Answer all the questions.

1. State the importance of each of the following living organisms:
   
   1. nutrition (1 mark)
      
      
   2. excretion (1 mark)
      
      
2. 1. What is meant by the term seed dormancy? (1 mark)
      
      
   2. State three causes of seed dormancy. (3 marks)
      
      
      
3. State two functions of the placenta in mammals. (2 marks)
   
   
4. The diagram below illustrates a growing pollen tube.
   
   
   
   
   1. Name the part labelled B. (1 mark)
      
      
   2. Explain the role of the parts labelled A. (2 marks)
      
      
5. The diagram below shows a set up for an experiment to demonstrate a certan physiological process.
   
   
   
   
   1. What nature of solution is represented by 20% sugar solution? (1 mark)
      
      
   2. Explain the observation made on the set up after one hour. (2 marks)
      
      
6. State three roles of auxins in a plant stem. (3 marks)
   
   
7. A student drew a 6cm long diagram of a plant flower. If the actual length of the flower was 12cm, calculate the magnification of the drawing made by the student. Show your working. (2 marks)
   
   
8. Differenciate between phenotype and genotype as used in genetics. (1 marks)
   
   
9. State two functions of intervertebral discs in the mammalian skeleton. (2 marks)
   
   
10. 1. Explain two roles of diffusion in human beings. (4 marks)
       
       
    2. What is meant by each of the following terms?
       
       1. Crenated cell (1 mark)
       2. Flaccid cell (1 mark)
          
          
11. State three differences between tactic and tropic responses. (3 marks)
    
    
12. The diagram below represents a model used to demonstrate breathing in mammals.
    
    
    
    
    1. Name the mammalian structure represented by the parts labelled D and E.
       1. D ( 1 mark)
       2. E (1 mark)
          
          
    2. State the observation made when the string is pulled downwards. (1 mark)
       
       
    3. Explain the observation in (b) above. (2 marks)
       
       
13. State one function of each of the following parts of the mammalian eye:
    1. eye lashes (1 mark)
       
       
    2. lachrymal glands (1 mark)
       
       
14. State three structural differences between DNA and RNA. ( 3 marks)
    
    
15. 1. Which type of mammalian muscles is voluntary. (1 mark)
       
       
    2. Distnguish between tendon and ligament. (1 mark)
       
       
16. The diagram below illustrates a nerve cell.
    
    
    
    
    1. Name the type of nerve cell illustrated. (1 mark)
       
       
    2. Give a reason for your answer in (a) above. (1 mark)
       
       
    3. Identify the part labelled J. (1 mark)
       
       
    4. State one function of each of the parts labelled G and H.
       1. G (1 mark)
       2. H (1 mark)
          
          
17. Give a reason why the image is not formed when light is focused on the blind spot. (1 mark)
    
    
18. Explain why
    1. mammalian testes are located to hang outside the body. (2 marks)
       
       
    2. four months after fertilisation, ovaries can be removed from a huma n female, without terminating pregnancy. (2 marks)
       
       
19. Why is a burning charcoal stove in a poofy ventilated room likely to cause death of the inhabitants? (3 marks)
    
    
20. State one function of each of the following cell organelle:
    1. golgi bodies (1 mark)
    2. lysosomes (1 mark)
       
       
21. Name the type of skeleton that amkes up each of the following animals:
    1. locust (1 mark)
       
       
    2. bird (1 mark)
       
       
22. 1. Name two vestigial structures in human beings. (2 marks)
       
       
    2. Why are some bacteria unable to resist the effect of antibiotics? (2 marks)
       
       
23. Below is an illustration of a cross section of a plant root showing the transportation of substances in the plant.
    
    
    
    
    1. Name the substances transported along the parts labelled K and L.
       K (1 mark)
       L (1 mark)
       
       
    2. Give a reason for your answer in L above. (1 mark)
       
       
24. The diagram below shows the transportation of substances in a human body.
    
    
    
    Name the substances represented by
    M (1 mark)
    N (1 mark)
    P (1 mark)
    
    
25. State two roles of luteinising hormone in human reproduction. (2 marks)
    
    
26. The table provided shows the concentration of sodium and iodine in sea water and cell sap of plant.
    
    
    
    
    1. 1. Name the process through which plant cells take up sodium ions. (1 mark)
       2. Give a reason for your answer in (a) (i) above. (1 mark)
          
          
    2. If the plant was sprayed with with a chemical that inhibits respiration:
       1. which of the two ions uptake will be affected? (1 mark)
       2. give a reason for your answer in (b) (i) above. (1 mark)
          
          
27. The diagram below shows the gaseous exchange system of a locust.
    
    
    
    
    1. Name the structure labelled Q. (1 mark)
       
       
    2. State the function of the part labelled R. ( 1 mark)
       
       
    3. How is the part labelled S structurally adapted to its function? (2 marks)