Question

List any two significance of meiosis

Answer 1

The term meiosis was coined by J.B.Farmer in 1905. Meiosis produces a total of four haploid cells from each original diploid cell.

Complete answer:
Meiosis superficially resembles two mitotic divisions without an intervening period of DNA replication. There are two types of meiotic division. In the first meiotic division the reduction of chromosome number takes place and thus two haploid cells are resulted by this division. First meiotic division is also known as the heterotypic division. In the second meiotic division, haploid cells divide mitotically and result into four haploid cells. The second meiotic division is also known as homotypic division. In the homotypic division pairing of chromosomes, exchange of genetic material and reduction of the chromosome number do not occur.
Both the meiotic divisions occur through four usual stages of the meiosis, Viz., Prophase, metaphase, anaphase and telophase. The prophase of the first meiotic division is Very significant because the most cytogenetical events such as crossing over, synapsis, etc., Occur during this phase.
Meiosis has the greatest significance for the biological world. Some of them are
i) The meiosis maintains a definite and constant number of the chromosome in the organism. When gametes are formed by meiosis, the number of chromosomes are halved. So, each gamete will have one pair of chromosomes. Later the haploid gamete Fuse with the complementary haploid gamete and form diploid zygote (2n). Hence, the number of chromosomes are maintained.
ii) By crossing over ( the exchange of genes between homologous chromosomes, resulting in a mixture of parental characteristics in offspring). The meiosis provides an opportunity for the exchange of the genes and thus causes the genetic variations among the species. The variations are the raw material of the evolutionary process.

Notes: The meiosis is required to run the reproductive cycle of plants and animals. Meiosis occurs in the germ cell of sexually reproducing organisms.