A little starch solution was kept in a water bath at 37ºC. After a few minutes, the same volume of saliva was added. The experiment was left to stand for 15minutes. The mixture was then tested with Benedict’s solution.
a) What would you do to the mixture after adding Benedict’s solution in order to get the valid results? (1mark) ………………………………………………………………………………………………..……
b) What final color would the solution change to? (1mark) ……………………………………………………………………………………………..………
c) If you added iodine instead of Benedict’s solution to the mixture of saliva and starch, what colour would the solution have? (1mark)

………………………………………………………………………………………………………6.A patient complained of frequent thirst. A sample of the patient’s urine was found not to have any sugar.

(a)Name the hormone the person was deficient of. (1mark)

………………………………………………………………………………………

(b)Name the gland that secretes the above hormone. (1mark)

………………………………………………………………………………………

State the advantage of desert animals excreting their nitrogenous waste in form of urea and not ammonia. (1mark)

……………………………………………………………………………………………………………………………………………………………………………………………………………

In an investigation, the pancreatic duct of a mammal was blocked. It was found that the blood sugar regulation remained normal while, food digestion was impaired. Explain these observations. (2 marks)

……………………………………………………………………………………………………..………………………………………………………………………………………………………

Explain why glucose does not appear in urine of a healthy person even though it is filtered in

the Bowman’s capsule of a mammal. (1mark)

Explain why Lamarck’s theory of evolution is not accepted by biologists today (1mark)

………………………………………………………………………………………………………………………………………………………………………………………………………………

Distinguish between survival of the fittest and struggle for existence (2marks)

The diagram below illustrates a U-tube whose arms are separated by a membrane that allows water molecules only to pass.
State how the levels of the liquids in the arms would be after several hours. (1mark)

Arm A ……………………………………………………………………………..

Arm B ………………………………………………………………………………

Explain the process taking place in the arms of the U-tube (3marks)

……………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

The equation below represents a physiological process that occur in plants.

6CO_{2 +}6H₂O C₆H₁₂O_{6 +}6O₂

Name two conditions necessary for the process to occur (2marks)

……………………………………………………………………………………………………………………………………………………………………………………………….

Identify two adaptations of the leaf for the process indicated by the equation above. (2marks)

……………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………….

(a)Explain the observation made on the shoot when a seedling is placed on a horizontal position (3marks)

………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

b)Black ants will always move to where there is sugar.name the response (1mark)

………………………………………………………………………………………………………

The diagram below shows a nerve cell. Study it and answer the question that follow.
Identify the type of neurone (1mark)

……………………………………………………………………………………………

Give reasons for your answer in 17 (a) above (1mark)

…………………………………………………………………………………………………………………………………………………………………………………………

c) On the diagram, Indicate the direction of flow of impulse (1mark)
The diagram below is simple illustration of central nervous system and nerve supply system to the arm. The parts A, B, C and D represents points of which he nervous system can be blocked.

Identify the part that is blocked when

The hand is withdrawn but no pain is felt (1mark)

………………………………………………………………………………………………………

The pain is felt and the hand is withdrawn (1mark)

………………………………………………………………………………………………………

The pain is felt but the hand cannot be withdrawn (1mark)

………………………………………………………………………………………………………

The pain is not felt but the hand can be withdrawn at will (1mark)

………………………………………………………………………………………………………

Explain how knowledge of genetics can be applied in blood grouping and transfusion. (2marks)

The table below is a representation of a chromatid 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

Name the type of chromosomal mutation represented (1mark)

………………………………………………………………………………………………………

Name one mutagenic agent (1mark)

………………………………………………………………………………………………………

19.A certain species of a flowering plant has 23 chromosomes in the somatic cells. State and explain the number of chromosomes present in the endosperm nucleus. (2marks)

The diagram below represents a stage in cell division. Study it and answer the questions that follow

Identify the stage of cell division shown in the diagram above (1mark)

………………………………………………………………………………………………………

Give a reason for your answer in 22 (a) above (1mark)

………………………………………………………………………………………………………

The diagram below illustrates a mature embryo sac.
Name the structures labelled: (2marks)
……………………………………………………………………………………………………………………………
B…………………………………………………………………………………………………………………………….
What does structure C to transform after fertilization(1mark)

……………………………………………………………………………………………………..

Explain why pregnancy is not lost after the first trimester even if the ovaries are removed .

(3marks)

Identify two adaptations of a gaseous exchange surface (2marks)

(a) Identify the function following parts of a microscope (2marks)

(i)Diaphragm

(ii)Condenser

(b)Explain the term resolution as used in microscopy (1mark)

Name two supportive tissues in plants that are lignified (2marks)

……………………………………………………………………………………………………………………………………………………………………………………………………………..

The diagram below represents nitrogen circulation in an ecosystem.

(a) Identify the following organisms (3marks)

A ……………………………………………………………………………..

B ……………………………………………………………………………..

(b) Name process E

……………………………………………………………………………………………….

(a) Name the type of muscles found in the gut. (1mark)

………………………………………………………………………………………………………

(b) Give one difference between the muscles above and the one found in the heart (1mark)

State two methods of preventing malaria. (2marks)

………………………………………………………………………………………………………

……………………………………………………………………………………………………..

A process that occurs in plants is represented by the equation below.

C₆H₁₂O₆ 2C₂H₅OH + 2CO₂ + Energy

(a) Name the process. (1mark)

………………………………………………………………………………………………………

(b) State the economic importance of this process. (1mark)

……………………………………………………………………………………………………

State any two rules of binomial nomenclature. (2marks) ………………………………………………………………………………………………………

(a) Name the causative agents of the following human diseases (2 marks)

(i) Bilharzia…………………………………………………………………………………………

(ii)Amoebic Dysentery……………………………………………………………………………

(b) State three methods of controlling air pollution (3 marks)

……………………………………………………………………………………………………………………………………………………………………………………………………………………….…………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………