Question

Describe the stages of embryosac formation in angiosperm with suitable diagram.

Answer 1

The angiosperm consists of male and female parts.

The male parts include anther and filament. The long stalk part is filament and upper broad portion is called anther. Anther contains pollen grain. The female parts include upper broad portion called stigma. The middle thin portion called style and the lower portion called ovary. Ovary contains ovule. And ovule contains egg and two pollar nuclei.

The pollen grain/male gamates on reaching stigma release a liquid substance. The stigma absorb that liquid substance and form Pollen tube. This pollen tube grows larger and larger and then ultimately reach the ovule. The two male gamates travel through Pollen tube towards ovule. When one male gamate fuse with egg then it forms zygote and when the other male gamate fuse with two polar nuclei then it forms triploid primary endosperm nucleus. As the fusion occurs two times then it is known as DOUBLE FERTILIZATION.

After that the zygote develops into a embryo and the triploid primary endosperm nucleus into endosperm which provide nourishment to the growing embryo.

And then the ovule develop into seed and ovary fruit.


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