1. The document discusses processes of succession and colonization in ecosystems. It describes how pioneer species are replaced over time by other species until a climax community is reached. 2. Several questions assess understanding of food webs and chains, energy transfer between trophic levels, and species interactions like predation, parasitism, and competition. 3. Control of rat populations in an oil palm plantation is discussed, including estimating rat numbers using mark-capture techniques and considering reasons for differences in rat populations between areas. Biological control using owls is proposed.

1. INTERVENTION-BIOLOGY CHAPTER 8
CHAPTER 8 : DYNAMIC ECOSYSTEM
1. The following information is related to a process that occurs in the ecosystem
1 The pioneer species is replaced by other species
2 The process occurs gradually over a period of time
3 The process ends with a climax community
What is the process?
A colonisation B competition C succession D evolution
Oil palm estate owners experienced huge losses due
to attacks from pests especially the rats.
2. From the information given above, suggest the most effective way to overcome the problem.
A Set up mouse traps C Increase the number of owls in the estate
B Poison the rats D Destroy the rat’s habitat
3. The diagram represents the flow of energy in a typical ecosystem.
5 4
3
2
1
Which two boxes represent carnivorous organisms?
A 1 and 2 C. 2 and 3
B 3 and 4 D. 4 and 5
Energy from sun
4. An insecticide was sprayed to kill the caterpillars. In which organisms would the highest level of
insecticide accumulate after a period of time?
A Deer C. rabbits
B Foxes D. pigeon
5. In the effort to estimate the population of rats in a paddy field, a farmer set up some traps and
managed to capture 22 rats. The farmer tagged the rats by putting a small metal ring on the rats’
feet and then released them. After 2 days, the farmer set up the trap again and this time he
managed to trap 20 rats. Among the trapped rats, 4 of them were found with the ring. What is the
estimated population of the rats in the paddy field?
A. 38 C. 110
B. 46 D. 168
6. Which of the following pairs of organism practises parasitism?
A Sea anemone and hermit crab C Barnacles and whale
light

2. B Ticks on a cat’s body D Green algae and fungi
7. The diagram shows the energy losses and gains of a rabbit.
Which of the following shows the percentage loss of heat?
% energy used for growth and repair % energy lost as heat
A 10 30
B 30 10
C 30 60
D 60 30
The diagram shows part of a food web for a fresh water pond.
8. Which organism is a primary consumer?
A Pond snails B Pond weed C Water beetles D Water mites
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3. 9. Which of the following show the changes of rabbit and fox population in an ecosystem?
A. C.
B. D.
10. The diagram shows the flow of energy in a typical ecosystem?
3
E
D
C
B
A

4. (a) Fill in the blanks.
Terms Represented
by Box
Definition
Producer A · Known as a……………………. as they produce
their own food
Consumer
· Herbivore
· Carnivore
· Omnivore
B,C, D · Known as h……………………. as they feed on
producers or other consumers
……….. · Feed on p…………………….. such as plants
Eg: Cattle
C · Feed on animals Eg : …………………..
………... · Feed on …………………. and ………………
Eg: crow
…………………. E
.
· Breaks down complex organic compounds into
simpler substance
· Eg: …………………… and ……………………
(b) Which box represents the trophic level which receives the least energy?
……………………………………………………
(c) Which box represents the largest total mass of living organisms?
……………………………………………………
(d) Which box represents the secondary consumers?
……………………………………………………...
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5. 11. The figure shows part of a food web.
Carnivorous Bird
Bird A Bird B Bird C Bird D Bird E
Small fish
Zooplankton Oysters Snails
Algae Garden Plants
(a) The sun is the ultimate source of energy of the food web. Name the process by which the
sun’s energy enters the ecosystem through the algae and leaves of garden plants.
…………………………………………………………………………………………………….
(b) (i) Name the biological relationship between birds D and E.
……………………………………………………………………………………………………
(ii) Describe and explain one possible effect on the population of bird D if there is a great
reduction in the population of bird E.
………………………………………………………………………………………………………
………………………………………………………………………………………………………
(c) What is the term used to describe the diet of the small fish and the snail
(i) small fish :……………………………… (ii) snail :………………………………………..
(d) (i) Name two groups of organisms that are not shown in the diagram but they are very
important to maintain the food web shown above.
1. ………………………………………… 2. ………………………………………………
(ii) How do they help to maintain the above ecosystem in a balanced state.
……………………………………………………………………………………………………
……………………………………………………………………………………………………
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6. (e) (i) Construct one food chain of five organisms which are shown in the above food web.
……………………………………………………………………………………………………
(ii) What does the arrows between organisms in a food chain indicate.
………………………………………………………………………………………………….
(iii) State two ways in which energy is lost along the food chain.
1. ……………………………………………………………………………………………
2. …………………………………………………………………………………………….
Colonisation and succession in Mangrove swamp
12. Figure below shows the geographical distribution of mangrove trees along the east
coast.
1
(a) (i) Name the mangrove trees in zone A to D.
A : ………………………… B : ……………………
C : ………………………… D : …………………… [4 marks]
(ii) Among the mangrove trees stated in (a) (i), which is the pioneer species?
……………………………………………………………………… [2 marks]
(b) State two problems faced by the pioneer species in the colonization of
swampy area.
.………………………………………………………………………………………………..
… ......................................................................................................................................
[2 marks ]
(c) Explain two adaptive characteristics that enable the pioneer species to survive in
the swamp area.
………………………………………………………………………………………………..…..
………………………………………………………………………………………. ……….. …
………………………………………………………………………………………...................
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A
C
E D B

7. …………………………………………………………………………………… [2 marks]
(d) (i) What is meant by viviparous seedlings?
…………………………………………………………………………………… [ 1 mark ]
(d) (ii) What is the benefit of this to the mangrove plant?
…………………………………………………………………………………………………….
…………………………………………………………………………………… [1 mark]
13. Figure above shows an oil palm estate. An oil palm estate is identified as a habitat for owls and
rats. The manager of oil palm estate plans to use biology control to control the population size of rats
which are damaging the oil palm in the estate.
Based on ecological studies, some students have carried out a study to estimate the size of the rats
population between the area of estate. The result obtained are recorded in Table 1
Steps in the collection of
samples
Station X Station Y
Number of rats captured,
markes and released
110
70
Number of rats recaptured 3
130 50
days later
Number of marked rats
60 25
(a) What technique is used for estimating the population of the rat?
………………………………………………………………………………..
1 mark]
(b) (i) Give two characteristics of the material used for marking the rat.
……………………………………………………………………………..
……………………………………………………………………………..
…………………………………………………………………………….
2 marks]
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8. ( b )(ii) Where will you release the rat after they are marked?
………………………………………………………………………………..
………………………………………………………………………………..
[1 mark]
(c) Why are the rat caught again after three days?
…………………………………………………………………………………
[1 mark]
(d) Estimate the population of the rat in station X and station Y.
………………………………………………………………………………………….
…………………..………………………………………………………………………
………………..……………………………………………………………………......
…………………….……………………………………………………………………
[2 marks]
(e) Give three reasons for the difference in the population of the rat in two stations.
………………………………………………….…………..
……………………………………………………………………………………………………..
…………………………………………………………………………………………………….
…………………………………………………………………………………….…
[3 marks]
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