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Ananya Shree

Class 12th
Biology
1 year ago

Trace the events that would take place in flower from the time of Pollen grain of species fall on stigma up To completion of fertilization.

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Muskan Anand

1 year ago

Germination of Pollen Grains on Stigma  The pollen grains absorb fluid present on stigma and swell up. The exine ruptures at the place of germ pore and intine come out in the form of a tube with its internal contents. This small tubular structure is called a pollen tube and the process is called pollen germination. ii) Entry of pollen tube into Ovule: - The entry of pollen tube into ovule happens by the micropyle or chalaza or also by oblique sides of the ovule. Only 1 pollen tube begins inside the embryo sac of an ovule. Usually, two synergids are eliminated by the entry of a pollen tube into the embryo sac.   iii) Discharge of Mate Gametes:- Both male gametes are discharged into the embryo sac after entering the pollen tube, either by generating two pores in the pollen tube and releasing each male gamete through each pore or by the pollen tube rupturing and releasing the male gametes into the embryo sac. (4) Development of Embryo:- The zygote divides by mitosis into a pro-embryo first. After development outcomes in production of heart and globular shaped embryo and also that will eventually mature into an embryo of shapes of a horseshoe with one or more than one cotyledons.  In a dicot embryo, the part of the embryonal axis about the level of addition is called epicotyl and it eliminates into plumule while a portion of the embryonal axis under the level of attachment is known as hypocotyl and it terminates into the radicle.

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