SPM Biology 2013


9 . Diagram 9.1 shows an ecosystem.

Rajah 9.1 menunjukkan suatu ekosistem.

(a) Many new factories are built nearby the river. Explain the bad effects of the presence of the factories to the ecosystem.

Banyak kilang baharu didirikan berdekatan dengan sungai. Terangkan jesan buruk kewujudan kilang-kilang tersebut terhadap ekosistem ituCher Questions Solution Bank Rumusan Jawapan SPM & IGCSE Questions Answers Solution

(b)(i) Explain the importance of maintaining the river as a habitat in the ecosystem.
Terangkan kepentingan mengekalkan sungai sebagai satu habitat dalam ekosistem itu.

(ii) Describe ways to improve the water quality of the river for a better survival of aquatic organisms.

Huraikan cara-cara untuk menambahbaik kualiti air sungai untuk kemandirian organisma akuatik yang lebih baik.

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Answer ( 1 )


    9.a) Water pollution, Air pollution

    -Factories may release harmful chemical substances (effluents) into the river. These may be toxic/poisonous towards the aquatic life. Thus, when organisms consume the contaminated water, it may result in death.

    -The food chain may get disrupted if a particular food source for a consumer rapidly decreases.

    -Toxic substances such as heavy metals get consumed and can accumulate within the food chain.

    -Factories that burn fossil fuels release a lot of carbon dioxide into the atmosphere. This causes the greenhouse effect and heat gets trapped within the atmosphere, increasing Earth’s overall average temperature and causing global warming.

    -Factories also release sulphur dioxide (SO2) and oxides of nitrogen (NO and NO2) into the atmosphere through the combustion of fossil fuels.

    -SO2 and oxides of nitrogen combine with water vapour in the air, forming sulphuric acid and nitric acid. This causes the occurrence of acid rain.

    -Acid rain causes water pollution, contaminates drinking water.

    -Furthermore, it increase the acidity of soil causing death to plants within the vegetable farm.


    b)i)-The river is a habitat for many aquatic organisms.

    -These organisms are also a food source for consumers.

    -If this habitat is not maintained, the food source is lost and the food web gets disrupted.

    -Example, the river has fish which is a food source for eagles, without the river, the eagles lose their food source and their numbers might greatly decrease.

    -Furthermore, it is a source of water for many organisms in the ecosystem, thus is has to be maintained.


    ii) -To improve water quality factories should treat their waste before dumping it into the river so it doesn’t become harmful for the aquatic organisms.

    -Furthermore, the community can volunteer to help clean up the river.

    -By collecting and removing large pieces of trash.

    -Factories in the area can use scrubbers which clean up their emissions to prevent the occurrence of acid rain.

    -Farming lands nearby should stop the use of excessive fertilizer. This helps prevent eutrophication and algal bloom from occurring.

    -Enforcement of law by prohibiting the dumping of garbage and waste into the river.

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