Question : Explain the process of fertilization in plants.

1.	Question : Explain the process of fertilization in plants.
Answer» Solution :(1) Fertilisation is the process of fusion of make male and female gametes. (2) For the fusion ofmale and female gametes pollen grains have to reach the surface of the stigma. This is CALLED pollination. (3) Pollen grain received by the stigma germinate and give rise to pollen tubes. Only one pollen tube finally reaches the embryosac. (4) This tube will have two male nuclei, which migrate to the tip of the pollen tube at the time of fertilization. (5) Usally the pollen tube enters the ovule through micropyle and discharge the two male gemtes into this embryosac. (6) One male nucleus (gamete) approaches the egg and fuses with it to form a diploid (2n) zygote. this is FIRST fertilisation. ` n oversetuarr O + n underset +O rarr2n ("zygote")` (7) The other male nucleus (gamete) reaches the secondary nucleus (2n) and fuses with it to form endosperm nucleus which will be TRIPLOID. this is second fertilization in the embryosac. `n overset uarr O+2n underset +O RARR 3n (P.E.N)` (8) Thus double fertilisation occurs in embryosac which is unique in flowering plants.

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