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1.Explain why it is necessary for plants to have their leaves spread out (2mks)

To provide a large surface for absorption of sunlight to maximize photosynthesis

3.State two ways in which herbaceous plants obtain their mechanical support (2mks)

Cell turgidity/Turgor pressure due to absorption of water keeps cells firm hence hold herbaceous plants upright

Use of tendrils Use of collenchyma

4(a) Name the proteinous substance that makes the exoskeleton of members of the phylum Arthropda (1mk)

chitin

(b) state two functions of the exoskeleton (2 marks)

Provides a large surface area for attachment of muscles

Protect internal tissues and organs of arthropods

c. state one disadvantage of exoskeleton to members of the phylum arthropda

Inhibits growth

5. explain how each of the following factors adapt the fish to movement in water

(a) swim bladder

- help fish to stay afloat in water by maintaining bouyancy.

(b) head

Fish has inflexible head that enables it to maintain a steady forward thrust

9. State the difference between glycolysis and Krebs’s cycle based on the following

Krebs cycle involve the oxidation of pyruvic acid into carbon dioxide and water whereas glycolysis involve the convertion of glucose to 2 molecules of pyruvic acid

(a) where they occur

Krebs cycle occur in the matrix of the mitochondrion whereas glycolysis occurs in the cytoplasm of a cell

(b) amount of energy produced

More energy is produced in the Krebs cycle compared to glycolysis

10 (a) Distinguish between gaseous exchange and respiration

Gaseous exchange is diffusion of diffusion of respiratory gases across the respiratory surface

Respiration is process by which cells break down of sugar by use of oxygen to produce energy , Carbon(IV)Oxide and water

(b)explain the importance of algae in a pond

Blue-green algae photosynthesize therefore producing oxygen and food for the aquatic organisms

11. state two advantages of an insect undergoing complete metamorphosis process (2mks)

Eliminates competition between the larvae and adult insects since they occupy different ecological niches

Increases their chances of survival

13. (a) state two reasons why the snake is classified as a reptile (2mks)

They lay eggs

Their bodies are covered with scales

(b) Name the structure which enables paramecium to move

Cilia

15 (a) state two activities that take place in the ovule of a flowering plant during fertilization

(b) state two functions of the seminal fluid in reproduction

(c)name the hormone that stimulates the contraction of muscles of the uterine wall during birth

Oxytocin

16 (a) Giving an example in each case, state the difference between internal and external fertilization (2mks)

External fertilization takes place outside the body

Internal fertilization takes place inside the body

(b) state the agent of pollination in maize plant (1mk)

Wind

17. Identify the response and the receptor from the following list of sensory structures and processes:

• Salivary gland

• Smell of fried eggs

• Olfactory cells

• Salivation

(a) Response

Salivation

(b) Receptor

Olfactory cells

18 explain how the knowledge of apical dominance is applied in agriculture (2 marks)

It increases yield in vegetative crops e.g tea and vegetables as removal of the apical bud allows the sprouting of many lateral buds

The knowledge of that apical dominance is caused by auxins is applied in promoting growth of roots in cuttings by applying auxins on the cuttings e.g cassava

19 (a) explain why the population of people with sickle cell anaemia is higher in malaria-prone areas (2marks)

Sickle cell anaemia offers a survival advantage against malaria

b.Explain why it is not advisable to put a patient on drip of distilled water for rehydration

Blood cells will burst as it will absorb the hypotonic distilled water through osmosis

22. State one function of the following parts of mammalian movable joints:

(i) Synovial membrane

Makes synovial fluid

(ii) Ligaments

Connective tissues that help in connecting two bones at the joint

24. Explain the difference between basal metabolic rate (BMR) between a 55-year-old man and a 8-year-old grandson (3mks)

The 8-year-old will have a higher BMR as he has many cells undergoing mitotic division to enable greowth hence uses more energy