Question

What is the site of meiosis in organisms?

Answer 1

Hint: The division which occurs in a diploid cell and gives rise to four haploid cells or nuclei, each having half the number of chromosomes in comparison to the parent cell is termed as meiosis.
The division was first studied by Beneden in 1887, Strasburger in 1888, Sutton in 1900, Winiwarter in 1900 in different organisms and the term ‘meiosis’ was first introduced by Farmer and Moore in 1905.

Complete answer:
In diploid organisms meiosis occurs during the formation of spores or gametes while in haploid organisms it occurs during the germination of zygote. The cells in which meiosis occurs are called meiocytes. In animals spermatocytes and oocytes while in plants microsporocytes and megasporocytes.
Meiosis is similar in all plants and animals. Depending upon the stage when meiosis occurs, the latter is of three types –
In most animals and plants meiosis takes place during the formation of gametes (gametogenesis). Such meiosis is termed as gametic or terminal meiosis. When two gametes fuse in fertilization, the diploid zygote is formed and results in a diplontic life cycle.
In some lower plants such as fungi, protists, algae) meiosis takes place in the zygote and resulting organisms are haploid. It is termed as zygotic or initial meiosis and shows haplontic life cycle.
In most of the plants (such as pteridophytes, gymnosperms and angiosperms) meiosis occurs at the time of sporogenesis. It is called as sporic or intermediate meiosis and showed diplohaplontic life cycle because of the presence of diploid and haploid multicellular phases.

Note-
The essential stages that take place during meiosis are-
Two successive divisions without any DNA replication between them.
Formation of chiasmata and crossing over.
Segregation of homologous chromosomes.
Separation of sister chromatids.