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प्रश्न
Explain the events upto double fertilisation after the pollen tube enters one of the synergids in an ovule of an angiosperm.
उत्तर
The events which occur during double fertilization are:
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Two male gametes are released by the pollen tube into the cytoplasm of synergid.
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One of these male gametes moves towards the egg cell and fuses with the nucleus. This process is called syngamy and results in the formation of a diploid cell, zygote,which eventually forms an embryo.
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The other male gamete moves towards the polar nuclei located in the central cell and fuses with them to form a triploid primary endosperm nucleus (PEN). This process is called triple fusion.
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Since two types of fusion, syngamy and triple fusion, take place here, the phenomenon is called double fertilisation.
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संबंधित प्रश्न
Name the parts of an angiosperm flower in which development of male and female gametophyte take place.
Read the statement and answer the questions that follow.
A flower of brinjal has 520 ovules in its ovary. However, it produces a fruit with only 480 viable seeds.
(a) What could have prevented the rest of the 40 ovules from maturing into viable seeds? Explain giving a reason.
(b) Describe the development of a dicot embryo in a viable seed.
(c) Why certain angiospermic seed albuminous while others are exalbuminous? Explain.
Give an example of an angiosperm seed that has a perisperm. Name the part the perisperm develops from.
Define Racemose inflorescence
Name a plant which flowers every twelve years.
Give a reason for the Following:
Pollen grains of wind-pollinated flowers are produced in large quantities.
Sketch and label ‘structure of a pea flower’.
Fragrant flowers with well developed nectaries are an adaptation for ______.
Pollen grains are well preserved as fossils because of the presence of ______
In a fertilized ovule, n, 2n, and 3n conditions occur respectively in ______
