Another Trengganu Trial 2010 Essay Question ..Credit to the owner!
8(a) Diagram 8.1 shows the changes that occurs in a lake due to the human activities.
Based on the Diagram 8.1, explain how this activities cause the changes in a lake.
[10 marks]
ANSWER: F : The condition of the river is the result of eutrophication
P1: Farmers use fertilizers that usually contains nitrates/phosphate
P2: Fertilizer/animal waste/silage which contain nitrate/phosphate may washed out in water when it rains/leaching/run into the lake.
P3: Algae in the lake grow faster (when they are supplied with extra nitrate/(phosphate)
P4: (they may grow so much) that they completely cover the water.
P5: Block out the light for plants growing beneath them.
P6: Photosynthesis rate reduced
P7: Dissolve oxygen also reduced
P8: Plant on the top of water and beneath water eventually die.
P9: Their remains are good source of food bacteria //bacteria decomposed the dead plant rapidly//bacteria breed rapidly
P10: The large population of bacteria respires, using up oxygen,so there is very little oxygen left for other living organism
P11: BOD increased
P12: Those fish/ aquatic animal which need oxygen move to other areas or die
Based on your knowledge in biology, explain the harmful effects of the activities to the mankind and their surrounding. Suggest ways to overcome this problem. [ 10 marks]Harmful effects to mankind and surrounding:
P1: Industries, factories, and vehicles contribute to air pollution
P2: Industries emit pollutants such as sulphur dioxide/ oxides of nitrogen smoke/fine solid particles
P3: Which can cause respiratory problems/asthma/bronchitis/Irritates the eye
P4: Oxides of nitrogen and sulphur dioxide dissolve in rain water to form acid rain
P5: Makes the soil acidic and unsuitable for the cultivation of crops
P6: Smoke and haze reduce light intensity cause the rate of photosynthetic decrease.
P7: Which subsequently reduces crop yield
P8: Carbon dioxide lead to green house effect, result in an increase in the atmosphere temperature
P9: Climatic change occur
P10: Hot water is discharged into nearby lakes and river lead thermal pollution
P11: Cause instant death/reduction of aquatic species
Any 6 points
Ways to overcome
P12: Implementation of law to reduce pollution
P13: use unleaded petrol/sewage treatment
P14: (Formal and informal) education stressing (on the concept of recycle, reuse, reduce and renew)
P15: Reduce the burning of fossil fuels
P16: Use alternative energy source/ using renewable energy(solar energy, hydroelectric and wind power)
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