Biology Best Topical Questions and Answers {All Topics in Form one to Four}

May 9, 2024

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in Teachers’ Resources

BIOLOGY TOPICAL ASSIGNMENTS AND ANSWERS

Classification I &II
Name two classes of phylum arthropoda with cephalothorax.
List any three distinguishing features of class mammalia.
Give two characteristics that distinguish scientific names of organisms from the ordinary

names

(a) In which kingdom do bacteria belong?

(b) Give any two benefits of bacteria to man

Name the phylum whose members possess notochord
The diagram below represents a bread mould:-

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(a) Identify the kingdom to which the organism belongs:-

Give a reason why no moulting occurs during the adult stages of insects
Name the branch of Biology that deals with the study of animals
State four ways in which some Fungi are beneficial to human
During a class practical form four students came across a plant whose flower floral parts were in

multiples of fours and fives. To which sub-division and class does the plant belong?

A student caught an animal which had the following characteristics:-
- Body divided into two parts
- Simple eyes
- Eight legs
- The animal belongs to the class

The diagram below represents a bread mould.

(a) (i) Name the Kingdom to which bread mould belongs.

(ii) Give two distinguishing characteristics of the Kingdom named in (a)(i) above.

(b) State the function of the part labelled R

(a) What is meant by the term taxonomy?

(b) The scientific name of a rat is Rattus norvegicus

(i) Write the name correctly

(ii) Identify the genus and species names

List three features that distinguish arthropods from other organisms

The cell – structure & functions of organelles
Name the organelles that perform each of the following functions:
a) Digestion and destruction of worn out organelles.
b) Osmoregulation
Explain why the following processes are important during the preparation of temporary

slides :- (a) Staining

(b) Use of a sharp cutting blade

In a class experiment to establish the size of an onion cell, a leaner observed the following on

the microscope field of view.

If the student counted 20 cells across the diameter of this field of view, calculate the size of one

cell in micrometers.

State the functions of the following cell organelles: (a) Nucleolus. (b) Plasma membrane
What is the of nucleus of a cell made up of?
(a) In a laboratory exercise a student observing a drop of pond water under a microscope saw

and drew a spirogyra. If the magnification of the eye-piece was x5 and that of the objective

lens was x100, what was the magnification of the spirogyra?

(b) If the spirogyra has a length of 5cm at the above magnification, calculate the actual length

in micrometers

(a) Identify the organelle shown below:-

(b) How is the organelle you have identified in (a) above suited to its function

Identify the structures of the cells that perform the following functions:- (a) Synthesize ribosomes

(c)Regulate exchange of substances in and out of the nucleus

(a) State the roles of enzyme catalase in living cells

(b) Which factor inactivates enzyme?

The figure below represents a certain cell organelle:-

(a) (i) Identify the cell organelle

(ii) What is the function of the part labelled A

(b) Name the organelles that perform each of the following functions;

(i) Osmoregulation in amoeba

(ii) Carries out digestion and destruction of worn out cell organelles

State three properties of the cell membrane
The diagram below represents a plant cell

(a) Name a carbohydrate which forms part of the structure labelled S

(b) State two functions of the part labelled R

What do you understand by the following terms
a) Anatomy
b) Biochemistry
State the function of the following parts of a cell a) Ribosome
b) Chloroplasts
a) What is the formula for calculating linear magnification of a specimen when using a

hand lens

State the function of the following cell structures:- a) Ribosome ;
b) Centrioles ;
What is the main structural component of:- a) Cell wall
b) Cell membrane
State two characteristics of the kingdom monera which are prokaryotes
The diagram below represents a cell

(a) Name parts labelled X and Y

b) Suggest why the structures labelled X would be more on one side than the other
During a practical class, form fours estimated the field of view to be 3.5mm. Using the low

power objective, they observed spirogyra cells across the same field of view and counted 8cells.

Calculate the size of each cell and give your answer in micrometer

A student caught an animal which had the following characteristics:-

Body divided into two parts
Simple eyes
Eight legs

a) To what class does the animal belong?
b) State two distinctive characteristics of members of the phylum from which the animals in this

question (15) belongs

Distinguish between the following terms :-
a) Magnification and resolution of a microscope
b) Mounting and staining of a specimen
Name the organelle that performs each of the following functions in a cell.

(a) Transport of packaged glycoproteins

(b) Destruction of worn out cell organelles

Why are the following procedures done when preparing sections to be observed under a light

microscope?

(a) Making of thin sections

(b) Using a sharp blade to make the sections

What are the functions of the following parts of a light microscope?

(a) Eye piece lens (b) Condenser

Given that the diameter of the field of view of a light microscope is 2000um. Calculate the

size of a cell in mm if 10 cells occupy the diameter of the field of view

State the importance of the following processes in microscopy:

(a) staining

(b) sectioning

A cell was found to have the following under a light microscope; cell membrane, irregular

in shape, and small vacuoles. Identify the type of the cell above

State the functions of the following organelles;

(a) Lysosomes

(b) Golgi apparatus

Name the class in phylum arthropoda which has the largest number of individuals
State the functions of each of the following parts in a microscope.

(a) The eye piece lens

(b) The objective lens

The figure below represents an electron micrograph of an organelle that is found in many

cells;

(a) Identify the organelle

(b) State the function of the organelle

(d) Give two examples of tissues where you would expect many such organelles in animal body.

Cell Physiology – Osmosis, Diffusion and Active transport
Two equal strips A and B were from a potato whose cell was 30% of sugar. The strip A was placed in a solution of 10% sugar concentration while B was placed in 50% sugar concentration
a) What change was expected in strip A and B
b) Account for the change in strip A
An experiment was set-up as shown below and left for one hour

(a) State the expected result at the end of one hour

(b) Explain the observations made in this experiment

State what would happen in each of the following:-

(a) A plant cell placed in: – (i) Strong salt solution

(ii) Distilled water

State three physiological processes that are involved in movement of substances a cross the cell

membrane

Potato cylinders were weighed and kept in distilled water evernight. They were then

reweighed.

2.5 g 2.4g 2.7g 3.0 g 3.1 g 3.2g

At the beginning of the Experiment. At the end of the experiment

a) Calculate the average mass of a potato cylinders after reweighing. Show your working.
b) Explain why mass of the cylinders hand increased.
The diagrams below show a red blood cell that was subjected to a certain treatment.

a) Account for the shape of the cell at the end of the experiment.
b) Draw a diagram to illustrate how a plant cell would appear if subjected to the same treatment
The diagram below shows the results obtained when red blood cells are placed in different

Solution X

solution:

Solution Y

(a) What name is given to the process that occurs when the cell is placed in solution Y?

(b) Describe the process that would occur in a plant cell when placed in a similar solution as that

of solution X

The figure below shows the results obtained when red blood cells are put in different solutions:-

Placed in

solution

Placed in

solution

(a) What is the name given to the process that occurs when the cell is put into solution B?

(b) Compare the results obtained when the cell is put in solution B to the results that would be

obtained if a plant cell was put in the same solution

Briefly state two adaptation for each of the following cells to their functions

(i) Spermatozoon

(ii) Palisade mesophlly cell

The diagram below represents a cell at a certain stage in meiotic cell division

a) Name the stage at which the cell drawn above represents
b) Give a distinguishing reason for your answer in 21(a) above
c) State any two differences between mitosis and meiosis
What are two differences between tropisms and tactic movement
An experiment was carried out to investigate the effect of different concentrations of sodium

chloride on human red blood cells. Equal amounts of blood were added to equal volumes of the

salt solution but of different concentrations. The results are shown in the table below:

Set -up		Number of red blood cells
	Sodium chloride concentration	At start of experiment	At the end of the experiment
A	0.9%	Normal	No change in number
B	0.3%	Normal	Fewer in number

(a) Account for the results in the set-up

(b) If the experiment was repeated using 1.4% sodium chloride solution, state the expected

results with reference to:

(i) the number of red blood cells

(ii) the appearance of red blood cells if viewed under the microscope

Name support tissues in plants characterized by the following

(i) Cells being turgid

(ii) Cells being thickened by cellulose

(iii) Cells being thickened by lignin

The diagram below illustrates the behaviour of red blood cells when placed into two different

solutions X and Y.

(a) Suggest the nature of solutions X and Y.

(b) Name the process A and B.

Name two plant processes in which diffusion plays an important role
Two fresh potato cylinders of equal length were placed one in distilled water and the other in

concentrated sucrose solution:

(a) Account for the change in length of the cylinder in:

(i) Distilled water

(ii) Sucrose solution

(b) (i) What would be the result in terms of length if a boiled potato was used?

(ii) Explain your answer in(b)(i) Above

The two cells shown below are obtained from two different potato cylinders which were

immersed in tow different solutions P and Q.

a) i) Name the structure labelled A.
ii) State the function of structure B.
b) If eight of cell I were observed across the diameter of the filed of view of 0.5 mm.

Work out the actual diameters of each cell in micrometers.

c) Suggest the identity of the solution Q.
d) Account for the change in cell I above.
e) State any one importance of the physiological process being demonstrated above in animals.
An experiment shown below was set-up to investigate a certain physiological process

in plants:-

(a) What process was being investigated?

(b) Give the role of the oil layer in this experiment

two hours?

(ii) Explain the observation in (c)(i) above

(d) What effect will the following have on the observation made?:-

(i) Fanning the shoot

(ii) Removing all the leaves from the shoot

(iii) Placing the set-up in the dark

(e) Suggest a suitable control for this experiment

Study the following food web and answer questions that follow:

(a) (i) Name the organisms that occupy the second trophic level

(ii) What is the other name for the second trophic level

(b) Write down two food chains from the food web that:

(i) End with hawks as tertiary consumer

(ii) End with hawks as quaternary consumer

(i) the organism with largest biomass

(ii) the organism with least biomass

Nutrition in (a) plants (b) animals

The chemical equation below represents a physiological process that takes place in living

organisms:

C₆H₁₂O₆ + C₆H₁₂O₆ C₁₂H₂₂O₁₁ + Q

(a) Name the process R

(b) Name the substance Q

The diagram below shows cells in plants:-

(a) Identify the cells shown above

(b) Explain how the cells are adapted to their function

of structure A

(a) A leaf of a potted plant kept in darkness for 48hours was smeared with Vaseline jelly then

exposed to sunlight for 8hours. Explain why the test for starch in the leaf was negative

(b) Name two other processes that were interfered with in the plant

List two functional differences between plants and animals.
Explain how the guard cells are adapted to perform their function.

The diagram below shows chemical reactions A and B which are controlled by enzymes x and y

respectively.

(a) Name: (i) Reaction A.

(ii) Enzyme y

What are the two functions of bile salts during the process of digestion?
State three adaptations of aquatic plants to photosynthesis
A biological washing detergent contains enzymes which remove stains like mucus and oils

from clothes which are soaked in water with the detergent:-

(a) Name two groups of enzymes that are present in detergent

(b) Explain why stains would be removed faster with the detergent in water at 35^oC rather

than at 15^oC

Name the diseases caused by deficiency of : (a) Iodine

(b) Vitamin C

Name two enzymes and one metal ion that are needed in the blood clotting process
The diagram below shows how food boles move along the human oesophogus and the

Intestine

(a) Identify the process illustrated in the diagram

(b) Briefly state how the movement of food boles from position 1 to position 2 is achieved

(b) above

State two adaptations of herbivores which enable them to digest cellulose
State two factors that affect the rate of osmosis
A certain organ K was surgically removed from a rat, later drastic increase in glucose level in the

blood was reported but when substance Q was injected into the animal the whole process was

reversed.

Identify: (i) Organ K

(ii) Substance Q

a) Name the component of a persons diet that is essential for peristalisis
b) Give two groups of food which are reabsorbed along the mammalion digestive system

without undergoing digestion

State three roles of light in photosynthesis
State two ways in which the guard cells differ their adjacent epidermal cells
One of the components of bile is a chemical left over from destruction of red blood cells
i) Identify the chemical substance
ii) What is the role of bile in digestion
(a) What is peristalsis?

(b) Explain how the process above is brought about.

The following reaction may occur in a forward and backward direction.

Water + Carbon (IV) Oxide Glucose + Oxygen + Energy

Name the organelle where the reaction occurs in:

(i) Forward direction

(ii) Backward direction

(b) Give one difference and one similarity for the two organelles named in (a) above

A solution of sugar cane was boiled with hydrochloric acid and sodium hydrogen carbonate was

added to the solution, which was then boiled with benedicts solution. An orange precipitate was

formed.

(a) Why was the solution boiled with hydrochloric acid and then sodium hydrogen carbonate

added in it

(b) To which class of carbohydrates does sugar cane belong?

(i) Transported in animals

(ii) Transported in plants

The diagram below is of a certain type of neurons

(a) Identify the type of neuron

(b) Give a reason for your answer in (a) above

a) The mitochondria organelle has cristae structure on the inner membrane. State the function of

the cristae

b) The diagram below represents a cell organelle

i) Name the part labeled Y
ii) State the function of the part labeled X
a) State the role of emulsification in the digestion of fats in the alimentary canal
b) What is the function of hydrochloric acid in the alimentary canal
Briefly explain the effect of poisoning the roots hair on the uptake of nitrate by plants
Briefly explain the symbiotic relationship in the root nodule of a leguminous plant
Explain how saliva is important in digestion
What is the fate of excess glucose in plants?
State two ways in which guard cells differ from other epidermal cells
Briefly explain the fate of the following products from the light stage of the process of

Photosynthesis: (a) Oxygen (b) Hydrogen (c) ATP

In an experiment to investigate on aspect of digestion, two test tubes A and B were set-up as

shown in the diagram below;

The test tubes were left in the bath for 30minutes.The content of each test tube was then tested for

starch using iodine solution:-

(a) What was the aim of the experiment?

(b) What results were expected in test-tube A and B

Below is a process that takes place along the mammalian digestive system:

(a) Name the processes represented by A and B

(b) Name part of the alimentary canal where the process B takes place

The diagram below represents a cell organelle

(i) Name the part labeled y

(ii) State the function of the part labeled X

(ii) State the function of the vitamin named in (i) above

(a) Name the disease caused by schistosoma parasites in man.

(b) How is schistosome adapted to its parasitic mode of life?

The table below shows three enzymes A, B and C and their respective optimum pH.

Enzyme	Optimum pH
A	6.8
B	2.0
C	8.0

(a) (i) Name the most likely region of the alimentary canal of a mammal where enzyme

B would be found.

(ii) Give a reason for your answer in (a) (i) above

In an experiment to investigate an aspect of digestion, two tubes A and B were set up as shown

in the diagram below.

The test tubes were left in the water bath for 30 minutes. The content of each tube was then tested

for starch using iodine solution.

(a) What was the aim of the experiment?

(b) Explain the expected in the tube.

(a) Name the specific part of the chloroplast where the following processes occur.

(i) Carbon IV oxide fixation

(ii) Photolysis

(b) State one way in which the dark reactions of photosynthesis depends on light reaction.

The concentration of carbon IV oxide in a tropical forest was measured during the course of 24

hour period from mid-night. The graph below shows the results obtained.

Account for the results obtained at: (i) Midnight. (ii) At 12.00 noon.

State three ways by which the rate of enzyme controlled reactions can be increased.
Study the dental formula given below:

I 0; C 0 ; PM 3; M 2

4 0 3 3

(a) Identify with reasons the mode of feeding of the animals whose dental formula is

given above

(b) Calculate the total number of teeth in the mouth of the above animal

Explain why small mammals such as moles feed more frequently than larger ones such

as elephants

State three ways by which plants compensate for lack of the ability to move from one place

to another

Study the diagram below and answer the questions that follow

(a) Label the parts A and B

(b) State one observable difference between the structure above and the liverwort

What is glycolysis?
(a) State two difference between monosaccharide and polysaccharides

(b) Name the bond found in proteins

Name two products of light reaction used in the dark reaction
State two functions of the large intestine in humans.
The diagram below shows a leaf of a growing plant partly covered with aluminium foil.

The plant was placed in the sun from morning to midday and then tested for starch.

(a) What was the aim of the experiment?

(b) State the observation made when the leaf was tested for starch

The figure shows the effect of temperature on an enzyme catalyzed reaction.

(a) Explain what happens between A and B

(b) What is X?

Name two mineral elements that are necessary in the synthesis of chlorophyll.

The figure below is a diagram of the anterior portion of the tapeworm. Taenia solium.

(a) Name the parts labeled A, B, and C

(b) What is the intermediate host of Taenia Solium?

The diagram below represents a longitudinal section through the ileum wall

a) Identify the structure labeled A and B
b) State one function of A and B
c) State two functions of the ileum
d) Explain the role of the liver in digestion
e) State the endocrine role of the pancreas in a mammal
The chart below shows the relationship between concentration of CO₂ around the plant and the

rate of photosynthesis

(a) Account for the rate of photosynthesis between D-E

(b) Account for the rate of photosynthesis between F-G

The diagram below shows the effect of varying light intensity on the exchange of carbon IV

oxide between the leaves of a green plant and the atmosphere.

Light Intensity

a) What is the name given to the point marked x?
b) i) With reference to carbon IV oxide exchange state what happens at point x.
ii) Explain how the effect observed at point x occurs.
c) Explain why there is a net uptake of carbon IV oxide at light intensity above x.
d) What would happen to the plant if light intensity falling on it were maintained at x

throughout?

e) What can you say about the exchange of oxygen between the plant and the surrounding air at

intensities below x?

The following diagram of a leaf shows what happens in a pant leaf during photosynthesis:-

(a) Give two ways in which leaves are adapted to absorb light

(b) Name the gases labelled X and Y

(d) Explain why it’s an advantage for the plant to store carbohydrates as starch rather than as

sugars

(a) What is meant by digestion?

(b) Describe how mammalian small intestine is adapted to its function

Form one students from Inungo school arranged their apparatus as shown below, to investigate a

certain phenomenon. The set up was placed in light.

(a) State the likely aim of the set up

(b) State the role of the syringe in the set-up above

. (c) (i) Name gas X

(ii) Write an equation to show how gas X was formed in the set-up

(d) State three factors that increase the rate of enzyme activity

(e) Give a reason why the test tube is immersed in a beaker of water

A student was culturing E. coli (a bacterium) in a Petri-dish. He placed the Petri-dish in an

incubator at 30^oC.He removed it from the incubator the following day and found that five

colonies of bacteria had grown. He decided to return it into the incubator to give it more time.

When he removed it fourteen days later, he could not observe any colony.

a) Why was there no colony on the fourteenth day?
b) Explain how bacteria cause spoilage of stored food in warm moist conditions.
c) Name other organisms which also cause food spoilage.
d) State their economic importance to nature.
The table below shows the results of an experiment carried out to determine the rate of photosynthesis at different light intensities and varying Carbon (IV) oxide concentrations. The rate was determined by counting the number of bubbles per minute. The temperature was kept constant

Light intensity in lux	% carbon(IV)oxide concentration
	0.0%	0.3%	0.6%	0.9%	1.2%	1.5%	1.8%
1500	0	16	30	38	40	40	40
6000	0	52	80	96	100	98	100
10000	0	80	100	115	120	122	120

a) On a graph paper provided, draw a graph for each of the light intensities. All the three graphs

should be plotted on the same axis (rate of photosynthesis on vertical axis and carbon (IV)

oxide concentration on horizontal axis b) What is the effect of an increase in carbon (IV) oxide concentrations and light intensities

c) Briefly explain how aquatic green plants meet light intensities and carbon (IV) oxide

requirement

d) Using the data provided in the table state two factors required by the green plants for food

production

Explain how the mammalian intestines are adapted to perform their function.
A healthy plant was kept in the dark for 24hours following which two of its leaves were enclosed

in glass flasks as shown below. The set up was the exposed to sunlight for a number of hours.

(a) Why was it necessary to keep the plant in the dark for 24 hours?

(b) Give the function of each of the following in the experiment

(i) Sodium hydroxide

(ii) Sodium hydrogen corbonate

(i) M when tested for starch

(ii) N when tested for starch?

(d) Suggest a suitable control for this experiment

The diagram below shows an experiment that was carried out to measure how fast a were

plant such as Elodea photosynthesizes

The shoot was exposed to different light intensities and the rate of photosynthesis estimated by counting the number of bubbles of gas leaving the shoot in a given time. the results are given below;

Number of bubbles per minute	7	14	20	24	26	27	27	27
Light intensity (Arbitrary units)	1	2	3	4	5	6	7	8

a) Plot these data on apiece of graph paper provided
b) At what light intensity did the shoot produce ;
i) 18 bubbles per minute
ii) 25 bubbles per minute
c) Give two better ways of measuring the rate of photosynthesis than counting bubbles
d) What is the role of light intensity in photosynthesis
e) Account for the expected results of doing this experience at the following temperature;
i) 4ºC
ii) 34ºC

iii) 60ºC

f) Other than light intensity and temperature, name other factors that affect the rate of

photosynthesis

In an experiment, a leaf from a plant which had been kept in the dark overnight was boiled in water for a minute. It was then boiled in alcohol and washed in warm water. Iodine solution was then added onto the leaf:

(a) Why was the loaf boiled in;- (i) Water

(ii) alcohol

(b) (i) What observation was made on the leaf after adding iodine solution

(ii) Give a reason for your answer in (b) above

(d) Why was it necessary to wash the leaf in warm water

(e) What is a variegated leaf?

(f) Write a word equation for the process of photosynthesis

Transport in (a) plants (b) animals
Explain why a fresh wound on the skin bleeds more on a hot sunny day than on a cold

chilly day

State three adaptations of red blood cells to their functions.
How are sieve tube elements adapted to their function
Name the polysaccharides found in the following structures:- (a) Exoskeleton

(b) Xylem vessels

State three factors that maintain transpiration stream
(a) List three forces that facilitate the transport of water and mineral salts up the stem.

(b) Name the tissue that is removed when the bark of a dicotyledonous plant is ringed.

Study the dental formula of an organism below..

I ³/₃, C ¹/₁, Pm ^3/₂, M ¹/₁ = x

(a) (i) What is the total number of teeth this organism possess?

(ii) What is the mode of feeding of the organism?

(b) State two functions of mucus produced along the alimentary canal.

The diagram below shows a bone obtained from a mammal.

(a) Name the part of the skeleton from which the bone has been taken.

(b) Label the parts B and C.

What is the destination of materials translocated in plants.
A person whose blood group is AB requires a blood transfusion, name the blood groups of the

donors.

Explain why capillaries are: (i) Thin walled (ii) Branched
An experiment was set-up as shown below to investigate a certain plant process:

(a) What process was being investigated above?

(b) What observation was made if;

(i) The experiment was left in strong wind for one hour?

(ii) All the leaves were removed from the plant?

How is aerenchyma tissue adapted to its function
(a) State three structural differences between arteries and veins in mammals

(b) Name a disease that causes thickening and hardening of arteries

Identify two forces that help in upward movement of water in plants
State three ways in which red blood cells are adapted to their functions
(a) Distinguish between tissue fluid and lymph

(b) Explain why deficiency of vitamin K leads to excessive bleeding even from small cuts

Name the type of circulatory system found in the phylum Arthropoda
Name the blood vessel that nourishes the heart
a) In which form is oxygen transported in the blood.
b) Why do plants not take in oxygen during the day although they need it for respiration
Name a disease of the blood characterized by excessive production of white blood cells
Laboratory analysis of a patient’s urine revealed the following concentration of various

substances:

Blood proteins 0.00%

Water 50%

Glucose 48%

Salts 0.8%

Urea 1.2%

a) From the analysis above, which disease is the patient suffering from
b) Name two symptoms of the disease in 3(a) above
The diagrams below show two conducting elements of the xylem tissue

a) Identify each of them A and B
b) What makes the cellulose side walls of both A and B able to prevent collapsing?
Explain why the rate of transpiration is reduced when humidity is high
(a) State two functions of the xylem vessels,

(b) List two structural adaptations that make xylem vessels suitable to their function

(a) What is peristalsis?

(b) Explain how the process above is brought about.

The diagram below shows a part of a circulatory system. The arrows indicate the direction of the

flow of blood;

(a) Identify the blood vessels labeled A and B

(b) Explain why it is important to transport food substances to organ C before being released

for circulation to the rest of the body

Name four methods plants employ to remove excretory waste products
a) State the form in which oxygen is transported in the mammalian blood
b) Why is it dangerous to sleep in an enclosed room with a burning jiko
c) Why do plants not take in oxygen during the day although they need it for respiration
Name a disease of blood characterized by excessive – production of white blood cells
The table below is a representation of a chromosomal mutation

Before mutation	L	M	N	O	P	Q
After mutation	L	O	N	M	P	Q

(a) Name the type of chromosomal mutation represented above

(b) Name one mutagenic agent

The diagram shows a section through a plant organ.

(a) (i) Name the class of the plant from which the section was obtained belong.

(ii) Give a reason for your answer in (a)(i) above

(b) How is the part labelled C adapted to its functions?

State two roles of transpiration to a plant
Uptake of water by plants is not affected by metabolic poisons. Explain.
The diagram below represents a plant tissue.

(a) Identify each of them.

(b) What property makes B to be more efficient in function?

A woman gave birth to a child of blood group B+ (B positive). Name the two antigens that

determined her child’s blood group.

A transfusion of RH⁺ blood was given to a patient with Rh^– blood. After one week a similar

transfusion was given to the same patient. What was likely to be the effect of the second

transfusion?

The diagrams below show stages in the process of feeding shown by amoeba.

(a) Name the part labeled A.

(b) Name the process illustrated in the diagram above.

(d) Name the type of cell in human beings that exhibit this process.

(a) Why are xylem vessels more efficient in the transport of water than tracheids?

(b) What is the significance of xylem vessels being dead?

Distinguish between guttation and transpiration
Other than transport, state one other function of xylem tissue in plants
State two functions of aerenchyma tissue in plants
(a) What is sickle-cell anaemia?

(b) Identify the part of the heart that initiates the heart beat

(a) Give a reason why the left ventricle muscles are thicker than the right ventricles muscles

(b) State the forms in which carbon (IV) oxide is transported in the blood

Explain how the following adaptation reduce transpiration in xerophytes

(a) Sunken stomata

(b) Thick waxy cuticle

Name the: (a) Material that strengthens xylem tissue

(b) Tissue that is removed when the bark of a dicotyledonous plant is ringed

The diagram below shows the traverse section of a young stem.

(a) What are the functions of the structures labeled A, B and C

(b) What type of cells are fonjd in the parts labeleld D

Name the components of blood that do not enter the renal tubule in mammals

49 Outline the route taken by a molecule of glucose from the ileum up to the kidney.

The flow chart below shows a blood transfusion pathway

(a) What three conclusions can you draw from the flow chart?

(b) State two precautions that must be observed during blood transfusion

The figure below represents a diagram of a photometer;

(a) What is the photometer used for ?

(b) State the precautions which should be taken when setting up a photometer

conditions;

(i) Dark room

(ii) Leafy shoot enclosed in polythene bag

(iii) In a current of air created by a fan

The amount of blood flow through various parts of the body of a mammal was measured in

cm³ per minute at rest and during different physical activities. Results are shown below.

	Blood flow in cm³/min
	At rest	During light Exercise	During strenuous Exercise
Heart muscles	200	300	1050
Gut	1300	1000	400
Skeletal muscles	1100	5050	23000
Kidneys	900	650	250
Skin	400	1300	600

a) Calculate the percentage change in blood flow through the skeletal muscles and gut when the

mammal was exposed to strenuous exercise.

i) Skeletal muscles
ii) Gut
b) Account for the differences in amount of blood flow through the gut and skeletal muscles;
i) At rest
ii) During streneous exercise
c) Account for the result obtained for the skin during light exercise
d) Name two substances which are removed from the body by the kidney
The diagram below represents a transverse section of a young stem.

(a) Name the parts labeled A, B and D

(b) State the functions of the parts labeled C and E

the root of the same plant

Describe the functions of the various components of the mammalian blood

Gaseous exchange in (a) plants (b animals
a) Name the site of gaseous exchange during breathing in mammals.
b) State three characteristics of the site named in (a)
Why would carboxyhaemoglobin lead to death?
State two causes of coronary thrombosis
What adaptation do red blood cells have for transportation of carbon (IV) oxide?
(a) What is Respiration Quotient (RQ)?

(b) (i) Calculate the RQ of the food substance shown by the equation below.

2C₅₁H₉₈O₆ +145 O₂ 102CO₂ + 98H₂O + Energy

(ii) Name the food substance being oxidized in b (i) above.

Outline three ways in which the gills of Tilapia fish are modified to perform their function.
Identify the surfaces of gaseous exchange in the following:-

(i) Paramecium;

(ii) Roots;

(iii) Frog;

(a) Name two gaseous exchange

(b) Explain how oxygen gets into the haemolymph of an insect

(a) Outline two physiological changes that occur in the body to lower the level of Carbon (IV)

Oxide after vigorous physical exercise

(b) Name the site of respiration in a cell

What is the importance of counter current flow in the exchange of gases in a fish
State four ways in which red blood cells (RBC) are adapted to the their function
(a) (i) Where in a cell does glycolysis take place?

(ii) Name the product of the above process

(b) Briefly explain Kreb’s cycle in a plant cell during anaerobic respiration

Describe the changes that occur to the rib cage and the diaphragm during inspiration
a) What is translocation b) Name two forces that maintain transpiration stream
Most carbon (IV) oxide is transported form tissues to the lungs within the red blood cells and

not in the blood plasma. Give two advantages of this mode of transport

Give a reason why halophytes have pneumatophores
Give two characteristics of respiratory surfaces in animals
Give a reason for each of the following on mammalian Red blood cells

(a) Absence of the nucleus

(b) Biconcave shape

State two ways in which bodies of people living in high altitude areas respond to low oxygen

concentration.

Explain what would happen to a mammalian Red blood cell 30 minutes alter being placed in

distilled water.

(a) State two ways in which the surface area of the fish filaments is increased for efficient gaseous

exchange.

(b) What is the importance of counter flow system in the filaments of a fish.

The apparatus below illustrates breathing in mammal.

Describe what happens if the rubber plug is pulled in the direction shown by the arrow.

Describe the path taken by oxygen gas from atmosphere to the tissues of an insect.
Why should respiratory surfaces be: (i) Moist (ii) Thin
The set up below represents an experiment to investigate the process of photosynthesis.

The set up placed in sunlight for six hours.

(a) Why was sodium hydrogen carbonate added to water in this experiment?

(b) Explain why the number of bubbles reduced by evening

(d) Explain why the water was used in this experiment

(a) State two adaptations of red blood cell to its functions

(b) Name two ways in which carbon (IV) Oxide is transported in mammalian blood

The diagram below represents an organ from a bony fish. Study the diagram and answer the

questions that follow:

(a) State the functions of each of the following:

(b) How is the structure labeled C adapted to its function?

State how the tracheal system in insects is adapted for gaseous exchange.
Differentiate between active immunity and passive immunity
Name three sites where gaseous exchange takes place in terrestrial plants.
An athlete training to take part in an international competition moved to a high attitude area where

he was to train for twelve days before the competition. He took his pulses per minute daily and

tabulated them as shown below:-

a) Other than pulse rate, name one other process which was affected by change of altitude
b) Account for the change in pulse rate from:- i) Day 1 to day 7
ii) Day 8 to day 12
c) Explain the advantage this athlete has over the one who trains in a lower altitude area
d) The equation below represents a reaction which takes place during rapid muscular movements

in humans.

Glucose Lactic acid + 150KJ

i) State two effects of this reaction to an individual
ii) How is lactic acid finally eliminated from the muscle tissues of the human after the muscle
a) State any two structures used for gaseous exchange in plants.
b) Name any two sites where gaseous exchange takes place in a leaf of a terrestrial plant.
c) State any two types of leaves and their respective functions.
d) Briefly describe how stoma opens.
The diagram below represents a section of the human respiratory system:

(a) One can inhale through path A, or B. Giving reasons, state the more appropriate path.

(b) How is the part labbelled C adapted for its function?

(a) How is the structure of mammalian gaseous exchange system adapted to its functions

(b) Describe the mechanism of opening and closing of the stomata using the photosynthetic

theory

(a) Describe the mechanism of inhalation in man.

(b) Using photosynthetic theory explain the mechanism of opening of stomata.

In an experiment to investigate a certain processes in a given plant species, the rate of carbon (IV)

oxide consumed and released were measured over a period of time of the day. The results of the

investigation are shown in the table below:

Time of the day (hours)	6	8	10	12	14	16	18	20	22	24
Carbon (IV) oxide consumed in mm³/min	10	43	69	91	91	50	18	0	0	0
Carbon (IV) oxide released in mm³/min	38	22	10	3	3	6	31	48	48	48

b) Name the biochemical processes represented by;

(i) Carbon (IV) oxide consumption

(ii) carbon (IV)oxide release

(i) 6-16 hours

(ii) 20-24 hours

(d) Account for carbon (IV) oxide released between 12-16 hours

(e) (i) What is compensation point?

(ii) From the graph state the time of the day when the plant attains compensation point

(f) Explain how high temperature above optimum affects the rate of carbon (IV) oxide

consumption in the plant.

Respiration
(a) Distinguish between gaseous exchange and respiration

(b) Name the products of anaerobic respiration in plants

(a) State two phases of aerobic respiration

(b) With a reason, state the phase that yields more energy

A process that occurs implants is represented by the equation below:-

C₆H₁₆O₆ 2C₂H₅OH + 2CO₂ + Energy

(Glucose) (Ethanol) (Carbon (IV) Oxide)

(a) Name the process

(b) State the economic importance of the process named in (a) above

Give a reason why it is difficult to calculate respiratory quotient (RQ) in plants
a) Explain what is meant by the term oxygen debt in human beings
b) What are the end products of anaerobic respiration in animals
The apparatus below was set up by a student to find out the changes in gases during

germination

a) After 48 hours the level of water in the U-tube at A and B was as shown. Explain the

observation

b) Calculate the respiration quotient (RQ) from the equation below:-

2C₅₁H₉₈O₆+145O₂ 102 CO₂ + 98H₂O + Energy

c) Identify the substrate being respired in the above equation
One molecule of lipid gives more energy than one molecule of glucose when respired aerobically

but it is NOT always used as a respiratory substrate

a) Give two reasons for this
b) Name two disaccharides which are reducing sugar
(a) (i) Where in a cell does glycolysis take place?

(ii) Name the product of the above process

(b) Briefly explain Kreb’s cycle in a plant cell during anaerobic respiration

How is the mammalian skin adapted to its protective function?
The oxidation state of a certain food is represented below by a chemical equation:-

2 C₃H₂O₂N + 6O₂ (NH)₂CO₂ + 5CO₂ +5H₂O

a) Calculate the respiratory quotients (RQ) of the food substrate
b) Identify the food substrate
Whooping cough is a disease of the respiratory system name the causative agents and give two

symptoms

How does the sunkness of stomata help in minimizing the rate of transpiration in plants
State two roles of adrenaline in man
Explain why a rat, though small eats more frequently than an elephant
Active yeast cells were added to dilute sugar solution in a container. The mixture was kept in a

warm room. After a few hours bubbles of a gas were observed escaping from the mixture

(a) Write an equation to represent the chemical reaction above

(b) State two economic importance of this type of chemical reaction in industry?

(a) Give two reasons why fats are not the main respiratory substrates in the body of a mammal

and yet they give a lot of energy when oxidized.

The equation below summarizes a metabolic process in plants.

Glucose Ethanol + carbon (IV) oxide+ Energy

State two industrial applications of the above equation.

(a) Differentiate between respiration and respiratory surface.

(b) Why is an effective respiratory system often associated with a circulatory system.

State two reasons why lipids are rarely used as a respiratory substrate compound to

carbohydrates.

The equation below shows respiration for a certain food substrate. Study it and answer questions

that follow:

2C₅₁H₉₈O₆ + 145O₂ 102CO₂ + 98H₂O

(a) Calculate the respiratory Quotient, RQ

(b) Suggest with reasons the possible food substrate

The apparatus below was used to investigate anaerobic respiration:-

(a) How would you remove dissolved oxygen from the glucose before the experiment

commencing?

(b) State what happens to the lime water as the experiment proceeds to the end

(d) Explain what would happen if the temperature of glucose solution and yeast was raised

beyond 45^oC?

Excretion and homeostasis
Explain the following:- i) Fresh water fish excrete ammonia
ii) Glucose is absent in urine yet present in glomerular filtrate
(a) State two functions of the kidney

(b) Name two substances that are not found in urine of a healthy person

(a) State two structural modification of the kidneys of deserts animals like kangaroo rat.

(b) Describe how ingestion of very salty food may reduce the amount of water excreted in urine.

A student mixed a sample of urine from a person with Benedict’s solution and heated, the colour

changed to orange.

(a) What was present in the urine sample?

(b) What did the student conclude on the health status of the person?

(a) If the human pancrease is not functional:-

(i) Name the hormone which will be deficient

(ii) Name the disease the human is likely to suffer from

(b) What is diuresis?

State one structural adaptation of nephron in the kidney of a desert mammal
Name the nitrogenous wastes excreted by the following organisms:-

Animal Nitrogenous Waste

(i) Desert mole

(ii) Marine fish

(iii) Tilapia

The table below shows description of sizes of glomeruli renal tubules of two animals which are

living in different environments

	Animal X	Animal Y
Glomeruli	Large and few	Small and many
Renal tubules	Short	Long

(a) Name the likely environment in which each animal lives : (i)Animal X

(ii) Animal Y

(b) What role does vasoconstriction play in thermoregulation?

The table below shows the approximate percentage concentration of various components in blood

plasma entering the kidney, glomerular filtrate and urine of a healthy human being

Component	Plasma	Glomerular filtrate	Urine
Water	90	90	94
Glucose	0.1	0.10	0.00
Amino acids	0.05	0.05	0.00
Plasma proteins	8.0	0.00	0.00
Urea	0.03	0.03	2.00
Inorganic ions	0.72	0.72	1.50

(a) Name the process responsible for the formation of glomerular filtrate

(b) What process is responsible for the absence of glucose and amino acids in urine?

What is the importance of sebaceous glands in the human skin?
Explain why sweat accumulates on a person’s skin in a hot humid environment
Distinguish between diabetes mellitus and diabetes inspidus
State two processes through which plants excrete their metabolic wastes.
The figure below shows a vertical section through a mammalian kidney.

(a) Label the parts A and B

(b) Which part is the Bowman’s capsule found?

(a) Explain the effects of the production of large amounts of Antidiuretic hormone in the human

body

(b) State two functions of the loop of Henle

Study the homeostatic scheme below:

(a) Identify the hormone labeled A

(b) Name the site of action of hormone A

State three importance of Osmosis in plants
A patient was complaining of thirst most of the times. A sample of the patient’s urine was found

not to contain a lot of sugar but was dilute:-

(a) Name the hormone the person’s body was deficient of

(b) Which gland produces the above hormone

State two features in the nephron that facilitate ultra filtration
The table below shows a description of size of glomeruli and renal tubules of two animals

which are adapted to living in different environment:-

Animal A Animal B

Glomeruli large and few small and many

Renal tubules short long

a) Name the likely environment in which animal A lives b) Suggest the main nitrogenous waste produced by animal B c) Name the organelle of osmoregulation in each of the following animal: i) Paramecium
ii) Insects
What role is played by the liver in excretion?
The equation below represents a metabolic process that occurs in the mammalian liver: Amino acids organic compound + urea
a) Name the process

(b) What is the importance of the process to the mammals?

A person was found to pass out large volume of dilute urine frequently. Name the:-

(a) disease the person was suffering from?

(b) hormone that was deficient

Explain the effects of the following on the quantity and composition of urine

(a) Drinking large amount of clean water

(b) Drinking very salty soup

(a) Distinguish between excretion and egestion

(b) State the importance of excretion in the bodies of living organisms.

The diagram below shows simplified structures of kidneys from two different animals.

Animal N

Animal M

(a) Suggest possible habitat in which animal N is found.

(b) Give two reasons for your answer in (a) above.

(a) What is poikilotherm?

(b) State two classes of phylum chordata where all members are poikilothermic .

The diagram below represents a mammalian nephron

(i) Name the structure labelled Q …………………………………………………………………………

(ii) State two adaptations of part labeled R

Distinguish between internal environment and external environment as used in
The diagram below represents a nephron of a mammal:

(a) Name the parts labeled A, B and D

(b) Name a major substance in glomerular filtrate whose concentration remains the same

between A and C

Name the parts of the flower that are responsible for the production of gametes
The equation below represents a metabolic process that occurs in a certain organ in the m

mammalian body:-

Ammonia enzymes Organic compound Q + water

Carbon (IV) oxide

a) Name the process represented in the equation.
b) Name the organ in which the process occurs.
c) Why is the process important to the mammal?
d) Identify the organic compound
e) Explain the source of ammonia in the organ named in (b) f) What happens to organic compound Q?
Kosgei and Onyancha collided during a football match and each got bruised. Kosgei’s bruise stopped bleeding after ten minutes while Onyancha’s bruise continued bleeding and he had

to be taken to hospital for treatment.

(a) Explain the process which brought about stoppage of Kosgei’s bleeding

(b) Distinguish between blood clotting and haemagglutination.

The table below shows the percentage of some substances in the glomerular filtrate and urine

of a certain mammal:-

Substances	Contents in glomerular filtrate	Contents in urine
Water	90	90
Sodium ions	0.3	0.35
Chloride ions	0.37	0.60
Glucose	0.1	0.0
Urea	0.03	2.0
Proteins	0.0	0.0

(a) From the above table, account for ; (i) The absence of glucose in urine (ii) The absence of protein in both glomerular filtrate and urine

(b) Explain the significance of the flow system in the nephron where the glomerular filtrate

flows in opposite direction to that of blood in the surrounding capillaries

amount of salts Percentage of water

Amount of salts

(d) List any two diseases /disorders of the kidney

Study the diagram below and answer the questions that follow

(a) Name the structure represented by the diagram

(b) (i) Name the parts labelled D and M

(ii) Name the hormones whose sites of action are Q and G (c) Name one substance that is present in part N but absent in part Z

(d) The contents of part V were boiled with Benedicts’ solution and an orange precipitate was

formed. Account for the results

In an investigation, two persons A and B drunk the same amount of glucose solution. Their blood

sugar levels were determined immediately and thereafter at intervals of one hour for the next six

hours.

The results were as shown in the following table:-

Time (hrs)	Blood glucose level (mg/100ml)
	Person A	Person B
0	90	120
1	220	360
2	160	370
3	100	380
4	90	240
5	90	200
6	90	160

(a) Draw a graph of blood sugar levels of persons A and B against time on the same axis

(b) Explain each of the following observations;-

(i) Blood sugar level increased in person A between 0 and 1 hour

(ii) The blood sugar level dropped in person A between 1 and 4 hours

(d) Suggest a reason for the high sugar level in person B

(e) How can the high blood sugar level in person B controlled?

(f) What is the biological significance of maintaining a relatively constant sugar level in a human

being

(g) Account for the decrease in the blood glucose level of person B after 4 hours

An experiment was carried out to determine the effect of drinking on excess amount of water on

the flow of urine. A person drinks one litre of water and urine was collected at intervals of 15minutes.

The results were as shown below:

Time in minutes	0	15	30	45	60	75	90	105	120	135
Urine output ml/min	1.6	1.6	1.6	5.4	9.0	9.0	7.6	3.0	0.8	0.8

(a) Plot a suitable graph to represent urine output with time.

(b) Explain the rate of flow of urine between the following times;

(i) 15 and 60minutes.

(ii) 60 and 75minutes.

(iii) 75 and 135 minutes.

a) Explain how urea is formed in the human body
b) Describe the path taken by urea from the organ where it is formed until it is released from

the human body

The diagram below represents a mammalian nephron.

(a) Name the structures labeled B,C and D

(d) How is the pressure in structure A achieved?

40.

a) Identify substance X

(d) Give three other functions of the liver

The flow diagram below represents blood clotting process

a) Name the proteins represented by the letters; V, Y, Z b) State the importance of blood clotting
c) Why doesn’t the physiological process above occur in undamaged blood vessels
How does an Endotherm respond to both heat gain and heat loss?

The diagram below represents a mammalian nephron

(a) Name the: (i) Structure labelled P

(b) State the structural modifications of the part label led Q for

(i) Desert mammals

(ii) Fresh water mammals

(c ) (i) Name one substance present at point R but absent at point S in a healthy mammal.

(ii) The appearance of the substance you have named in (c)(i) above is a symptom of a

certain disease. Name the disease

Describe how the mammalian skin regulates body temperature

Ecology
A student wanted to estimate the number of grasshoppers in 5km² grass field near the school compound.

Using a sweep net he captured 36 grasshoppers. He used a red felt pen to mark the thorax of each insect before releasing back into the field. Three days later he made another catch of grasshoppers. He collected 45 grasshoppers of which only 4 had been marked with red mark.

a) Name the above method used in the population estimation b) Calculate the population of grasshoppers using the above data
What is the significance of the following in the ecosystem?
a) Decomposers
b) Predators
Birds feed on grasshoppers that feed on grass.
a) Draw a possible food chain from the above information
b) Explain why the biomass of organisms decreases at each preceding trophic level.
Define the following terms:-

(i) Autecology ;

(ii) Biomass;

State two most important factors that favour exponential growth of a population of gazelle

in a park

(a) Distinguish between habitat and niche.

(b) Explain why Biomass of producers is greater than that of primary consumers in a balanced

ecosystem.

pests and parasites

Explain how oil as a pollutant may affect aquatic plants and animals?
The diagram below shows part of a food relationship in an ecosystem:-

(a) Name the food relationship above

(b) How many trophic levels are shown in the diagram above?

Use the food web below to answer the questions that follow:-

(a) Construct a food chain ending with crocodile as a quartenary consumer

(b) Name the organisms in the food web hat has only one predator

50 black mice and 50 white mice were released in an area inhabited by a pair of owls. After

four months, the mice in the area were recaptured and only 38 black mice and only a white mice

remained.

(a) How would you explain these results?

(b) Name the theory of evolution that support the results in (a) above

In a certain school Form three class did an experiment to estimate the number of Tilapia

in their fish pond. 725 tilapia were netted marked and released.

a) State the method used in this exercise
b) Calculate the tilapia population.
c) State two assumptions made by the students during the investigation
An investigation was carried out on a terrestrial ecosystem. The population sizes and species

biomass were determined and recorded as shown in the table

SPECIES	POPULATION SIZE	SPECIES BIOMASS
A	1×10³	1×10³
B	1×10³	1×10^-1
C	1×10⁵	1×10
D	1×10	1×10⁴

If these organisms had a feeding relationship, construct a simple food chain involving all the organisms
Construct pyramid of numbers using the data provided above
State one disadvantage of using pyramid of number in expressing feeding relationships in ecological ecosystem
The figure represents a feeding relationship in an ecosystem

(a) Write down the food chain in which the Guinea Fowls are secondary consumers

(b) What would be the short term effects on the ecosystem if lions invaded the area

Outline three roles of active transport in human body
Distinguish between community and population
Describe how the belt transect can be used in estimating the population of a shrub in a

grass land

A fish farmer wanted to know the number of fish in a pond. He collected 10 fish from the pond

and labeled each, by a tag label on its fin and returned the ten fish to the pond to mix with

other fish . When he later collected 50 fish from the pond, he found only four of them had labels

a) Estimate the total number of fish in the pond (show your workings)
b) What two assumptions are being made in this methods of estimating population
What is the importance of saprophlic fungi and bacteria in an ecosystem
i) Name one main cause of global warming
ii) What are the effects of global warming
Explain how saliva is important in digestion
Give a reason why two species in an ecosystem cannot occupy the same niche
Below is a pyramid of numbers indicating trophic levels:-

(a) What do you understand by the term trophic level?

(b) Name the trophic level numbered 5 on the pyramid

(d)What is the significance of the arrow R

Two populations of the same species of birds were separated over a long period of time by an

ocean. Both populations initially fed on insects only. Later, it was observed that one population

fed entirely on fruits and seeds, although insects were available. Name this type of evolutionary

change

To estimate the population size of crabs in a certain lagoon, traps were laid at random. 400 crabs

were caught, marked and released back into the lagoon. Four days later, traps were laid again and

360 crabs were caught. Out of the 360crabs, 90 were found to have been marked

(i) Calculate the population size of the crabs in the lagoon

(ii) What is the name given to this method of estimating the population size

State the function of each of the following apparatus:

(a) Pooter …

(b) Sweep net …………

State the role of the following apparatus in the study of living things.

(a) Sweep nets.

(b) Pooter.

Name three density dependent factors in an ecosystem.
(a) What are the two main components of an ecosystem?

(b) Apart from mere observation of actual feeding suggest two methods that can be used

to determine the type of food eaten by animals

The chart below represents a simplified nitrogen cycle.

What is represented by X, Y and Z?

In an ecological study, a locust population and that of crows was estimated in a grassland area

over a period of one year. The results were tabulated as shown below.

Months	J	F	M	A	M	J	A	S	O	N	D
No. of Adult locusts x 10²	90	20	11	25	200	652	15	10	35	192	456
Number of crows	4	2	0	1	8	22	2	1	1	5	15
Amount of rainfall	20	0	55	350	520	350	10	25	190	256	350

a) Draw a graph of population of locusts and crows against time
b) i) State the relationship between rainfall and locust population
ii) Account for the relationship you have stated in b (i) above
c) What happens on the populations of locusts and crows in the months of January to March?

Give a reason.

d) If the area of study was one square kilometer, state one method used to estimate the

population of :- i) Locusts

ii) Crows

(e) (i) State the trophic levels of the (i) Locusts and (ii) crows

(ii) Construct a simple complete food chain involving these organisms

(f) If the locust were removed from the food chain, what would be its effect?

(g) Define biomass

Two species of antelopes were introduced into an ecosystem at the same time in equal numbers.

The graphs below show their relative numbers during the first eight years of their co-existence.

Study the graphs carefully and answer the questions that follow.

a) i) Which species of antelope has better survival adaptations.
ii) Give a reason for your answer above.
b) i) Name the type of curves shown.
ii) Name the phases labeled PQ, QR, RS, ST
c) Explain the shape of the curve for the species of Antelope A between
i) Q and R.
ii) S and
d) i) State the type of competition shown by the two species of antelopes.
ii) State any two symptoms of intraspecific competition in plants.
e) Suggest how the species B avoid competitive exclusion..
f) State any three adaptations that enable the antelopes to overcome predation.
g) State any two possible methods by which populations of the two antelopes’ species were

determined.

Explain five abiotic factors that affect the ecosystem
The data shown below was taken from Savannah grassland habitat. Examine it carefully and then

answer the questions that follow:-

(a) Draw three food chains

(b) Draw a pyramid of numbers for a food chain with four trophic levels and indicate the trophic

levels at which each member feeds

(d) Why is it advisable to feed 100kg of grain to man instead of using it to fatten steers then

supply beef to human population?

Organism	Population
Grasses	1000
Caterpillars	500
Squirrels	300
Frogs	200
Gazelles	300
Elephants	100
Snakes	50
Hunting dogs	40
Vultures	40
Lions	40
Hawks	10

Study the following food web and answer questions that follow:

(a) (i) Name the organisms that occupy the second trophic level

(ii) What is the other name for the second trophic level

(b) Write down two food chains from the food web that:

(i) End with hawks as tertiary consumer

(ii) End with hawks as quaternary consumer

(a) Explain how food as a factor regulates the population of animals in an ecosystem

(b) Describe the flow of energy from the sun through the different trophic levels in an ecosystem

(a) Describe how a population of grasshoppers in a given area can be estimated

(b) Describe how the belt transect can be used in estimating the population of a shrub in

a grassland

The flow chart below represents a feeding relationship in an ecosystem

(a) Name; (i) The producers in the ecosystem

(ii) Two organisms which are both secondary and tertiary consumers

(b) State two short term effects of immigration of insects in the ecosystem.

(d) State three disadvantages of using synthetic pesticides over Biological control.

(e) State the role of each of the following in an ecosystem;

(i) Saprophytes

(ii) Leguminous plants

(iii) Explain the role of producers in an ecosystem

(f) Name one method that would be used to estimate the population of small fish in the

ecosystem

How are leaves of mesophytes adapted to their functions?

Reproduction in (a) plants (b) animals
a) Name the part of an ovule that develops into each of the following parts of a seed after

fertilization i) Testa ii) Endosperm

b) What is parthenocarpy?
State three roles of placenta during pregnancy.
Name three main methods through which HIV/AIDS is transmitted
(a) Name the processes that lead to fruit formation without fertilization

(b) Name the hormone that causes leaf, flowers and fruit abscission

State the roles of oviduct in female reproductive system
The diagram below represents a mature embryo sac. Study it carefully and answer the questions

that follow:

(a) Identify structures X and Y

(b) Why is cross pollination more advantageous to a plant species than self pollination?

The diagram below shows a phenomenon which occurs during cell division.

(a) Name the part labeled T.

(b) (i) State the biological importance of the part labelled T.

(ii) Identify the type of cell division in which this phenomenon occurs.

(a) When are the two organisms considered to belong to the same species.

(b) Explain the term alternation of generations.

(a) Explain why Larmack’s Theory of evolution is not accepted by biologists today.

(b) State the significance of mutation in evolution.

(a) Give two roles of the placenta.

(b) Explain why hormone testosterone still exerts its influence even when vas deferens have

been cut.

Name two mechanisms that hinder self fertilization in flowering plants
State three ways in which plants compensate for lack of movement
(a) What do you understand by the term double fertilization?

(b) State two adaptations of animal dispersed fruits

Name the hormone that;

(a) Stimulate the contraction of uterus during birth (b) Stimulates the disintegration of the corpus inteum when fertilization fails to take place

State three ways in which flowers parent self pollination
The diagram below represents a stage in the development of human foetus

(a) State one function of each of the structures labelled A and B

(b) Apart from the size of the foetus what else from the diagram illustrates that birth was going to

occur in the near future

Name the type of placentation where;

(i) Placenta appears as one ridge on the ovary wall

(ii) Placenta appears at the centre of the ovary with ovules on it and the dividing walls of carpels

disappear

The diagram below represents a mature fruit from a dicotyledonous plant, observe it and

answer questions that follow

a) To what group of fruits does the specimen belong?
b) Suggest the possible agent of dispersal of the fruit
Explain why menstrual periods stop immediately after conception?
a) Why is sexual reproduction important in evolution of plants and animals
b) The calyx cells of a certain plant has 22 chromosomes. State the number of chromosomes

present in the plant’s

i) Endosperm
ii) Ovule cell

21. The diagram below shows a pollen – tube entering the ovule of a flowering plant

a) Name the parts labeled A, B and D
b) Name the kind of fertilization exhibited by the above flowering
Donkey and zebra are closely related yet not of the same species. Explain
Name two factors in the environment which organisms respond to
What is meant by the terms:- a) i) Epigynous flower
ii) Staminate flower
b) Name the protective membranes surrounding the brain
The diagram below illustrate a process in a given species of organism

a) Name the organism that undergoes the process above
b) Identify the process shown to be taking place
State two ways by which HIV/AIDS is transmitted from mother to child
(a) State the role of centrioles during cell division

(b) (i) Explain the role of chlorophyll in photosynthesis

(ii) What is the main product of the dark stage of photosynthesis?

(a) At what stage of meiosis is the chiasmata formed?

(b) (i) What is the significance of the above part in living organisms?

(ii) State two importance of meiosis in living organisms?

(a) State two ways in which the male parts of a wind pollinated flower are adapted to

their mode of pollination

(b) Differentiate between monoecious and dioecious plants

(a) What is seed dormancy?

(b) State two ways in which seed dormancy can be broken

(a) Explain two importance of the adult stage in metamorphosis in insects

(b) What is the importance of the juvenile hormone in insects?

Describe the possible effects of discharging hot effluent from a factory into a slow flowing river
State two disadvantages of external fertilization in animals
State three roles of placenta in mammals
(a) The diagram below shows a stage during cell division

(i) Name the stage of cell division

(ii) Give a reason for your answer

(b) Name two structures in plants where male and female gametes are produced

State two advantages of metamorphosis to the life of insects
List four differences between Mitosis and Meiosis
Give a reason why two species in an ecosystem cannot occupy the same niche
State the functions of the following hormones in the menstrual cycle :

(i) oestrogen

(ii) luteinizing hormone (L.H)

(iii) Follicle stimulating hormone (FSH)

The diagrams below represent two gynoecia A and B obtained from two different plants.

(a) What name is given to; Gynoecium A?

Gynoecium B?

(b) State the observable difference between the gnoecia A and B

State the difference between the sperm cell and the ovum.
(a) Name the parts of the flower in which pollen grains area formed.

(b) Name two nuclei found in pollen grains.

The diagram below represents a stage in cell division.

(a) Name the stage of all division shown in the diagram above.

(b) Give reasons for your answer.

Name the hormone that:

(a) Stimulate the contraction of uterus during birth.

(b) Stimulate the disintegration of corpus luteum when fertilization fails to take place.

State three ways in which seed dormancy benefits a plant
(i) State two major structural differences between fruit and a seed

(ii) Why is it advisable to use biological control of pests?

State the functions of the following parts in the male reproductive system

(a) Somniferous tubules

(b) Sertoli cells

(a) Name the parts of a flower responsible for gamete formation

(b) State one feature of pollen grains from a wind pollinated flower

Name the mechanisms that hinder self-fertilization in flowering plants
The eggs of birds are relatively much larger than those of mammals. Explain
Distinguish between the following terms:

Pollination and fertilization

a) Describe the various mechanisms of fruit and seed dispersal.
b) Describe the varying events that follow a flower after fertilization.
Describe how fruits and seeds are suited to their mode of dispersal
The diagram below represents some hormones, their sources and functions in a mammal:

(a) Identify the master gland described above

(b) Name hormones (ii), (iii), (v) and (iv)

(d) Other than stimulating the development of uterine wall, suggest one other function

of hormone (vi)

The diagram below represents some hormones, their sources and functions in mammals.

a) Name the hormones I, II and III
b) Name hormones IV and state its function
c) Name the control labelled A & B
d) Name one secondary sexual characteristic common to both males and females
(a) State the role of spleen in human defense mechanism

(b) State two ways by which the HIV spread may be controlled through patients in hospitals

(d) Why is immunization against diseases encouraged by the government

(e) State how natural active acquired immunity is attained by an individual

Explain how seeds and fruits are adapted to the various methods of dispersal
The diagram below represents female reproductive system;

a) Name the part labeled; A, B, C and D
b) State two functions of structure A
c) How is part C adapted to its function?
d) Of what significance is part E to reproduction?
The diagram below represents a human foetus in a uterus

(a) Name the part labelled S

(b) (i) Name the blood vessels labelled A and B
(ii) State the difference in composition of blood found in vessels A and B

(d) State the role of the part labelled R

An experiment was carried out to investigate the rate of growth of pollen tube against time.

The results are shown in the table below:

Time in minutes	Growth of pollen tube in millimeters
0	0
30	4.0
60	9.8
90	15.2
120	20.0
150	21.6
180	22.4

(a) (i) On the grid provided draw a graph of the pollen tube growth against time.

(b) (i) At what intervals was the growth of the pollen tube measured?

(ii) What was the length of pollen tube at; 130 minutes

(iii) At what time was the length of the pollen tube 18mm?

(iv) With reasons, describe the growth pattern of the pollen tube between:

0 to 120minutes
Reason
120 to 180 minutes
Reason

(v) State the importance of the growth of pollen tube to the plant

Growth and development in (a) plants (b) animals
a) Name the hormone which controls moulting in insects.
b) State the importance of moultng in insects.
The illustration below represents an eye defect

a) Name the eye defect .
b) Name the lenses that can be used to correct the defect.
(a) State two functions of the kidney

(b) Name two substances that are not found in urine of a healthy person

The diagram below represents a growth pattern of arthropods.

Time (days)

(a) Name the type of growth pattern represented on the graph.

(b)Identify the process represented by X.

Distinguish between natural and acquired immunity.
The cells shown below were obtained from different parts of a young root tip:

Give the name of the zone from which each cell was obtained A, B and C

Differentiate between continuous and discontinuous variations
An experiment was set-up as shown in the diagram below:-

(a) Suggest the possible aim of this experiment

(b) Account for the observation at the end of the experiment

State the location of each of the following plant meristematic tissues:-

(i) Vascular cambium

(ii) Intercalary meristem

Define the following terms: a) Growth
b) Development
State two advantages of metamorphosis in the life insects
State one disadvantage of exoskeleton in insects.
Distinguish between primary growth and secondary growth in a flowering plant
What is the role of the following to a germinating seed: (i) Oxygen

(ii) Cotyledons

Give three applications of plant growth hormones in agriculture
State two functions of calcium in the human body
State the biological importance of ecdysis in arthropods
The diagram below represents a stage during the process of germination.

(a) (i) Name the type of germination illustrated in the diagram

(ii) Give a reason for your answer in (a) (i) above.

(b) Give two functions of the part labelled X

In an experiment young potted seedlings were placed in a dark box with unilateral light source

as shown below:

(a) What was the aim of the experiment?

(b) State the observations made on the seedlings after 3 days

The graph below represents the growth of animals in a certain phylum.

(a) Name the type of growth pattern shown on the graph.

(b) Identify the process represents by x.

(a) State the role of the vascular cambium in plant growth and development.

(b) Explain why monocotyledons plants do not undergo secondary thickening.

Explain how placenta is adapted to its functions
State the role of the following during germination:

(a) oxygen

(b) enzyme

Name the type of responses exhibited by:-

(a) (i) Marine crabs burrowing into the sand to avoid dilution of their body fluids

(ii) Chlamy domonas plant moving towards a region of high light intensity

(b) (i)What type of neuron is drawn above?

(ii) Using an arrow, show the direction of the nerve impulse

(iii) Name the part labelled X

(iv) State the function of part labelled Y . (c) Give two differences between reflex action and conditioned reflex action

The experiment set – up below was designed to investigate an aspect of germination.

a) Why was potassium hydroxide pellets used in this experiment?
b) What was the role of moist cotton wool in this experiment?
c) i) By means of an arrow, indicate on the diagram the direction in which red dye would move

during the experiment.

ii) Give reason for your answer in c(i) above.
d) Other than the factor investigated above, state any other one factor necessary for germination

process.

The following data represents the development in dry mass of germinating seedlings within 18

weeks:

Time in weeks	0	1	2	4	6	10	13	15	16	18
Dry mass in grammes	0.1	2	3.2	10	18	32	44	45	44	38

(a) Using suitable scales plot a graph of dry mass against time

(b) Write reference to the graph, explain the changes in dry mass between:-

(i) Week 0 to 2

(ii) Week 5 to 13

(iii) Week 16 – 18

(ii) What difference would be expected from the above results if the experiment started with

the seeds? Give a reason for your answer

(d) (i) Describe how you carry out the experiment to obtain dry mass in the respective weeks

(ii) State one advantage of using dry mass instead of fresh weight in estimating growth of an

organism

The diagram below represents a set-up that was used to investigate the effect of rotation on the

growth of a bean radicle. The set-up allowed the seedling to rotate slowly and continuously for

seven days

(a) Name the piece of apparatus illustrated

(b) (i) State the observation made on the shape of the radicle after seven days

(ii) Explain the observation in (b) (i) above

(d) Give any four importance of tropism in plants

An experiment was carried out to determine the growth rates of variety of bamboo and a variety of maize in two adjacent plots. The average height and average dry weight of plants from the two

populations were determined over a period of twenty weeks. The data is as shown below:-

a) On the same axes, plot a graph to show the changes in average weight of the bamboo and maize

plants over time

(b) (i) Which of the two plants had a higher productivity by the end of the experiment?

(ii) Give a reason for your answer in (b)(i) above

(i) Between weeks 14 and 18 the average height of maize plants remained constant while the

average dry weight increased

(ii) Dry weight was used instead of fresh weight in this experiment

(iii) Describe how the average height and average dry weight of plants were determined in

this experiment;

(d) Why was it appropriate in this experiment to use both weight and height?

(e) Give a reason why secondary thickening does not occur in bamboo and maize plants

(a) What is meant by the term fertilization ?

(b) (i) Name the type of cell division that produces gametes

(ii) Where does the type of cell division mentioned above occur in mammals?

(i) before the release of an egg ?

(ii) if no fertilization occurs?

(b) How is the placenta adapted to its functions?

The relationship between seed fresh mass in the lupin lupinus and percentage seed germination,

percentage seedling survival and seedling fresh mass is shown in the table;

Seed fresh

Mass mg^-1

Percentage

germination

Percentage of seedlings surviving 2 leaf stage

Mean seedling fresh mass 5 weeks after germination/mg

Below 16

17-25

26-35

36-45

Above 45

41.9

90.2

95.6

97.5

100.0

84.6

96.8

98.8

100.0

24.3

44.2

60.7

86.4

106.4

a) How was percentage germination in column two of the table calculated?
b) Why was seed fresh mass preferred to seed dry mass to take measurements of the seed weight

in the experiment

c) i) Explain why the measurements of mean seedling fresh mass (5) weeks after germinated

may not have been an accurate measurement of growth that had occurred

ii) How could more meaningful and accurate measurement been obtained in c(i) above?
d) With reference to the figures in the taste indicate the relationship between seed fresh mass

and percentage seed germination, percentage seedling survival and seedling fresh mass

e) Suggest an explanation why seedling produced from large seeds grow more rapidly than the

seedling produced from small seeds

The diagram below illustrate enzyme controlled reaction

a) State the relationship between rate of reaction and enzyme concentration
b) Account for the rate of reactions between; i) Q and R
ii) R and S

iii) U and V

c) Name one other factor that affects enzyme action, not illustrated above
Carefully study the figure below and answer the questions that follow:-

The seedling with straight radicle and plumule was attached to a machine horizontally as shown

above. The machine rotates making one revolution in 15minutes.

(a) Draw how the seedling would look like after one week

(b) Explain your drawing in (a) above

(d) What would happen if the seedling was put horizontally outside the machine

(e) Name the stimuli investigated and type(s) of response expected in the experiment

(a) Give the form in which each of the following substances ate transport in mammalian blood:

(i) Carbon (IV) oxide

(ii) Oxygen

(b) Give two functions of pleural membrane

(d) Other than stomata, name two other gaseous exchange surfaces in plants

In an experiment the radicle of a seedling was marked equidistant using Indian ink as shown

in the diagram below:

(a) What was the aim of the experiment?

(b) On the diagram below mark on the radicle to show the appearance of the marks after 3days

(c ) State three characteristics of cells found just behind the root cap of a radicle

(d) Give two factors inside a seed that causes seed dormancy

Genetics
A woman with blood group A gave birth to twins both having blood group AB.

Determine the genotype of:

a) Father
b) Mother
50 black mice and 50 white mice were released into an area inhabited by a pair of owls. After four

months, the mice in the area were recaptured and only 38 of the black mice and 9 of the white

mice were remaining.

a) How would this observation be explained ?
b) Name the theory of evolution that supports the results in (a)
State three mechanisms that prevent self pollination in a flower that has both male and female

Parts.

(a) Distinguish between complete and incomplete dominance

(b) State two sources of variation

Part of one strand of a DNA molecule was found to have the following base sequence.

G – T – C – A – G – T

(a) What is the sequence on m-RNA strand copied from this DNA portion?

(b) State two roles of DNA molecule.

State three ways by which plants compensate for lack of ability to move from one place to

another.

A student mixed a sample of urine from a person with Benedict’s solution and heated, the colour

changed to orange.

(a) What was present in the urine sample?

(b) What did the student conclude on the health status of the person?

Differentiate between continuous and discontinuous variations
Members of the same species of organism tend to differ due to variation. State three causes of

variation in organisms

Identify the type of gene mutations represented by the following pairs of words:-

(i) Shirt instead of skirt

(ii) Hopping instead of shopping

(iii) Eat instead of tea

A DNA stand has the following base sequence: GCCTAGATCAC
What is the sequence of the : (i) Complementary DNA strand?

(ii) M-RNA strand coped form this DNA strand

The figure below represents the distribution of height of pupils in a school

(a) Name the type of variation represented by the curve

(b) Outline two possible causes of variation in height of individuals in man

a) Wekesa and Wanjiku who are siblings are both normal as their parents but have a hemophilic

brother. Give the Genotype of their parents.

b) i)What are linked genes?
ii) What do you understand by the phase a test cross?
There are at least 205 known sex – linked recessive disorder
a) Name any two of them.
b) State a reason why sex – linked recessive why traits tend to effect the male child.
c) State why if a mother has the trait all her sons will have it
The table below is a representation of a chromatide with genes along its length. It undergoes

mutation to appear as shown below:

Before mutation	L	M	N	O	P	Q
After mutation	L	O	N	M	P	Q

a) Name the type of chromosomal mutation represented
b) Name one mutagenic agent
The figure below is a structural diagram of a portion from a nucleic acid strand
a) Giving a reason, name the nucleic acid to which the portion belongs
b) Write down the sequence of bases of a complementary DNA strand
In an experiment, plants with red flowers was crossed with plants with white flowers.

All the plants in the F₁ generation had pink flowers.

a) Give a reason for the appearance of pink flowers in the F₁ generation
b) If plants in F₁ were selfed, state the phenotypic ratio of the F₂ generation
c) Explain; i) Why women should drink extra milk during pregnancy
ii) A pregnant women might want to urinate more often in late pregnancy
State the meaning of the following terms giving an example in each case:

(a) Sex-linked genes

(b) Multiple alleles

In a certain breeding experiment, a plant species with red flowers was selfed. It produced 119

red flowered and 41 white flowered offsprings.

(a) Using letter R to represent allele for the red flowers, state the genotype of the red flowered

parent plant

(b) Determine the phenotypic ratio of red and white flowered plants. Show your working

Give an example of a sex-linked trait in human on: (i) Y – Chromosome

(ii) X – Chromosome

Explain why growth of long hair on the pinnae of the ears in human occurs in males only
Explain why prophase 1 of meiosis contributes towards genetic variation in living

organisms.

A pure Red flowered plant was crossed with a pure white flowered plant. All the F₁ generation

plants had pink flowers.

(a) Give an explanation for the absence of Red and white flowered plants in the F₁ generation. (b) If the F₁ generation pea plants were selfed, state the phenotypic ratio of the F₂generation

plants.

(a) Name a genetic disorder due to gene mutation that affects the malpighian layer of the

skin in man.

(b) Give two functions of the fluid produced by sebaceous glands.

(a) Define the term “Gene mutation.”

(b) Name the genetic disorders that result from gene mutation in human beings.

(i) What are mutations

(ii) Name two mutagens

A section of a DNA strand contains the following sequence CGGATAC

(a) Write the; (i) Complementary DNA strand

(ii) MRNA strand

(b) Name the site for protein synthesis in a cell

In a certain bird species, red flight feathers is controlled by gene R while white flight feathers is

controlled by gene r. The heterozygous condition Rr results into pink flight feathers. The two

genes are also sex linked and transmitted on x-chromosome.

a) By use of fusion lines, find the genotypes of across between a male with pink flight

feathers and a female with white flight feathers

b) Which type of dominance is illustrated here?
c) i)Identify the nucleic acid whose base sequence is shown below:

G-A-C-U-A-G-A-C-G

ii) Give a reason for your answer in c (i) above

iii) If the nucleic acid was involved in protein synthesis, how many amino acids would be

present in the protein synthesized? Give a reason

Study the genetic chart below showing the inheritance of the gene responsible for haemophilia

in a family.

a) Write the genotype of individuals A, B, F
b) A member of this family labelled F marries a haemophiliac male. What will be the phenotypic

ratio of the offspring? Show your workings

c) Other than the condition stated above, state any other two common genetic disorders that

result from gene mutation.

Haemophilia is due to a recessive gene. The gene is sex-linked and located on X chromosome.

The chart below represents the offspring of parents who are phenotypically normal for

haemophillia

(i) What are the parental genotypes?

Explain your answer in (i) above

(ii) Work out the genotypes of the offspring

A cross between a red-flowered and a white flowered plant produced only pink –flowered

F₁plants

(a) There was neither a red nor white –flowered F₁ plants. Explain

(b) The F₁ offspring were selfed to get F₂ generation. Using appropriate letter symbols, work

out the genotypes of F₂ generation

(d) Distinguish between dominant and recessive genes

A true-breeding purple maize variety was cross-pollinated with a true-breeding yellow

maize variety.

The offspring produced all purple fruits.

The plants grown from these F₁ grains were interbred among each other.

A typical cob of F₂ generation is shown below:

The yellow fruits are shaded while the purple ones are un-shaded.

(a) (i) In terms of flowers only, state why it is easier to work out genetic crossings using maize

(ii) Count separately the yellow and purple grains and therefore find the rations of purple

grains to yellow grains

(b) Using appropriate symbol, work out a genetic cross for F₂ generation

(d) State two practical applications of genetics in identity determination

The figure below is a pedigree chart showing incidence of albinism which is transmitted through a

recessive gene-a. Study and answer questions that follow;

(a) Write down the genotype of persons 1 and 2. Give a reason for your answer

(b) Giving your reason state the most likely genotype of person 3

why it is not advisable for close relatives to marry

(d) Apart from albinism name two other effects of gene mutation

The table below shows results of test to determine blood groups of persons Y and Z.A tick (√)

Represents, agglutination while a cross (x) represents no agglutination;

Person

Test with

antibody (a)

Test with

antibody (b)

Test with

Rhesus antibody

Blood group

Y- (male)

√

X- (female)

√

(a) Fill the blank space in table to show the blood group of the persons Y and Z

(b) In order to investigate the inheritance of Rhesus factor, work out a cross between a male

with Rh⁺ and female with Rh^– .Let D represent the presence of Rhesus factor and d to

represent the absence of the Rhesus factor

(d)Which of the children can donate blood to their mother?

Describe the behavioural adaptations of animals to temperature
In man blood group inheritance is controlled by multiple alleles in which allele A is co dominant

to allele B. a woman laterozygous for blood group A married a man heterozygous for blood

group B

a) State the genotype of both parents
b) Using a pun net square, show the genotypes of F₁ generation
c) State one application of knowledge of blood group inheritance in man
d) The nitrogenous bases in nucleic acids are Adenine (A), cytosine(C), Guanine (G),

Thiamine (T) and uracil (U). Input of a molecule of DNA the sequence of bases is CTT.

Using the letters A, C, G, T, U where appropriate, write down the base sequence in;

i) Corresponding part of the complementary strand of DNA molecules
ii) Corresponding part in mRNA

iii) A change in the DNA molecules caused the base sequence in the triplets to change from

CTT to CAT. State one factor which could have caused the change

In an investigation plants with red flowers were crossed with plants with white flowers. All the

plants in the F₁ generation had pink flowers when the F₁plants were crossed, he counted 480

plants in F₂ generation

(a) Using appropriate letter symbols, work out the cross between the F₁ plants to get the F₂

generation

(b) Give the phenotypic and genotypic ratios for the F₂ generation

Phenotypic ratio

Genotypic ratio

In an experiment, a black mouse was mated with a brown mouse. All the off springs in F₁

generation were black. The off springs grew and were allowed to mate with one another. The total

number of F₂ generation offspring were 96.

(a) Using letter B to denote the gene for black colour. Work out the genotype of the F₁generation.

(Use a punnet square)

(b) State the following for the F₂ generation

(i) Genotypic ratio

(ii) Phenotypic ratio

(iii) The total number of brown mice

(a) Distinguish between Homologous structures and analogous structures. Give an example

in each case.

Homologous structures

Example

Analogous structures

Example

(b) Explain why parasites develop resistance to certain drugs after a long time of exposure.

(ii) Give one example of a genetic disorder associated with non-disjunction .

Evolution
a) Distinguish between homologous and analogous structures in evolution. b) Name one vestigial structure in mammals.
a) Give two examples of adaptive radiation in animals.
b) State two disadvantages of using fossils as evidence of evolution
Distinguish between camouflage and mimicry.
State the role of light in photosynthesis
(a) Name the region of the gut where digestion of cellulose takes place.

(b) State role of cardiac sphincter in the stomach.

(a) Give two limitations of fossil records as evidence of evolution

(b) State any two similarities in structure between Homo erectus and Homo Sapiens

(a) (i) What is meant by vestigial structures?

(ii) Give an example of a vestigial structure in human

Distinguish between the struggle for existence and survival for the fittest as used in the theory of

natural selection

Give two factors that determine water reabsorption in the distal convulated tubule
Distinguish divergent and convergent evolution
(a) What are the advantages of natural selection

(b) All insects are believed to have arisen from a common ancestor. However, modern insects

differ widely in a variety of ways such as in the adaptation of their mouthparts for different

modes of feeding. What kind of evolution is this?

Explain why Lamacks theory of evolution is not accepted by Biologists today.
a) i) What is meant by vestigal structures
ii) Give an example of vestigal structure in human
b) Explain why certain drugs become ineffective in curing a disease after many years of use
(a) What is organic evolution?

(b) Briefly explain the term “survival for the fittest” as used in Darwin’s theory of natural

selection

Explain why insecticides become ineffective against insects if used for several years in succession
State three limitations of fossils records as an evidence of organic evolution
State three pieces of evidence that support the theory of organic evolution
What is meant by natural selection?
(a) Explain why Lamarcks theory of evolution is not accepted today

(b) State two limitations of fossils records as evidence of organic evolution

In a breeding experiment, plants with red flowers were crossed. They produced 123 plants with red flowers and 41 with white flowers:

(a) Identify the recessive trait

(b) Give a reason for your answer

Show your working using appropriate symbols (R, r)

(d) What is a test cross?

a) What is organic evolution?
b) Describe the various evidences which support the theory of organic evolution.
(a) What is meant by the term natural selection

(b) Describe how natural selection brings about the adaptations of a species to its environment

(d) Discuss four evidences to show that evolution has taken place

Explain the various evidence for organic evolution
(a) What is organic evolution

(b) Explain why resistance to antibiotics is considered as an example of evolution

Pure breed red flowered plants were cross pollinated with pure breed white flowered plants.

The resulting F_loffspring’s had pink flowers.

(a) Using letter R to represent the gene for red colour and letter W to represent gene for white

colour of flowers. Work out the genotype of the F₁ generation

(b) If seeds from the F_l generation plants were planted and allowed to self pollinate. Work out

the phenotypic ratio of the F₂ generation

Irritability and sensitivity in (a) plants (b) animals
Give two functions of the exoskeleton in arthropods.
When shoots of young plants are exposed to unidirectional light they bend towards light;
a) Name the type of response exhibited by the young shoots
b) Explain the cause of the observation above
Study the drawing below and use it to answer the questions that follow :-

a) Name the part labeled
b) Describe the changes that occur in the structure X in dim light.
c) What is meant by the term accommodation with reference to the eye?
(a) State two differences between taxes and tropisms

(b) Give two survival values of tactic movements to organisms

The diagram below represents a type of neurone.

(a) (i) identify the neuron above.

(ii) Give a reason for your answer in a (i) above.

(b) With an arrow, indicate on the diagram the direction of an impulse through the neurone.

A student was traveling from Nairobi to Mombasa. As the bus descended down hill he felt an

unpleasant sensation in the ear.

(a) How did the sensation come about? *

(b) How can the unpleasant sensation be relieved?

An experiment was carried out to investigate a growth response in maize seedling as shown

in the diagram below:

(a) State the type of response that is being investigated ………..

(b) Explain the response exhibited by the shoot

State three genetic disorders caused by gene mutations
The diagram below shows the position of an image formed in a defective eye:-

(a) Name the defect

(b)Explain how the defect named in (a) above can be corrected

(a) State three structural differences between arteries and veins in mammals

(b) Name a disease that causes thickening and hardening of arteries

(a) Name the part of the eye in which the light sensitive cells are located

(b) List the two types of sensory cells found in the part named in (a) above

The diagram below illustrates a certain eye defect

(a) State the defect

(b) On the diagram illustrate how the defect can be corrected

Briefly explain the role of the following part of skin
a) Cornified layer
b) Malpighian layer
State the functions of the following structures of the mammalian ear
a) Eustachian tube
b) Essicles
a) Distinguish between conditioned and simple reflexes
b) State how the nerve cell structure is suited to its function of impulse transmission
(a) Name the part of the mammalian eye that:

(i) Transmits impulses to the brain

(ii) Regulates the amount of light entering the eye (b) State the changes that occur in the part of the eye named in (a) (ii) above when one moved

from bright light to dim light conditions

Name the type of response exhibited by the following:

(a) A pollen tube growing towards the embryo sac

(b) Maggots moving from lit side of a box to the dark side

A response exhibited by a certain plant tendril is illustrated below:

(i) Name the type of response

(ii) Explain how the response named in (i) above occurs

A response exhibited by a certain plant tendril is illustrated below:-

Name the type of response

Removal of the apical bud from a shrub is a practice that results in the development of many

lateral buds which later form branches

(a) Give reasons for the development of lateral branches after the removal of the apical bud

(b) Suggest one application of this practice?

In an accident a victim suffered brain injury. Consequently he had loss of memory which

part of the brain was damaged?

A person was able to read a book clearly at arm’s length but not at normal reading distance (a) State the eye defect the person suffered from

(b) Why was he unable to read the book clearly at normal distance?

The diagram below represents a simple reflex arc;

(a) Name the parts labeled A and B

(b) Explain how an impulse is transmitted across the gap labeled C

(a) State two functions of a mammalian ear

(b) How is the cochlea suited to its function

State one function of potassium ions in the human body.
State two functions of vitamin B₅ (pantothenic acid).
(a) What is the biological importance of tactic responses?

(b) A person had an accident and had problems with his vision, hearing and memory.

Identify the part of the brain that was affected

Identify the following responses shown by plants:- (a) Shoots grow towards light

(b) Roots grow towards gravity

Name the type of responses exhibited by:-

(a) (i) Marine crabs burrowing into the sand to avoid dilution of their body fluids

(ii) Chlamy domonas plant moving towards a region of high light intensity

(b) (i)What type of neuron is drawn above?

(ii) Using an arrow, show the direction of the nerve impulse

(iii) Name the part labelled X

(iv) State the function of part labelled Y .

In an experiment to investigate the effect of heat on germination of seeds, 12bags each

Containing 60 pea seeds were placed in a water bath maintained at 85^oC .

After every two minutes a bag was removed and seeds contained in it planted. The number that

germinated was recorded. The procedure used for pea seeds was repeated for wattle seeds. The

results were as shown in the table below:-

Number of seeds that germinated

Time (min)

Pea seeds

Wattle seed

(a) Using a suitable scale and same axes, draw graphs of number of seeds that germinated against

time in hot water for each plant

(b) (i) At what time would number of seeds that germinated for each plant be same?

(ii) How many wattle seeds would have germinated if the 13^th bag was available and was

removed and seeds contained in it planted at 24minutes?

(d) Explain why the ability of the wattle seeds to germinate improved with time of exposure

to heat

(e) Account for the shape of the graph for the wattle seeds which germinated between 20-24

minutes (f) Some of the pea seeds were allowed to germinate and placed in a large air tight flask

and left for four days:-

(i) Suggest the expected changes in the composition of gases in the flask on the fifth day

(ii) Give reasons for your answer in (f)(i) above

(g) Name three factors other than those investigated in (a) above which would affect dormancy

How is the mammalian skin adapted to its functions?
Explain how the mammalian skin is adapted to it’s functions
Explain the structure and functions of the human eye.
The diagram below shows the position of an image in a defective eye.

(a) (i) Name the defect

(ii) State the causes of the defect

(b) Explain how the defect in a(i) above can be corrected.

(d) How are nocturnal animals adapted to seeing?

Support and movement in (a) Plants (b) animals
Explain how the following tissues are adapted to provide mechanical support in plants:-
a) Parenchyma
b) Collenchyma c) Selerenchyma
The diagram below represents a bone in the mammalian skeleton

a) Identify the bone with a reason
b) State the function of the part labeled D
The diagram below represents a mammalian bone

(a) Identify the bone shown above

(b) State the function of the parts labelled R and S

(i) Name two bones that form the ball and socket joint in the fore limb of a mammal

(ii) Name the fluid that is found in the above mentioned joint and its function

State three types of skeleton found in Kingdom animalia
State three differences between an animal’s muscle cell and plant’s palisade cell
The diagram below represents a mammalian bone

(a)Name the bone

(b) (i) Which bone articulates with the bone shown in the diagram at the notch

(ii) Name the type of joint formed when the bones in b(i) articulate

(a) Name the hard outer covering of the members of the phylum Arthropoda

(b) State two roles played by the structure named in (a) above

(a) State the role of lignin in the wall of the xylem vessel

(b) How does vascular bundles contribute to support in plants

(a) Distinguish between tendons and ligaments
b) State one way through which herbaceous plants achieve support
Name the ;
a) i) Material used to strengthen the xylem tissue
ii) Tissue that is removed when the bark of a dicotyledonous plant is ringed
b) State the areas of the plant where translocated materials are taken
Give three importance of mammalian skeleton
The diagram below represents the anterior view of a rib

Name the part labelled X

The diagram below represents a bone obtained from a mammal

a) Name the bone

b) Name the:
i) Bones which articulate with the bone named in (a) above at the cavity labelled K
ii) Joint formed by the two bones at K
c) State functions of part labelled J

The diagram below represents a bone obtained from a mammalian skeleton:

(a) Identify the bone

(b) Name the:

(i) Bone it articulates with at point A

(ii) Type of joint that forms at point B in articulation with other bones

The diagram below represents a bone obtained form a mammal

(a) Identify the bone

(b) Name the structures labeled X and W

(a) Name the vertebra in a mammalian body that is characterised by presence of odontoid

process.

(b) State the function of the odontoid process

a) Name three supporting tissues in plants
b) Study the diagram below and answer the questions which follow:

i) Identify the muscle represented by X and Y
ii) Describe how muscles x and y cause straightening of the joint z
c) Name the joint z
(a) What is the importance of locomotion in animals? (b) Explain how a bony fish is adapted for movement in its habitat

Human health
a) Name the causative agent of cholera.
b) Name the intermediate hosts in the life cycle of the following parasites;
i) Ascaris
ii) Schistosoma
c) How does the parasite plasmodium vivax gain entry into its host?
The graph below shows body temperature of a patient suffering from malaria

(a) What symptom of the disease is shown in the graph?

(b) Name the organism that causes malaria

Name the causative agent of typhoid
Malaria is a common disease in Kenya:-

(a) What causes the disease?

(b) State one control measure of the disease

a) Name the causative agents of the following disease in humans:-
i) Typhoid;
ii) Amoebic dysentery;
b) Name the disease in human cased by plasmodium falciparum
Below are diagrams of disease causing micro-organisms. Use them to answer the questions that follow:

(a) State the kingdom to which they are found.

(b) Name the diseases caused by the organisms: A and B (c) State one way in which the disease named for organism B can be prevented

Explain why it is important to go for voluntary counseling and testing (VCT) on HIV/AIDS
Name one human disease caused by each of the following parasites.

(a) Plasmodium falciparum……………………………………………………

(b) Entamoeba histolytica …………………………………………………….

SECTION I & II MARKING SCHEME

Classification I &II
arachnida; crustacean;

– Body is covered by fur or hair;

– Have mammary glands (for milk production);

– Have external earlobes;

– Have highly developed brain;

– Have muscular diaphragm that have sweat glands;

– Have muscular diaphragm (that thoracic cavity from abdominal cavity); (first three)

– Two names i.e first genus and second species;

– Genus names starts with capital letter while species starts with small letter;

– Both names are written in italics, when printed or underlined when types or handwritten;

(a) Kingdom Monera;

(b) Producing antibiotics; vaccines; hormones and in producing transigenic organisms in modern

technology;

Chordata;

a) Fungi;
b) Sporulation;

Prothoraic glands disintegrates hence no production of ecdysone / moulting hormone

Zoology;

– Mushrooms used as food;

– penicilium are used to make antibiotic;

– Yeast is used in brewing and bread baking;

Sub-division – Angiospermaphyta;

Class – Dicotyledonae;

arachnida;

(a) (i) Fungi/mycophyta:

(ii) Non— green/ lacks chlorophyll;

– Body made up of hyphae/ mycelia;

(b) (Asexual) reproduction: OW WTE

(a) taxonomy is the classification of living organisms on their similarities and difference observed

(b) (i) Rottus norvegicus (1mk) (Genus name MUST begin with capital letter and be underlined

separately)

(ii) Genus – Rattus;

Species – norvegicus;

– A segmented body;

– A hard exoskeleton;

– Jointed legs;

The cell – structure & functions of organelles
a) Lysosomes;
b) Contractile vacuoles;

(a) Make cells visible;

(b) Prevent distortion of cells;

Diameter of field of view

= 4mm x 1000mm = 4000µm;

Size of each cell = 4000

= 200µm;

a)Manufacture of ribosomes;
b) encloses cell contents; regulate movement of materials in and out of the cell;

Protein:

Nucleic acid (DNA – RNA);

(i) Mg = O.L.M x E.L.M;

= 100 x 5

= x500;

(ii) x 500 = 5 x 10,000 = 50000mµ

x 1 = ?

= 1 x 50,000;

500

= 100micrometer;

a) mitochondria;

b ) -has cristae/inner membrane highly folded to increase surface area; for respiration.

-Has matrix medium for respiratory activities; (reject (b) if (a) is wrong.)

a) nucleolus;
b) Centrioles;
c) nuclear membrane/pore;
a) catalyses the breakdown of toxic hydrogen peroxide; to harmless water and oxygen in

active tissues;

b) Low temperature;

a) i) Nucleus.
ii) Formation of RNA / ribonucleic acid;

Formation of ribosomes;

b) i) Contractile vacuole;
ii) Lysosomes;

Sensitive to change in temp; sensitive to changes in PH; has both negative and positive

charges;

a) Cellulose;
b) Store sugars, salt and food; carry out osmoregulation by inducing osmotic gradient that

bring about water movement; maintain the shape of the cell;

c) Cell wall; and chloroplast;

Study of internal and external parts of the body of an organism; Study of the living organisms and their chemical composition;

a) Synthesis of proteins;
b) Site for photosynthesis;

a) Length of drawing ;

Length of object

(a) Ribosomes:- Protein synthesis(1mk);

(b) Centrioles – Spindle formation during cell division ;

– Form cilia and flagella

(a) cellulose;

(b) Lipoproteins/lipids and proteins;

– No organized nucleus;

– Organelles not bound by membranes;

– Lack mitochondria;

(a) X : Chloplasts;

Y : Vacuole /sap vacuole;

(b) More on the upper side to obtain optimum light intensity/ in bright light, they move away to

avoid bleaching/ in dim light they move towards the source of light for maximum

absorption of light;

Cell diameter = field of view in menometer

Number of cells under the field of view

3.5×1000 ; 3500;

8 8

= 437.6mm = 438mm;

i) Arachnida
ii) – Exoskeleton

– Jointed appendages

– Segmented body

– Moulting;

22 a) Magnification – Ability of a microscope to enlarge tiny objects

Resolution – Ability of a microscope to separate between two tiny structures under

magnification to appear distinct

b) Mounting – The placing of prepared slide on stage of a microscope;

Staining – Use of chemical stain on specimen for clear observation

(a) Golgi bodies/Golgi apparatus;

(b) Lysosome(s):

(c ) Ribosomes;

(a) Make the sections transparent:

(b) To produce thin sections/ Not to distort the cells:

(c ) To distinguish between different parts/organelles of the cells:

– Magnify the object further;

– Concentrates light onto the object;

– Controls amount of light illuminating the object;

Size of one cell = diameter of field view

No. of cells arranged across the diameter

= 2000mm;

10cells

200mm = 0.2mm

N/B = 1mm = 0.001mms;

(a) To make the specimen /section more visible

(b) To allow light to pass through for easy viewing

Animal cell;

a) Stores hydrolytic enzymes for destruction of worn out organelles/ cells/ tissues/ digestion

of bacteria/ pathogens; Acc digestion of food/ accept autolysis

b) Processing/ packaging synthesized and transporting of packaged cell materials; production

of lysosomes/ secretions of packaged material;

Insecta; Reject insects/ exopoda

a) magnifying the image of the specimen;
b) Objective lens brings the image into focus and magnifies it;

a) Mitochondria
b) early production/ respiration;
c) Increases surface area; for attachment of respiratory enzymes;
d) Nerve cells; skeletal muscles; cardiac muscles

Cell Physiology – Osmosis, Diffusion and Active transport

a) A- The strip increased in length/ size; B – Decreased in length/ size;

b)The sugar solution was hypotonic to the cell sap strip A; it gained water by osmosis

hence increasing in length;

(a) The potato cup will be filled with solution;

(b) The solution in the potato cells is hypertonic to the water; hence water moves into the cell by

osmosis; this makes the solution in the neighbouring cells to be hypertonic to the outer cells;

hence water moves from cell to cell until it eventually enters the potato cup;

(a) (i) Will lose water by osmosis and become plasmolysed;

Diffusion;

Osmosis ;

Active transport ;

5 a) 3.0 + 3.1 + 3.2 = 9.3 g;

Average = 9.3 = 3.1g;

b) The cell sap had a higher concentration of solutes than distilled water, water therefore

moves from the environment to the cell by osmosis ;

(a) red blood cells placed in a hypertonic solution and as a result lost water to the surrounding

thorough osmosis hence shrunk/crenated ;

(b) Appearance of that cell if subjected to the same condition

a) Haemolysis
b) Plant cell will lose water the cell sap to the outside solution by osmosis; the cell

becomes plamolysed/ flaccid; but it will retain its shape due to rigid cell wall;

a) Haemolysis ;
b) The plant cell will draw in water molecules by osmosis; it will swell and become turgid; but it

will not burst because of the presence of cellulose cell wall;

i) Spermatozoon

– Tail – For swimming in vagina tract

– Numerous mitochondria – for provision of energy for swimming

– Streamlined – to reduce friction during movement

– Haploid nucleus – for fertilization of haploid ovum

Palisade mesophyll cell

– Numerous chloroplasts for photosynthesis

– Narrow and cylindrical – packed in small space

– Large sap vacuole for storage of manufactured food;

a) Prophase I Reject prophase alone
b) Homologous Chromosomes side by side or Bivalency

c_)

Mitosis	Meiosis
One phase	Two phases
Diploid daughter cells	Haploid daughter
No chiasmata formation	Chiasmata formation; Any two correct

Trophism	Tactic response
Growth is involved or brought about cell division	Locomotary
Slow	Fast

Set -up		Number of red blood cells
	Sodium chloride concentration	At start of experiment	At the end of the experiment
A	0.9%	Normal	No change in number
B	0.3%	Normal	Fewer in number

A-no change in; number because 0.9% sodium chlorine solution is isotonic to RBC/blood;

B-fewer in number because 0.3% sodium chloride solution is hypotonic to RBC/blood

therefore some water was drawn in to RDC by osmosis ;leading to haemolysis/boosting of

RBCs

b)i)number will not change;

ii)RBC will appear small in size/wrinkled/crenated/shriveled/shrink; 1mk

Rej. Flaccid/flabby/plasmolysed

(i) Paranchyma;

(ii) Collenchyma;

(iii) Xylem: and sclerenchyma

(a) X – hypotonic solution; p

Y – hypertonic solution; p

(b) A – haemolysis; p.

B – crenation /laking; p

Absorption of mineral salts by root hairs from the soil; Translocation of food from

leaves to other parts of the plant; movement of salts from one cell to the next;

(a) (i) Increased in length, absorbed water through osmosis, ( since cylinder cells were

hypertonic/ at higher concentration) and become turgid.

(ii) Reduced in length, cylinder host water to the hypertonic sucrose solution/become flaccid.

(b) (i) No change in length

(ii) Cells are dead and cannot carry out osmosis.

Support in plants
Movement of water from cell to cell
Feeding in insectivorous plants
Absorption of water by root hairs
Absorption of water in the intestines
Reabsorption of water in kidney nephron.

(a) (i) Nucleus

(ii) Maintain the shape of he cell providing support to herbaceous plants; stores sugar

and salts; (mark first one)

(b) 0.5 x 100 ; 62.5µm;

Accept -highly concentrated salt/sugar solution

(d) The potato cell sap were lowly concentrated than the surrounding solution; hence lost water

molecules by osmosis through the semi permeable membrane to become plasmolysed;

(e) Re-absorption of water from the kidney tubules/ hence important in osmoregulation;

a) transpiration
b) prevent evaporation of water from the surface
c) the level of water dropper
d) i) faster drop in water level ii) no change in water level;

iii) slower/very slow drop in water level;

e) another set up using a leafless twig;

Nutrition in (a) plants (b) animals

a) Condensation;
b) water;

(a) Guard cells;

(b) Cells walls are thicker on the inner side then the outer side; which enables them to pull

inwards when the cells are turgid; contains chloroplasts that are able to phosynthesize

and produce sugars which enable them to absorb water; (any two points)

which favours conversion of sugar to starch; causing the guard wells to lose turgidity; and

close;

(a) Stomata on the epidermic were blocked; thus no carbon (IV) oxide entered the heat;

therefore photosynthesis did not take place;

(b) Respiration; Excretion/ transpitation;

Etiolated plant

Normal plant

– Yellow leaves/stems

– small leaves

– long inter-nodes and thin stems

– weak stem/feeble stem

– green leaves/stems;

– large leaves;

– short internodes and thick stem;

– strong /firm stem;

(b) Enables plants to grow faster towards light for photosynthesis;

PLANTS	ANIMALS
– Make their own food through the process of photosynthesis	– Depend on plants and other animals for food;
– They do not move from one place to another	– They move from one place to another;
– Respond slowly to stimuli	– Respond faster /quickly to stimuli;

They have thick inner membrane and thin outer membrane to allow them to bulge

outwards when turgid to open stomata; Have numerous chloroplasts, to carryout photosynthesis, forming sugars to control opening and closing of stomata;

Reaction A – condensation;

Enzyme Y – Sucrose;

– To emulsify fats;

– To provide an alkaline condition for enzyme activities;

Have stomata on upper surface;

– Large leaf surface to increase surface are for absorption of light;

– Presence of aerenchyma tissues, allows them to float on water hence accessing sunlight;

(a) – Protease;

– Lipase

(b) At 35^oC optimum temperature for enzyme to act; at 15^oC enzymes in active since

temperature is low;

a) Goiter;
b) Scurvy;

Enzymes – Thrombin; Thromboplastin/ Thrombokinase;

Metal ion – Calcium ions;

a) Peristalsis;
b) Circular and longitudinal muscles on the wall of oesophagus and intestines contract

alternately;

c) Roughage;

Long gut / many chambers to provide large surface area for digestion; bacteria in rumen has

enzyme cellulase which digest cellulose (to glucose/ sugars).

Concentrated of the solutions separated by a semi-permeable membrane; existence of

concentration gradient; temperature of the solution;

i) Pancreas; ii) Insulin;

a) Roughage; b) Water, vitamins, mineral salts;

Photolysis – Splitting water into H⁺ and oxygen gas;

– Synthesis of ATP to be used during dark stage;

– Synthesis of chlorophyll necessary for photosynthesis;

Guard cells

Other epidermal cells

– Have chloroplasts/photosynthesize

– Have thick inner walls/thin outer walls

Bean shaped

– No chloroplasts/do not photosynthesize

– Walls uniformly thickened

block shaped (any correct pair )

(i) Biliverdin ; Bilirubin ;

(ii) Emulsify fats;

a) Involuntary movement of food along the alimentary canal
b) Rhythmic contraction and relaxation of the circular and longitudinal muscles along the gut;

22 . a) i) Chloroplast;

ii) Mitochondrion;
b) Similarity — Both have a double membrane;

Difference Chloroplast Mitochondrion;

– Grana Cristae;

– Stroma Matrix;

a) HCl — to hydrolyse complex sugar to simple sugar

NaHCO₃ — To neutralize the HC1

b) Disaccharides;
c) i) Glucose;
ii) Sucrose;
a) Sensory neuron;
b) Cell body is off the axon;
c) A — Conduct coming signals / Receives impulses;

B — Receives impulses rough dendrites / coordinates the nerve cell;

D — produce myclin sheath that protects and insulates the axon;

a) Increases surface area for attachment of respiratory enzymes;
b) i) Intergrana;
ii) Accept site 4 photolysis; contains chlorophyll pigment absorbs light;

a) Increases surface area of fats for purpose of digestion;
b) Accept any two correct

– Destroys any ingested pathogens;

– Provides acidic media for protein digesting enzymes (pepsin);

– Converts/ activates pepsinogen inactive form to pepsin;

Poison acts as competitive inhibitor for active site of respiratory enzymes; energy production

for active transport of nitrates is impaired;

Rhizobium bacteria benefits by getting Shelter & carbohydrates;

– Leguminous plant obtains nitrates fixed by the bacteria;

– Enzymes amylase digests starch to maltose

– Mucus lubricates food

They are converted to starch; then stored in organs and tissues;

-Guard cells have chloroplast;

-They are bean shaped;

Oxygen-releases to the atmosphere or used by plants for respiration;

Hydrogen-enter dark stage, where it combines with CO₂ to form simple sugar;

ATP- provide energy during the combination of hydrogen a toms with CO₂in dark stage;

a) to investigate the effect of boiled saliva on starch/to show the effect boiled/denature

enzyme amylase has on starch;

b) A-brown colour/colour of iodine persists;

B- blue black/blue/dark colouration;

c) A-starch has been digested/starch has been broken down/amylase hydrolyses starch hence

no colour changes;

B-enzymes/amylase denatured hence no starch digested;

a)A-condensation;

B-hydrolysis;

b)Duodenum; (any correct Rj .wrong spelling)

-ileum;

35 i)stroma

ii)side of light reaction of photosynthesis /site of water photosynthesis and adenosine

triphosphare production (ATP)

(i) (Vitamin D/calciferol;

(ii) Prevents rickets/Osteomalacia;

a) Schistosomiasis/ Bilharzia:
b) -Has suckers for attachment to the host:

Has secondary host/snail to increase its chances of survival:/increase chances of transfer to several hosts;
Its larvae/Eggs produces lytic enzyme to soften the hosts tissues hence allow prevention into the host:
Larva covered with cysts to remain dormant for a long time;
Goes through various forms of lifecycle/miracidia. cercariae and redia to make it difficult to eradicate/increase chance of survival/transmission;
Adult produces chemical substances to cover the body to protect it against hosts defence mechanism;
Separate sexes to ensure dispersed eggs are fertilized before shed into blood vessels.

(a) (i) Stomach

(ii) Presence of hydrochloric acid to provide acid conditions

39 (a) To investigate the effect of heat on salivary amylase.

(b) A – The brown colour of iodine was retained because the starch was digested by enzyme

amylase in the saliva; p 1.

B – The colour changed to blue black/black; because amylase in the saliva was denatured

by heat;

(a) (i) stroma; p

(ii) Granum; p

(b) – Provide energy – ATP;

– Provide H⁺– ves H₂ GAS /atoms;

Midnight – There was no photosynthesis at night; and carbon IV oxide was not used hence the

high concentration;

Noon – Carbon IV oxide was used in photosynthesis and therefore CO₂ concentration dropped.

– By increasing the enzyme /substrate concentration;

– By increasing the temperature below the optimum upto the optimum temperature;

– Providing suitable /favourable /optimum pH.

(a) – Mode of feeding is herbivorous. Reject Herbivore

– Absence of upper incisors but have hony pad

(b) 30

Small mammals have large surface area to volume ratio; hence lose heat quickly to environment; to replace the heat , lost, their metabolism is high making them to feed more frequently

– Plants are able to synthetize their own food

– Plants are able to use pollination rather rhan moving to seek mating partners

– Use seed and fruits dispersal to colonize new habitats (3×1=3mks)

a) A- Rhizome

B- Adventitious roots

(b) The liverwort body form is thalloid while the fern has 3body parts, roots, stem and leaves

The break down of glucose into pyruvic acid

Monosaccharide	Polysaccharides
– Are soluble in water	– Are insoluble in water
– Form sweet tasting solution	– Do not have a sweet taste
– Reduce Copper(II) ions in benedicts solution to Copper (I) ions when heated together	– They do not reduce
– Are crystalizable	– Are not crystallizable

(b) Peptide

H⁺/H atom; rej H2/Hydrogen gas

– ATP/energy

Absorption of water; accept absorption of salts/ calcium/ iron; secretion of mucus;

a) To show that light is necessary for photosynthesis;
b) Only the uncovered areas turned blue- black with iodine; the part covered with aluminum

foil did not receive light and thus could not carry out photosynthesis;

a) As the temperature increases, the rate of the reaction also increases; this happens because

an increase in temperature increases molecular movement, thus increasing the chances of

collision between the enzyme and substrate molecules;

b) X – is the optimum temperature/ It is the temperature at which the reaction proceeds

Nitrogen;

Magnesium;

Iron;

a) A- Hook;

B – Sucker;

C – Youngest proglottid;

b) Intermediate host – pig;

a) A – Villus

B- Lacteal

b) A __ Increases surface area for maximum digestion and absorption;

B – Absorption of fatty acid and glycerol;

c) – Final digestion of undigested foods;

– Absorption of soluble end products of digestion;

d) Produces bile juice which contains bile salts that emulcify fat;
e) Produces insulin and glucagons hormones;

Reject if only one hormone is mentioned

(a) Rapid increase (in water of photosynthesis) due to increase in concentration of CO₂

(b) Constant rate/no increase rate and no decrease, other factors /light/temperature water

become limiting/inadequate.

Light energy react water into hydrogen ions and oxygen/photolysis.

Hydrogen is picked by hydrogen.

Acceptor/NAD/NADP (and becomes reduce, * ACCEPT NADPH,NADPH

ATP adenosine triphosysbate formed.

(a) Compensation point

(b) (i) There is no net uptake or release of Carbon (VI) oxide by the plant;

(ii) The rate of respiration and photosynthesis in the plants are equal; therefore all the

Carbon (VI) Oxide released during respiration is used in photosynthesis;

respiration; and this requires a net uptake of Carbon (IV) Oxide (to sustain the increasing

rate of photosynthesis);

(d) Growth would cease because all the products of photosynthesis would be utilized in

respiration;

(e) The plant will take up oxygen from the surrounding air since the rate of respiration is

higher than the rate of photosynthesis;

(a) Broad and flat to absorb maximum light

Have chloroplast with chlorophyll to trap light.

Transparent cuticle to allow light to pass through

(b) X – Carbon (IV) Oxide

Y – Oxygen

Phloem – Sugars out of the leaf

(d) Starch is insoluble in water, hence osmotically inactive; This reduces effect on absorption of

water.

a) breakdown of complex food, substance; into simple diffusible substances; b)intestines relatively long/coiled /folded ;this allows food enough time for absorption.

Intestines long /have villi; to increase the surface area for absorption and digestion ;

The walls have glands which secrete enzymes for digestion;(examples of correct enzymes

e.g. Maltose, sucrose lactose etc).some glands /goblet cells also produce mucus; which protects

The intestinal wall from autodigestion/being digested; and reduce friction;

Intestines have opening of ducts which allows bile pancreatic juice into the lumen;

The intestines have circular and longitudinal muscle, whose contraction and relaxation/peristalsis;

Leads to mixing of food with enzymes/juice; facilitating rapid digestion and help push food along the gut; the intestines are well supplied with blood vessels to supply oxygen/ remove digested food from an efficient absorption and transporting system to move the food away from the small intestines;

Have lacteal vessels for transport of fat/lipid; have thin epithelial lining; to facilitating fast absorption /diffusion;

Note. Allow increases in surface are for absorption only once

(a) To investigate the rate of photosynthesis;

(b) It is used to draw the bubbles of gas through the apparatus;

Light energy

Chlorophyll

(ii) 6 CO₂ + 6H₂O C₆H₁₂O₆ + 6O₂^;

Acc. Either word or chemical equation

Light

Chlorophyll

If chemical, must be balanced, symbols capital.

or Carbon (IV) Oxide + water Glucose + Oxygen;

– Optimum

– Optimum PH

– Absence of inhibitors.

– Presence of co-factors or co-enzymes.

– Low substrate concentration.

(e) – To minimize temperature changes.

a) A- Rhizome

B- Adventitious roots

(b) The liverwort body form is thalloid while the fern has 3body parts, roots, stem and leaves

The break down of glucose into pyruvic acid

Monosaccharide	Polysaccharides
– Are soluble in water	– Are insoluble in water
– Form sweet tasting solution	– Do not have a sweet taste
– Reduce Copper(II) ions in benedicts solution to Copper (I) ions when heated together	– They do not reduce
– Are crystalizable	– Are not crystallizable

(b) Peptide

H⁺/H atom; rej H₂/Hydrogen gas

– ATP/energy

Absorption of water; accept absorption of salts/ calcium/ iron; secretion of mucus;
a) To show that light is necessary for photosynthesis;
b) Only the uncovered areas turned blue- black with iodine; the part covered with aluminum

foil did not receive light and thus could not carry out photosynthesis;

a) As the temperature increases, the rate of the reaction also increases; this happens because

an increase in temperature increases molecular movement, thus increasing the chances of

collision between the enzyme and substrate molecules;

b) X – is the optimum temperature/ It is the temperature at which the reaction proceeds

Nitrogen;

Magnesium;

Iron;

a) A- Hook;

B – Sucker;

C – Youngest proglottid;

b) Intermediate host – pig;

a) A – Villus

B- Lacteal

b) A __ Increases surface area for maximum digestion and absorption;

B – Absorption of fatty acid and glycerol;

c) – Final digestion of undigested foods;

– Absorption of soluble end products of digestion;

d) Produces bile juice which contains bile salts that emulcify fat;
e) Produces insulin and glucagons hormones; Reject if only one hormone is mentioned

(a) Rapid increase (in water of photosynthesis) due to increase in concentration of CO₂

(b) Constant rate/no increase rate and no decrease, other factors /light/temperature water

become limiting/inadequate.

Light energy react water into hydrogen ions and oxygen/photolysis.

Hydrogen is picked by hydrogen.

Acceptor/NAD/NADP (and becomes reduce, * Accept NADPH, NADPH

ATP adenosine triphosysbate formed.

(a) Compensation point

(b) (i) There is no net uptake or release of Carbon (VI) oxide by the plant;

(ii) The rate of respiration and photosynthesis in the plants are equal; therefore all the

Carbon (VI) Oxide released during respiration is used in photosynthesis;

respiration; and this requires a net uptake of Carbon (IV) Oxide (to sustain the increasing

rate of photosynthesis);

(d) Growth would cease because all the products of photosynthesis would be utilized in

respiration;

(e) The plant will take up oxygen from the surrounding air since the rate of respiration is

higher than the rate of photosynthesis;

(a) Broad and flat to absorb maximum light

Have chloroplast with chlorophyll to trap light.

Transparent cuticle to allow light to pass through

(b) X – Carbon (IV) Oxide

Y – Oxygen

Phloem – Sugars out of the leaf

(d) Starch is insoluble in water, hence osmotically inactive; This reduces effect on absorption of

water.

a) breakdown of complex food, substance; into simple diffusible substances; b)intestines relatively long/coiled /folded ;this allows food enough time for absorption.