1 Four of the classes of vertebrates and five possible descriptions of these classes are shown
Draw a straight line to match each class of vertebrate to its description.
class of vertebrate description
body with naked skin, two
pairs of limbs
body with hair, two pairs
body with feathers, one
pair of wings
body with scales, with fins
body with scaly skin, two
pairs of limbs or no limbs
Match words, A, B, C and D, with the numbers 1ñ 4 on the drawing.
A contains light receptors
B contains receptors sensitive to some liquid chemicals
C contains sound receptors
D contains receptors sensitive to some gaseous chemicals
2 (a) Many communities treat their sewage and release non-polluting water into a local river.
What is meant by the term sewage?
(b) Sometimes the sewage treatment works cannot deal with all of the sewage and
untreated material is released into the river.
Suggest the likely effects of releasing untreated sewage into a river.
Match substances, A, B, C and D, with the numbers 1-4 in the table.
1 kills bacteria in the body
2 may lead to addiction to hard drugs
3 lowers the level of cholesterol in the blood
4 relieves some of the symptoms of the disease
(a) (i) Name an organism from this food web that is a
primary consumer 
tertiary (third level) consumer 
(ii) Using information only from Fig. 3.1, complete the food chain.
→ → → → leopard 
(b) Fig. 3.2 shows a pyramid of numbers for a food chain from this food web.
Which organism in the food web would occupy the 3rd trophic level in this pyramid of numbers? 
(c) In some years a plague of locusts occurs.
Predict and explain what could happen to the population of baboons when this occurs. 
Match structures, A, B, C and D, with the numbers 1ñ4 on the diagram.
C fertilised egg