CHAPTER 8: ENDANGERED ECOSYSTEM 1

LEARNING AREA : ENDANGERED ECOSYSTEM

Question 1 : GUIDED QUESTION PAPER 3

A group of student set up an experiment to study the water pollution level in three water

samples.The materials have been used as shown in Figure 1. The time taken for the

methylene blue solution to turn colorless is shown in Table 1.

Water

sample

Time taken for discoloration

(minutes)

X 60

Y 45

Z 120

Table 1

Figure 1

a. What is the meaning of biochemical oxygen demand (BOD)?(1m)

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b. Based on the result in Table 1, what conclusion can you draw about

i. the concentration of dissolved oxygen in samples Y and Z?(1m)

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ii. the pollution levels of samples Y and Z?(1m)

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CHAPTER 8: ENDANGERED ECOSYSTEM 2

c. Based on the result given, explain why the rate of discoloration is higher in

sample Y.(2m)

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d. Give two precautions which should be taken in this experiment.(2m)

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e. Based on Figure 1, state the following variables (3m)

i. manipulated : _____________________________________________________

ii. responding : _____________________________________________________

iii. constant

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f. State the hypothesis for the experiment.(3m)

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CHAPTER 8: ENDANGERED ECOSYSTEM 3

QUESTION 2

Figure 2 below shows a phenomenon on the earth in which changes in layer P of the

atmosphere take place.

Figure 2

a. i. State layer P.(1m)

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ii. State the human activity that can cause an increase in the thickness of layer P.

(1m)

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b.i. Identify the phenomenon shown in Figure 2. (1m)

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iv. State two problems related to the phenomenon described.(2m)

a. _______________________________________________________

b. _______________________________________________________

c. State two steps to reduce the problem encountered because of the thickness

of layer P. (2m)

a. _______________________________________________________

b. _______________________________________________________

CHAPTER 8: ENDANGERED ECOSYSTEM 4

QUESTION 3

Figure 3 shows the situation at Y site that is developing.

Figure 3

a. Explain the purpose of development.(2m)

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b. State the effects of following to our ecosystem (3m)

i. Factories: _________________________________________________

ii. Vehicles: __________________________________________________

iii. Deforestation: ______________________________________________

c. Predict the effect to ecosystem if there is no proper management of development

activities.(2m)

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CHAPTER 8: ENDANGERED ECOSYSTEM 5

d. If you are the city planner, describe one way how you can develop certain places

very well and at the same time sustain the quality of environment. (2m)

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e. Explain two steps that can be taken by ourselves to preserve our environment

based on the activities in Figure 3. (2m)

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CHAPTER 8: ENDANGERED ECOSYSTEM 6

QUESTION 4

Figure 4 shows the sources of emission of three types of pollutant gases.

Figure 4

a. Based on Figure 4 above, state the major source of carbon monoxide, oxides of

nitrogen and sulphur dioxide. (3m)

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b. Explain the effect of carbon monoxide on human beings. (2m)

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c. Suggest two ways to reduce the emission of sulphur dioxide. (2m)

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d. Both sulphur dioxide and oxides of nitrogen can cause acid rain. Explain how acid

rain is formed. (3m)

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CHAPTER 8: ENDANGERED ECOSYSTEM 7

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e. What are the effects of acid rain on plants and soil? (4m)

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QUESTION 5

Figure 5 shows the location of ozone layer at stratosphere, at about 20 – 50 km from the

earth surface.

Figure 5

a. i. What is ozone layer? (1m)

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ii. State the function of ozone layer. (1m)

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UV rays

Ozone layer

Stratosphere

Troposphere

Earth

CHAPTER 8: ENDANGERED ECOSYSTEM 8

b. The thinning of ozone layer has been recorded by scientists since the

1970s.

i. State the main cause of ozone depletion.(1m)

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ii. How does the cause that you stated in (b) i deplete the ozone layer.

(3m)

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c. State two effects of ozone depletion. (2m)

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d. Explain two steps to reduce ozone depletion. (2m)

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CHAPTER 8: ENDANGERED ECOSYSTEM 9

QUESTION 6 : SHORT ESSAY

Diagram below shows a phenomenon which happens in the earth’s temperature.

State the phenomenon and explain the effect of the phenomenon on the

environment if the concentration levels of carbon dioxide are getting higher.

(3marks)

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Earth

atmosphere

CO2CO2

SOLAR RADIATIO

CO2

Stratosphere

Troposphere

CHAPTER 8: ENDANGERED ECOSYSTEM 10

CHAPTER 8: ENDANGERED ECOSYSTEM 11