lowered by relaxation of intercostals muscles and gravity.
- Diaphragm relaxes and returns to normal dome shape position.
- Volume of thoracic cavity decrease. - Pressure in thoracic cavity increases - Air is forced out of the lungs, to equalize the pressure.
f) Once air rich in oxygen enters alveolus, oxygen diffuses into blood capillaries while carbon dioxide diffuses from blood and enters alveolus space and is exhaled out.
Q. a) Explain why it is health to breathe through nose and not mouth
Why is not advisable to sleep in a poorly ventilated room with charcoal burning?
Mention factors that affect breathing rate
A. a) It is health to breathe through nose because
The rose have hair which traps dust
It have blood vessel which warms the air
b) Sleeping in poorly ventilated room with charcoal burning will lead to poisoning by
carbon monoxide. The carbon monoxide combine with hemoglobin which forms a stable compound called carboxyhaemoglobin. This is a stable compound which do not breakdown. Thus space for carriage of oxygen is this inhibited.
c) Breathing rate is affected by
- Blood carbon dioxide concentration. High concentration of carbon dioxide increases the breathing rate so that excess carbon dioxide can be removed.
Hemoglobin concentration — in anemic condition concentration of hemoglobin is low, making oxygen in body low. The breathing rate increase in an attempt to meet the bodys demand for oxygen.
Q. a) Mention three areas where gaseous exchange take place in plants.
Explain the adaptation of internal part of leaf to the process of gaseous exchange.
What do you understand by
i) Lenticells ii) Pnuematophores
A. a) Gaseous exchange occurs in stomata, lenticels and in cuticle.
b) Internal surface of leaf is moist to dissolve gases has air spaces for circulation of gases.
- It is thin and easily permeable to carbon dioxide and water.
Lenticels are areas in a stem with loosely packed cork cells to allow exchange of gases.
Pneumatophores — are also called breathing roots. They are found on water logged
Soil and help in gaseous exchange.
Q. a) Give the fate of end products of digestion.
b) Give importance of process of respiration
c) Differentiate between respiration and digestion
d) Why is energy produced during respiration stored in form of ATP?
e) Mention two forms of respiration.
f) Write an equation to show aerobic respiration.
g) Describe what happen during aerobic respiration?
h) Mention factors effecting rate of respiration.
A. a) After digestion some food is used to provide energy through respiration and some is converted into compounds which can be stored in the body.
Importance of respiration.
Respiration provides energy which is used for.
Carrying out various activities e.g. Doing work
Provision of heat to maintain temperature.
Maintains metabolic rate.
Respiration is the breakdown of food chemically to release energy. While digestion is the mechanical and chemical breakdown of food into small absorbable particles.
Energy produced in respiration is stored in form of ATP- Adenosine Triphosphate mainly because in this form the energy is inactive form and cannot harm body tissue
Respiration can be aerobic or anaerobic; aerobic respiration occurs in presence of oxygen While anaerobic respiration occurs in absence of oxygen.
Equation for aerobic respiration;
C6H12O6→6CO2 + 6H2O +38ATP + Heat
Aerobic respiration occurs in three stages, the first stage is glycolysis which involves a series of reaction which convert two molecules of three carbon acid called pyruvic acid it occurs whether oxygen is present or not. If oxygen is available pyruvic acid enter krebs cycle. Which is a series of reactions that removes carbon dioxide and hydrogen atoms from pyruvic acid. The hydrogen is involved with electron transport chain in which at end of chain oxygen combine with hydrogen to form water.
Scientist- biochemist Hans Krebs discovered the krebs cycle. He found out that a glucose molecule is broken into pyruvic acid, which joins into chains of chemical reactions producing energy.
Factors affect rate of aerobic respiration include, temperature activity, body size and age among others.
Q. a) Give a reason why anaerobic respiration is also called alcohol fermentation.
Writer equations for anaerobic respiration in animal and plants.
i) Define oxygen debt
ii) Why do a person pant after a vigorous exercise?
iv) Give effects of lactic acid accumulation in muscles.
Differentiate between aerobic and anaerobic respiration.
Mention common infections and disease of respiratory system.
A. a) Anaerobic respiration is sometimes called alcohol fermentation because under a condition without oxygen yeast and plant cells reduce pyruvic acid into alcohol.
b) In plants
C6H1206 →2C2H50H+ 2CO2 + 2ATP
In animals
C6H1206 → 2C3H603 + 2ATP
i) Oxygen debt — this is the amount of oxygen required to get rid of lactic acid which accumulate in body muscles during anaerobic respiration.
ii) A person pants after vigorous exercise because he/she is trying to get in as much oxygen as possible to oxidize lactic acid in muscles.
iii)-Causes muscles crambs
Can cause poisoning of body tissues.
Aerobic respiration
Anaerobic respiration
Occur in oxygen
38 ATP produced
End product are CO2 water and energy


Occur in mitochondrion
Occur in absent of oxygen
2 ATP produce
End products are lactic acid in animal and alcohol in plants
Occur in cytoplasm
e) Main disorders of respiratory system are; pneumonia, tuberculosis, bronchitis,and coughs.
ESSAY QUESTIONS.
Discuss the characteristics of gaseous exchange surface.
Explain mechanism of gaseous exchange in i) Insects ii) Fish iii) Frog
Discuss mechanism of inhalation and exhalation
Discuss how gaseous exchange occurs at alveolus
Discuss the factors that affect the rate of respiration?
g) What are economic importance of alcohol fermentation?