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Sexual Reproduction in Flowering Plants — BIOLOGY STD 12 Science — Question

Rajasthan BoardEnglish MediumSTD 12 ScienceBIOLOGYSexual Reproduction in Flowering Plants1 Mark
Question
For two statements are given-one labelled Assertion and the other labelled Reason. Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.
  1. Both assertion and reason are true, and reason is the correct explanation of assertion.
  2. Both assertion and reason are true, but reason is not the correct explanation of assertion.
  3. Assertion is true, but reason is false.
  4. Both assertion and reason are false.
Assertion: Double fertilization is unique to angiosperms.
Reason: Triple fusion occurs in both fertilization, i.e. first and second.
✓

Answer

  1. Assertion is true, but reason is false.

Explanation:

S.G. Nawaschin (1898) was the first to show that both the sperms released by a pollen tube are involved in fertilization. They fertilize two different elements of the embryo sac. The phenomenon is unique to angiosperms and is called double fertilization. The nucleus of one of the sperms fuses with the egg nucleus (syngamy) and that of the other migrates to the central cell where it fuses with two polar nuclei or their fusion product, the secondary nucleus. The second fertilization involves the fusion of three nuclei (sperm with two polar nuclei). This phenomenon is called triple fusion.

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