9.4.1 Human Activities that Endangered an Ecosystem (Structured Question 1 & 2)


Question 1:
(a) Diagram I shows the effects of farming activities near a pond.


Explain how the farming activities cause the death of the aquatic plants and the fishes in the pond.
(b) Diagram II shows a new industrial area situated near a residential area.


Discuss the good and the bad effects caused by the industrial activities on human and environment in years to come.




Answer:
(a)
– Farmers use fertilisers that usually contain nitrates and phosphates.
– Fertilisers which contain nitrates/ phosphates may leach into the pond when it rains.
– Algae in the lake grow faster.
– They may grow so much that they completely cover the water.
– Black out the light for plants growing beneath them.
– Photosynthesis rate is reduced.
– Dissolved oxygen also reduced.
– Plants on the top of the water and beneath the water eventually die.
– Their remains are a good source of food for bacteria.
– Bacteria decomposed the dead plant rapidly.
– The large population of bacteria respires, using up oxygen, so there is very little oxygen left for other living organisms.
– BOD increased.
– Water population increases.
– Those aquatic plants and fish which need oxygen die.

(b)
Advantages:
– More job opportunities
– More economic activities and development projects
– Attract tourists
– Improve infrastructure

Disadvantages:
– Can cause respiratory problems/ asthma/ bronchitis/ irritates the eye
– Crime rate increases

Environment:
– Industries emit poisonous gases such as sulphur dioxide/ oxides of nitrogen/ smoke/ fine solid particles
– Contribute to air pollution
– Oxides of nitrogen and Sulphur dioxide dissolve in rain water to form acid rain.
– Makes the soil acidic and unsuitable for the cultivation of crops
– Smoke and haze reduce light intensity reaching stomata and cause the rate of photosynthesis to decrease
– Which subsequently reduces crop yield
– Carbon dioxide leads to the greenhouse effect, resulting in an increase in the atmospheric temperature
– Cause the extinction of organisms


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