Explain double fertilization in plants.

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 Double fertilization is a complex fertilization mechanism that has evolved in flowering plants, known as angiosperms. This process involves the joining of a female gametophyte (embryo sac) with two male gametes (sperm). It begins when a pollen grain adheres to the stigma of thecarpel, the female reproductive structure of a flower. After a pollen grain has landed on an accessible stigma, the pollen grain takes in moisture and begins to germinate, forming a pollen tube that extends down toward the ovary through the style. The tip of the pollen tube then enters the ovary and penetrates through the micropyle. The micropyle is an opening in the protective layers of the ovule. The pollen tube proceeds to release the two sperm in or near the embryo sac.

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 plz make my thumb up

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 incomplete. who will tell after it

then one of the male gamete fuses with the ovum or the egg and form seed.

the second moves upward and their fuses wih the polar nuclei to form the endospremic cell which later develops into endosperm.

polar nuclei: Two haploid nuclei in the centre of the embryo sac of flowering plants. These nuclei fuse with a male gamete nucleus to form a triploid endosperm nucleus, which subsequently divides to form the endosperm.

another short and good defination:

double fertilization: A process, unique to flowering plants, in which two male gamete nuclei, which have travelled down the pollen tube, separately fuse with different female nuclei in the embryo sac. The first male nucleus fuses with the egg cell to form the zygote; the second male nucleus fuses with the two polar nuclei to form a triploid nucleus that develops into the endosperm.

hope this helps. plz give thumbs up.

  • 98

i think we can make it a bit more simple like this

in flowering plants the fertilization is called double fertilization bcoz fertilization occurs twice. on entering the ovary the pollen tube releases 2 male gametes .in the first reaction , one of the male gametes fuses with eggcell and forms the zygote . this reaction is a diploid reaction and is also called syngamy.

in the second reaction  the second male gamete fuses with the 2 polar nuclei and form the product called P.E.N - primary endosperm nucleus. this reaction is called the triploid reaction or the triple fission.

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its triple fusion and not fission. fission is breaking of a bigger particle into 2 or more sub particles. and fusion is the joining of lighter or smaller particles to form larger particles.

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Double fertilization in flowering plants involves the fusion of two sperm cell nuclei of the male gametophyte with two cell nuclei of female gametophyte. One sperm fuses with the haploid egg cell to form the zygote; the other sperm unites with the diploid central cell to form a triploid cell that will develop to an endosperm.

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it takes two fusion- 1. fusion of male gamete to female gamete. 2. fusion of polar nuclei to male gamete. Thats why it is called Double fertilisation.

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The fusion of male gamete (pollen grain) with the egg cell is known to be syngamy. At the same time the fusion of another male gamete with bipolar nuclei is triple fusion.as fertilization is taking place two times it is said to be double fertilization
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Double fertilisation refers to the process in angiosperms (flowering plants) during reproduction, in which two sperm nuclei from each pollen tube fertilise two cells in an ovary. The pollen grain adheres to the stigma of the carpel (female reproductive structure) and grows a pollen tube that penetrates the ovum through a tiny pore called a micropyle. Two sperm cells (derived from the generative nucleus) are released into the ovary through this tube. One of the two sperm cells fertilises the egg cell (at the end of the ovary), forming a diploid (2n) zygote. The other sperm cell fuses with two haploid polar nuclei (contained in the central cell) in the centre of the embryo sac (or ovule). The resulting cell is triploid (3n). This triploid cell divides through mitosis and forms the endosperm, a nutrient-rich tissue inside the fruit. 

The two central cell maternal nuclei (polar nuclei) that contribute to the endosperm arise by mitosis from a single meiotic product. Therefore, maternal contribution to the genetic constitution of the triploid endosperm is different from that of the embryo. 

Recently research has shown that in one primitive group of flowering plants, the water lilies, Nuphar, the endosperm is diploid, resulting from the fusion of a pollen nucleus with one, rather than two, maternal nuclei. 

In gymnosperms, such as conifers, the food storage tissue is part of the female gametophyte only, a haploid (1n) tissue, so there is no double fertilisation.
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