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STD 12 - 1. sexual reproduction in flowering plants — NEET STD 11 Science — Question

Gujarat BoardEnglish MediumSTD 11 ScienceNEETSTD 12 - 1. sexual reproduction in flowering plants4 Marks
MCQ
Which one of the following statements is wrong?
  • ✓
    When pollen is shed at two­celled stage, double fertilization does not take place.
  • B
    Vegetative cell is larger than generative cell.
  • C
    Pollen grains in some plants remain viable for months.
  • D
    Intine is made up of cellulose and pectin.
✓

Answer

Correct option: A.
When pollen is shed at two­celled stage, double fertilization does not take place.
a
(a) : In $60\%$ of flowering plants, the pollen grains are shed at two­ celled stage (tube cell + generative cell). Further, development of male gametophyte (pollen grain) occurs on stigma. Pollen grain gives rise to pollen tube which absorbs nourishment from the cells of style for its growth. Generative cell divides to give rise to two male gametes. Out of these, one fuses with the egg to form diploid zygote (generative fertilization or syngamy) whereas the second male gamete fuses with the two haploid polar nuclei or diploid secondary nucleus of the central cell to form primary endosperm nucleus (vegetative fertilization or triple fusion). These two acts of fertilization occur in the same embryo sac and are referred to as double fertilization.

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