Form 4 2025.
(Ecology)
1. Which disease could be prevented by
(1mark)
a) Personal hygiene?
b) Efficient sewage disposal?
c) Purification of drinking water?
2. It is possible to contract amoebic
dysentery as a result of close contact with
an infected person. Similar contact with
malaria victim cannot produce infection.
Explain why the transmission of these two
diseases is so different. (2marks)
3. List four modes of expressing food
relationships in an ecological system, then
describe the nature and importance of
energy in such relationships. (5marks)
4. Name two hosts which form the
biological environment for each of the
following (3marks)
a) Tapeworm (Taenia Solium)
b) Malaria parasite (Plasmodium spp)
c) Schistosoma spp
5. State two reasons why biological
control is preferred to chemical control in
the control of pests and parasites
(2marks)
6. State the possible application of the
following plant hormones in agriculture.
(6marks)
(i) Auxins
(ii) Gibberellins.
7. ) Give two advantages of
metamorphosis in insects (2 marks)
(b)Name the hormone responsible for
metamorphosis in insects (1 mark)
8. Name the meristematic tissues responsible
for:
(a) Primary growth (1mark)
(b) Secondary growth in plants (1mark)
9. When the tip of a plant is cut, lateral
branches develop.
a) What name is given to this phenomenon?
(1 mark) b) Which plant hormone is
responsible for the phenomenon above (1
mark)
10. Name two hosts which form the biological
environment for each of the following
(3marks)
a) tapeworm
b) malaria parasite
c) Schistosoma spp
11. differentiate between pyramid of numbers
and pyramid of biomass (2marks)
12. State two characteristics of a pyramid of
numbers(2marks)
13. the following table shows the estimated
number of organisms recorded in a dam.
Organism Number
Small fish 3500
Microscopic algae 120000
Crocodiles 95
Large fish 950
Mosquito larvae 8900
a) Draw a possible food chain for the dam
(1 mark)
b) Draw a suitable pyramid of numbers for
the ecosystem in the dam (2marks)
14. describe how capture-recapture method
can be used to study the population of beetles
in an area (10marks)
15. apart from mere observation of actual
feeding, suggest three methods that can be
used to determine the food eaten by
animals(3marks)
