a. Explain briefly the importance of the following factors and organisms in the nitrogen cycle
    (i)  lightning;    [3  marks]
    (ii)  Nitrosomonas; [2  marks]
    (iii)  Azotobacter.    [2  marks]

b. Name the excretory organ in:
    (i)  insects: [1  mark]
    (ii)  earthworm.

c. Define
    (i)  hepatitis;  [4  marks]
    (ii)  kidney stones    [4marks]

d.     (i) State three effects of lack of sense  receptors in the skin to humans.  [3 marks]
    (ii) List three layers of the epidermis in the skin of humans.    [3 marks]

e.    (i) What  is metamorphosis?  [2  marks]
    (ii) State the type of metamorphosis  exhibited by each of the following insects  listed in the table below.

Insect	Type of metamorphosis
Grasshopper
Cockroach
Butterfly
Mosquito
Housefly