Question

Assertion:
The first meiosis division is known as heterotypic division.
Reason:
The first division of meiosis results in a reduced number of chromosomes.

a. Both Assertion and Reason are correct and reason is the correct explanation for Assertion.
b. Both Assertion and Reason are correct but reason is not the correct explanation for Assertion.
c. Assertion is correct but Reason is incorrect.
d. Both Assertion and Reason are incorrect.

Answer 1

Sexual reproduction is very common among the animals. During fertilization, the germ cells pass through the different stages of cell division. Meiosis is a special type of cell division of the germ cell. There are two steps of meiosis which are meiosis I and meiosis II.

Complete answer:
Meiosis is a special type of cell division that occurs in the germ cells of sexually-reproducing organisms and it is used to produce the gametes, such as sperm or egg cells. There are two rounds of cell division that take place in the meiosis division and finally produce four cells with only one copy of each paternal and maternal chromosome.

Before entering into the stages of division, genetic material from the paternal and maternal copies of each chromosome is crossed over and forms new combinations on each chromosome. At the time of the fertilization, the haploid cells generated by meiosis from a male and female will fuse to produce a cell with two copies of each chromosome again in the zygote.

The whole process of meiosis cell division is divided into 2 stages and further each stage is subdivided into several phases. The phases of meiosis I are prophase I, metaphase I, anaphase I, and telophase I. The phases of meiosis II are prophase II, metaphase II, anaphase II, and telophase II.

Meiosis I is known as the reduction division because during meiosis I, the number of chromosomes is reduced to half and two haploid cells are produced after meiosis I. But meiosis II is the equational division. During this division, the number of chromosomes remains the same as in the daughter cells produced after meiosis I. After meiosis II, a total of four haploid cells are produced. In meiosis, the first division i.e. meiosis I is known as heterotypic division as the number of chromosomes is reduced by half during this division.

Hence, the correct answer is option (A).

Note: Meiosis is a type of cell division. This type of division is observed in the germ cells during fertilization in the sexually-reproducing organisms. This division occurs in two steps which are meiosis I and meiosis II. Meiosis I is a reduction division because of the number of chromosomes reduced to half in this division. This type of division is known as heterotypic division.