Sexual Reproduction in Flowering Plants Test - 8

The process of formation of female gametophyte inside the ovary by meiotic and mitotic division is called megasporogenesis.

Anther produces pollen grains by the process of meiosis in which four microspores are produced by single microspore mother cell. The number of chromosome reduces to half.

Microsporangium is covered by a number of layers. The outer layer or integuments surround the tepetum. The tepetum provide nutrients to growing microspores that leads to pollen grains.

Pollen grain is covered by two layers. The outer layer is called exine, made up of tough material. The inner layer is intine. There is a small opening in exine layer through which pollen grain germinate to form pollen tube.

Alternation of generation is the cyclic change in organisms involving haploid and diploid stages. Meiotic division results into haploid stage and fusion of haploid gametes results into diploid stage.

Ovule is surrounded by parenchymatous tissues called nucellus. Nucellus is diploid cells as it do not undergoes reduction division.

Angiospermic embryo sac is 8-nucleate but 7-celled at maturity. This includes 3- celled egg Synergids, 3 antipodal cells and 2 polar nuclei.

Ovule/s are located inside the ovary. The point of attachment of ovule to ovary is called funicle. Funicle extends to helium as stalk.

The female gametophyte in angiosperms is called Embryo sac. It contains egg apparatus, antipodal cells and polar nuclei. After fertilisation embryo sac changes into seed.

In ovule female gamete is formed at micropylar end and three antipodal cells at chalazal end. The two central nuclei are called polar bodies that fuse with one of male gamete to form endosperm.