QUESTIONS

1. What is meant by the following terms?
   
   1. Niche (1mark)
   2. Ecology (1mark)
2. What changes would occur to a marine amoeba species if it was transferred into a fresh water pond? (2marks)
3.      
   1. State one function of cilia in organisms. (1mark)
   2. Name two parts of the human body which have cilia. (2marks)
4. In an experiment, it was found that when maggots were exposed to light, they moved to dark areas.
   
   1. Name the type of response exhibited by the maggots.(1mark)
   2. What is the survival values of the response in (a) above to the maggots? (1mark)
5. How is the alveolus of a mammal adapted for gaseous exchange? (3marks)
6.    
   1. What are vestigial structures? (1mark)
   2. State one major importance of convergent evolution to living organisms. (1mark)
   3. Why is Lamarck’s theory not popular with scientist? (1mark)
7. Explain the meaning of the following terms (1mark)
   
   1. Phenotype
   2. Test cross (1mark)
8. State the role of intervertebral discs (1mark)
9. State the adaptations of the following parts of the eye to its function.
   
   1. Choroid (2marks)
   2. Retina (2marks)
10. A flower was found to have the following characteristics
    
    • Inconspicuous petals
    • Long feathery stigma
    • Small light pollen grains
      
      1. What is the likely agent of pollination of the flower? (1 mark)
      2. What is the significance of the long feathery stigma in the flower (1mark)
11.    
    1. A student visiting a game park observed an adult elephant flapping its ears twice as much as its calf in order to cool its body when it is hot. Explain (2marks)
    2. Explain why some desert animals excrete uric acid rather than ammonia. (2marks)
12. The diagram below represents the pathway of water from soil into the plant.
    
    
    1. Name the structures labeled K and L
    2. Name the process by which mineral salts enter into the plant (1mark)
13.    
    1. How is support attained in herbaceous plants? (3marks)
    2. Name two tissues which are thickened with lignin. (2marks)
14. The diagram below shows the difference in growth response to varying hormone concentration by root and shoot.
    
    What is the effect of increasing auxin concentration on:
    
    1. Roots (1mark)
    2. Shoot (1mark)
15. The diagram below represents a stage during cell division
    
    
    1.    
       1. Identify the stage of cell division (1 mark)
       2. Give two reasons for your answer in (a) (i) above (2 marks)
    2. Name the structures labeled M (1mark)
16. State one function of revolving nose piece in light microscope(1marks)
17. Construct a step in a dichotomous key using two animals one with two pairs of legs and the other with four pairs of legs. (2marks)
18. Explain how the following factors determine the daily energy requirement in human:
    
    1. Age (1 mark)
    2. Occupation (1 mark)
19. Explain how drooping of leaves on a hot sunny day is advantageous to plant. (2marks)
20. Name the organism that;
    
    1. Causes malaria. (1mark)
    2. Transmits malaria. (1mark)
21. State the two major components of the nervous system. (2marks)
22. The diagram below represents a neurone
    
    
    1.    
       1. Name the neurone. (1mark)
       2. Name the parts labelled P and Q. (2marks)
    2. State the function of the sensory nerve endings. (1mark)
23. Give four principles used in binomial nomenclature. (4marks)
24. Name the structures that occur in plant cells but not in animal cells. (2marks)
25. The diagram below show the structure of an organelle that is found in most cells.
    
    
    1. Name the organelle. (1mark)
    2. What is the main function of the organelle? (1mark)
    3. What is the importance of the infoldings in the inner membrane? (1mark)
    4. List the membrane that a molecule must pass through as it moves from the external medium matrix of the organelle. (2marks)
    5. Give two examples of the cells where you would expect to find many organelles. (2marks)
26.    
    1. Name the products of the light reaction in photosynthesis. (2marks)
    2. Explain why insectivorous plants such as Drosera species trap and digest nitrogenous compounds. (2marks)
27. An individual is of blood group B Positive;
    
    1. Name the antigens in individual's blood. (1mark)
    2. Give the reason why the individual cannot receive blood from group A donor. (1mark)
28.       
    1. Name the type of respiration that is most efficient. (1mark)
    2. Give reasons for your answer in (a) above. (1mark)
    3. Explain why short distance runners breathe quickly and deeply at the end of a race. (2marks)

MARKING SCHEME

1.    
   1. Niche - The place (habitat) where the organism lives and its function in the habitat; (1mark)
   2. Ecology - The study of the inter-relationships between organisms and their environment; (1mark)
2. Water would be drawn into the amoeba cell by osmosis;
   Contractile vacuoles would form (more frequently) to discharge the excess water; (2marks)
3.    
   1. Used for movement/expelling unwanted particles; (1mark)
   2. Trachea or tracheal epithelium; Oviduct; Inner ear (Max..2marks)
4.    
   1. Negative photo taxis; (1marks)
   2. Enables them to escape harmful stimuli such as excess heat which dehydration; enables them to seek favorable habitats and escape predators (max.1mark)
5. Moist to dissolve respiratory gases; thin epithelium for faster diffusion/shorter diffusion distance; Vascularised to transport respiratory gases; (3marks)
6.    
   1. These are organs/structures that are reduced in size and have ceased to function in an organism; (1mark)
   2. Enables organisms to develop (adaptation) analogous structures of similar structures in completely unrelated groups of organisms to exploit similar environments; (1mark)
   3. It lays emphasis on acquired characteristics which cannot be inherited; (1mark)
7.    
   1. Phenotype
      Is the observable characteristics of an organism as influenced by genes ; (1mark)
   2. Test cross
      The cross used to determine whether an individual exhibiting dominant traits is homozygous or heterozygous by crossing it with a homozygous recessive individual for that particular trait; (1mark)
8. Acts as a cushion that absorbs shock and reduces friction; Makes vertebral columns flexible by allowing for a certain degree of movement between the vertebrae; (2marks)
9.    
   1. Choroid
      It has pigmented cells that gives the eye a dark colour and prevents reflection on light in the eye; has numerous blood vessels that supply nutrients to the eye; (max.2marks)
   2. Retina
      It is transparent; contains rods and cones that perceive light ;( Max.2marks)
10.    
    1. Wind; (1mark)
    2. To enable it trap pollen grains in the air; (1mark)
11.    
    1. Calf has large surface area to volume ratio than the adult; hence calf loose more heat than the adult ; (or accept…converse) (2marks)
    2. Elimination of uric acid requires less water than ammonia, hence (more) water is conserved;
       Uric acid is less toxic than ammonia hence safer to excrete where there is less water; (2marks)
12.    
    1. K - Root hair (1mark)
       L - Xylem vessel (1mark)
    2. Active transport/diffusion. (1mark)
13.    
    1. The roots of herbaceous plants absorb water which eventually get into cells by osmosis;
       The cells after taking in water, become turgid; this turgidity of the cells provides support to the plant; (3marks)
    2. Xylem vessels; Sclerenchyma tissue; (2marks)
14.    
    1. Roots – inhibit growth; (1mark)
    2. Short – promotes faster growth; (1mark)
15.    
    1.      
       1. Anaphase 1(1mark)
       2. Homologous chromosomes separates at the equator;
          Chromosomes start migrating to opposite poles; Sister chromatids attached at the centromere; (Max...3marks)
    2. Spindle fibres (1mark)
16. It provide platform where objective lens is attached;
    It revolve to make objective lens click in position for viewing to be done; (Max..1mark)
17.      
    1. Animal with two pairs of legs .. go to 2;
    2. Animal with four pairs of legs .. go to ..; (2marks)
18.    
    1. Young people are actively/ rapidly growing hence require more energy than older people
       NB: growth has to be mentioned (1mark)
    2. Manual workers require more energy than secretary workers (1mark)
19. The leaves exposed a smaller surface area to the sun; thus reducing transpiration/Excessive water loss; (2marks)
20.      
    1. Plasmodium (1mark)
    2. Female Anopheles mosquito (1mark)
21. Central nervous system
    Peripheral nervous system (2marks)
22.    
    1. Sensory neurone (1mark)
    2. P-myelin sheath/neurilemma (1mark)
       Q-synaptic knob (1mark)
    3. To perceive stimulus and convert it into nerve impulse (1mark)
23.      
    • Organisms named using genus and species
    • The names are latinized
    • The names are written in italics
    • Genus (4marks)
24. Cell wall
    Chloroplast (2marks)
25.      
    1. Mitochondrion ( reject mitochondria) (1mark)
    2. Generate energy in the form of Adenosine Triphosphate (ATP) (1mark)
    3. They create a large surface area for attachment of respiratory enzymes (1mark)
    4. Cell membrane, outer membrane, and inner membrane. (marked as a whole…..2marks)
    5. cardiac muscle
       skeletal muscle
       sperm cell (2marks)
26.      
    1. ATP,
       Hydrogen ions,
       Oxygen (Max ….2marks)
    2. They grow in nitrate deficient soils hence trap and digest insects to obtain nitrogenous compounds (marked as a whole….2marks)
27.      
    1. Antigen B and Antigen D (2marks)
    2. The antibody a in the blood plasma of the recipient would react with the donor antigen A causing agglutination. (1mark)
28.    
    1. Aerobic respiration (1mark)
    2. There is complete oxidation of the substrate to carbon (IV) oxide and water. (1mark)
    3. To increase supply of oxygen required for complete oxidation of the accumulated lactic acid into water and carbon (IV) Oxide (2marks)