Youtor
Life Cycle Of Angiosperms
>> YOUR LINK HERE: ___ http://youtube.com/watch?v=wrS2FTjqRZ0
The flower of the sporophyte produces microspores that form male gametophytes and megaspores that form female gametophytes. • The male gametophytes are in the pollen grains, which develop within microsporangia in the anthers. Each male gametophyte has two haploid cells: a generative cell that divides, forming two sperm, and a tube cell that produces a pollen tube. Each ovule, which develops in the ovary, contains a female gametophyte, also known as an embryo sac. The embryo sac consists of only a few cells, one of which is the egg. • After its release from the anther, the pollen is carried to the sticky stigma at the tip of a carpel. Although some flowers self-pollinate, most have mechanisms that ensure crosspollination, which in angiosperms is the transfer of pollen from an anther of a flower on one plant to the stigma of a flower on another plant of the same species. • After reaching the ovary, the pollen tube penetrates through the micropyle, a pore in the integuments of the ovule, and discharges two sperm cells into the female gametophyte (embryo sac). One sperm fertilizes the egg, forming a diploid zygote. The other sperm fuses with the two nuclei in the large central cell of the female gametophyte, producing a triploid cell (3n). This type of double fertilization, in which one fertilization event produces a zygote and the other produces a triploid cell, is unique to angiosperms. • After double fertilization, the ovule matures into a seed. The triploid central cell of the female gametophyte develops into endosperm, tissue rich in starch and other food reserves that nourish the developing embryo. • #angiosperms #angiospermLifeCycle
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