Question

Meiosis involves
A. Two nuclear divisions and one chromosome division.
B. One nuclear division and one chromosome division.
C. Owo nuclear division and two chromosome divisions.
D. Two nuclear divisions and two chromosome divisions.

Answer 1

Meiosis is a special form of cell division of germ cells in sexually reproducing species used to create gametes, such as sperm or egg cells. It involves two divisions which ultimately result in four cells with only one copy of each paternal and maternal chromosome. These cells are our reproductive cells – male sperm, female eggs. There are eight stages in meiosis namely, Prophase I, Metaphase I, Anaphase I, Telophase I and cytokinesis, Prophase II, Metaphase II, Anaphase II and Telophase III and cytokinesis.

Complete answer:
Meiosis is a type of cell division in which the four haploid cells are developed from the diploid parent cell. There are two stages, meiosis I and meiosis II where in the nuclear division takes place twice. Chromosomes are split only in anaphase II of meiosis II. In meiosis I, there is a chromosomal division to the opposite pole, without splitting the centromere.

Thus, option (C) is the correct choice i.e, One nuclear division and two chromosome divisions.

Additional information:
- Cells divide and reproduce in two ways namely, mitosis and meiosis. Mitosis results in two alike daughter cells, while meiosis results with four reproductive cells.
- The aim of meiosis is to halve genetic material and to cut the number of cellular chromosomes by half, from 46 chromosomes to 23 chromosomes.
- In this way, as the egg and sperm cells merge during fertilisation, the developing embryo will receive the appropriate amount of special genetic material from each parent.
- Meiosis is important because it guarantees that all species created by sexual reproduction possess the correct number of chromosomes.
- Meiosis also creates genetic diversity by the recombination process.

Note: Meiosis occurs in two stages. Meiosis 1 and Meiosis 2. But in meiosis 1, two diploid daughter cells are produced by the separation of homologous chromosomes whereas in meiosis 2, four haploid daughter cells are produced by the separation of sister chromatids. Crossing over or genetic recombination occurs only in meiosis 1. Meiosis 2 is similar to mitotic cell division except that the cells that divide in meiosis have homologous chromosomes.