KNEC KCSE BIOLOGY TOPICAL QUESTIONS AND ANSWERS

Below is a diagram of a poorly planned town showing some building and facilities

8/1/2023

Comments

Below is a diagram of a poorly planned town showing some building and facilities

a) Giving evidence from the diagram, state two likely sources of water pollution. (2mks)

Industrial effluents because the factory is close to the river.
Domestic effluents since some houses are next to the river and the marsh.

b) State three ways that the positioning of the refuse pit and sewage works pose danger to the residence of the town. (3mks)

Drinking water contamination since the water works is close to the sewage works;
Spread of diseases to residents nearby because many pathogens and diseases vectors are found in the sewage works and refuse pit near the houses;
Air pollution because the prevailing wind carries unpleasant smell over the town;

c) Residents living close to the marsh are likely to suffer from malaria. Explain. (1mk)

The swamp is the breeding site for mosquito larva hence adult mosquitos may spread malaria to residents living nearby.

d) Suggest two control measures to overcome water pollution in the area. (2mks)

Treating industrial and domestic effluents before releases it into the water.
Cooling the water from the factories to avoid raising water temperature in the river and swamp.
Carry out environmental impact assessment before establishing factories/industries;etc

Comments

The diagram below represents a maize seedling.

8/1/2023

Comments

The diagram below represents a maize seedling.

a) Name the structure labeled A and C (2mks)

A – Coleoptile
B – Remaining of seed / seed.

b) State the functions of parts labeled A, B and C. (3mks)

A - Protects the delicate plumule as it pushes through the soil during germination.
B – Contains stored food which is hydrolyzed and used by the germinating seed / seedling before the seedling starts to photosynthesize.
C
– Anchors the seedling.
- Absorbs water and mineral ions.

c) Name the type of germination exhibited by maize (1mk)

Hypogeal germination

d) Name two conditions necessary for seed germination other than water and oxygen. (1mk)

Optimum temperature / warmth.
Growth hormones.
Viability of seed
Enzymes

e) What is the role of oxygen in seed germination? (1mk)

It oxidizes the stored food in the seed to give energy for growth/synthesis of new materials;

Comments

The diagram below represents the direction of flow of blood in a gill capillary. The percentage of oxygen in solution at position A, B, P, Q and R is given in the table below.

8/1/2023

Comments

The diagram below represents the direction of flow of blood in a gill capillary. The percentage of oxygen in solution at position A, B, P, Q and R is given in the table below.

a) Why is the oxygen percentage low at P? (1mk)

Blood coming from the body has supplied the tissue cells with oxygen/ oxygen has diffused out of capillary into the tissue fluid;

b) Using evidence from the data given, suggest what will happen to oxygen in the water at point B. (3mks)

Oxygen concentration at B reduces/will be at lowest; because blood at P has a lower oxygen concertation creating a diffusing gradient; From A to B there is a diffusion gradient hence at B much oxygen has diffused into the from water into the blood;

c) Name the organ into which blood coming from the capillary at Q flows. (1mk)

Heart

d) Suppose the flow of blood in the capillary illustrated above was in the opposite direction, explain the disadvantage it would have to the fish. (2mks)

Amount of exchange of respiratory gasses between blood and water would reduce; because of reduced diffusion gradient;

e) Name the principle where the blood flows in the opposite direction to another fluid. (1mk)

Counter flow system.

Comments

Below is a diagram of a poorly planned town showing some building and facilities

Below is a diagram of a poorly planned town showing some building and facilities

a) Giving evidence from the diagram, state two likely sources of water pollution. (2mks)

b) State three ways that the positioning of the refuse pit and sewage works pose danger to the residence of the town. (3mks)

c) Residents living close to the marsh are likely to suffer from malaria. Explain. (1mk)

d) Suggest two control measures to overcome water pollution in the area. (2mks)

The diagram below represents a maize seedling.

The diagram below represents a maize seedling.

a) Name the structure labeled A and C (2mks)

b) State the functions of parts labeled A, B and C. (3mks)

c) Name the type of germination exhibited by maize (1mk)

d) Name two conditions necessary for seed germination other than water and oxygen. (1mk)

e) What is the role of oxygen in seed germination? (1mk)

The diagram below represents the direction of flow of blood in a gill capillary. The percentage of oxygen in solution at position A, B, P, Q and R is given in the table below.

The diagram below represents the direction of flow of blood in a gill capillary. The percentage of oxygen in solution at position A, B, P, Q and R is given in the table below.

a) Why is the oxygen percentage low at P? (1mk)

b) Using evidence from the data given, suggest what will happen to oxygen in the water at point B. (3mks)

c) Name the organ into which blood coming from the capillary at Q flows. (1mk)

d) Suppose the flow of blood in the capillary illustrated above was in the opposite direction, explain the disadvantage it would have to the fish. (2mks)

e) Name the principle where the blood flows in the opposite direction to another fluid. (1mk)

TOPICS

Form 2

Form 3

Form 4

Archives

Categories

Below is a diagram of a poorly planned town showing some building and facilities

​Below is a diagram of a poorly planned town showing some building and facilities

​a) Giving evidence from the diagram, state two likely sources of water pollution. (2mks)

​b) State three ways that the positioning of the refuse pit and sewage works pose danger to the residence of the town. (3mks)

​c) Residents living close to the marsh are likely to suffer from malaria. Explain. (1mk)

​d) Suggest two control measures to overcome water pollution in the area. (2mks)

The diagram below represents a maize seedling.

​The diagram below represents a maize seedling.

​a) Name the structure labeled A and C (2mks)

b) State the functions of parts labeled A, B and C. (3mks)

​c) Name the type of germination exhibited by maize (1mk)

​d) Name two conditions necessary for seed germination other than water and oxygen. (1mk)

​e) What is the role of oxygen in seed germination? (1mk)

The diagram below represents the direction of flow of blood in a gill capillary. The percentage of oxygen in solution at position A, B, P, Q and R is given in the table below.

​The diagram below represents the direction of flow of blood in a gill capillary. The percentage of oxygen in solution at position A, B, P, Q and R is given in the table below.

​a) Why is the oxygen percentage low at P? (1mk)

​b) Using evidence from the data given, suggest what will happen to oxygen in the water at point B. (3mks)

​c) Name the organ into which blood coming from the capillary at Q flows. (1mk)

​d) Suppose the flow of blood in the capillary illustrated above was in the opposite direction, explain the disadvantage it would have to the fish. (2mks)

​e) Name the principle where the blood flows in the opposite direction to another fluid. (1mk)

TOPICS

Form 2

Form 3

Form 4

Archives

Categories

Below is a diagram of a poorly planned town showing some building and facilities

a) Giving evidence from the diagram, state two likely sources of water pollution. (2mks)

b) State three ways that the positioning of the refuse pit and sewage works pose danger to the residence of the town. (3mks)

c) Residents living close to the marsh are likely to suffer from malaria. Explain. (1mk)

d) Suggest two control measures to overcome water pollution in the area. (2mks)

The diagram below represents a maize seedling.

a) Name the structure labeled A and C (2mks)

c) Name the type of germination exhibited by maize (1mk)

d) Name two conditions necessary for seed germination other than water and oxygen. (1mk)

e) What is the role of oxygen in seed germination? (1mk)

The diagram below represents the direction of flow of blood in a gill capillary. The percentage of oxygen in solution at position A, B, P, Q and R is given in the table below.

a) Why is the oxygen percentage low at P? (1mk)

b) Using evidence from the data given, suggest what will happen to oxygen in the water at point B. (3mks)

c) Name the organ into which blood coming from the capillary at Q flows. (1mk)

d) Suppose the flow of blood in the capillary illustrated above was in the opposite direction, explain the disadvantage it would have to the fish. (2mks)

e) Name the principle where the blood flows in the opposite direction to another fluid. (1mk)