SPM BIology 2015


9 . Diagram 9.1 shows leguminous plants which are planted in between young rubber trees to assist the growth of the rubber tree.
Rajah 9.1 menunjukkan tumbuhan kekacang yang ditanam di antara anak-anak pokok getah untuk membantu pertumbuhan pokok-pokok getah itu.Cher Questions Solution Bank Rumusan Jawapan SPM & IGCSE Questions Answers Solution


(a) Explain how the leguminous plants assist the growth of the young rubber trees.
Terangkan bagaimana tumbuhan kekacang membantu pertumbuhan anak-anak pokok getah itu.


(b) Diagram 9.2 shows concentration of carbon dioxide in the atmosphere which is increasing since 1750.

Rajah 9.2 menunjukkan kepekatan karbon dioksida atmosfera yang meningkat sejak tahun 1750.

(i) Explain the causes which contribute to the increasing concentration of carbon dioxide in the atmosphere and the effects of the environment.

Terangkan sebab-sebab yang menyumbang kepada peningkatan kepekatan karbon dioksida dalam atmosfera dan kesan-kesannya ke atas alam sekitar.

(ii) Suggest ways should be taken to balance the concentration of carbon dioxide in the atmosphere.

Cadangan cara-cara yang perlu diambil untul mengimbangi kepekatan karbon doiksida dalam atmosfera.

Cher Questions Solution Bank Rumusan Jawapan SPM & IGCSE Questions Answers Solution

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Answer ( 1 )

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    9.a) -There are nitrogen-fixing bacteria (Rhizobium) found on the root nodules of leguminous plants.

    -These bacteria increase fertility of the soil and allow the rubber trees to grow bigger faster.

    -Via the process of nitrogen-fixation, these bacteria can convert atmospheric nitrogen into ammonium compounds like nitrate ions.

    -These nitrate ions can then be absorbed by the rubber tree roots.

    -Nitrate is an important macronutrient as it is used in the production of proteins, chlorophyll and enzymes needed during photosynthesis.

    -As the roots of these leguminous plants decompose, they leave behind ammonium  compounds which can be converted into nitrate and be absorbed through the soil.

    -These leguminous plants also play an important role as cover crops, preventing the growth of weeds which take up space and steals nutrients or water from the rubber trees.


    b)i) -Increasing concentrations of carbon dioxide (CO2) can be due to deforestation and excessive logging.

    -We lose Earth’s carbon sinks and without trees, there would be less photosynthesis and less conversion of CO2 into oxygen (O2).

    -Furthermore, burning of fossil fuels in factories causes an increase in atmospheric C02.

    -Open burning also releases a lot of CO2 into the atmosphere.

    -An increasing amount of CO2 leads to the greenhouse effect, heat gets trapped within the atmosphere and the Earth’s overall average temperature increases causing global warming to occur.

    -Global warming then leads to the melting of ice caps and rising sea levels.

    ii)-Replace fossil fuels with a renewable energy source.

    -Enforce the law, ban illegal logging activities and set up high fines.

    -Educate on the 3R principles, teach the public and students to reuse and recycle papers.

    -Set up more forest reserves to preserve our rainforests.

    -Make use of technology which captures CO2 from the atmosphere.

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