SPM BIology 2015


5 . Diagram 5.1 shows the longitudinal section of reproductive organ of a plant.

Rajah 5.1 menunjukkan keratan memanjang organ pembiakan bagi suatu tumbuhan.

(a)(i) Based on Diagram 5.1, explain how X is formed.

Berdasarkan Rajah 5.1, terangkan bagaimana X terbentuk.

(ii) Explain what happens to the plant if structure X is failed to form.

Terangkan apa yang berlaku kepada tumbuhan itu jika struktur X gagal terbentuk.

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(b) Diagram 5.2 shows two types of fruits. The fruits have different number of seeds. Explain why.

Rajah 5.2 menunjukkan dua jenis buah-buahan. Buah-buahan itu mempunyai bilangan biji yang berbeza. Terangkan mengapa.

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(c) Diagram 5.3 shows a growth curve of a germinating seed of a plant.
Diagram 5.3 menunjukkan lengkung pertumbuhan bagi biji benih tumbuhan yang sedang bercambah.

(i) Explain one difference between the growth rate of the plant at stages X and Y.

Terangkan satu perbezaan antara kadar pertumbuhan itu pada peringkat X dan peringkat Y.

(ii) The plant undergoes secondary growth. Explain the importance of secondary growth.

Tumbuhan itu mengalami pertumbuhan sekunder. Terangkan kepentingan pertumbuhan sekunder.

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Answer ( 1 )


    5.a)i)X-pollen tube.

    -Formed via pollination- anther releases pollen grains which are transferred onto the stigma.

    -Fertilization process is initiated.

    -A sugar solution is secreted by the stigma. Pollen grain starts to germinate and the pollen tube forms.

    ii)-Without the pollen tube, the male nuclei would not reach the ovule and double fertilization would not occur.

    -There wouldn’t be formation of seeds or fruit.


    b)-The number of seeds reflects on the number of ovules a plant has within its ovary.

    for the 2nd mark explain, the number of seeds each of the fruits have.

    -Within the ovary of the mango, there is only one ovule thus resulting in only one seed.

    -The watermelon has many ovules thus it has many seeds.


    c)i)-During stage X, the dry mass decreases as the food stored within the seed is used to provide energy for germination.

    -During stage Y, plant growth rate increases indicated with an increase in dry mass- photosynthesis occurs. -Growth follows a sigmoid curve.


    ii)-During secondary growth, diameter of the plant’s stem increases- this provides mechanical support to the plant

    -For more water, minerals and nutrient transport- secondary growth, there is an increase in secondary phloem and xylem tissue.

    -Secondary xylem(wood) is produced, this is to ensure that the plant stem is strong.

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