Question

The correct sequence of the sub stages of prophase 1 is
A) Diakinesis, pachytene, diplotene, zygotene, leptotene
B) Leptotene, zygotene, pachytene, diplotene, diakinesis
C) Pachytene, zygotene, leptotene, diplotene, diakinesis
D) Leptotene, zygotene, diplotene, diakinesis, pachytene

Answer 1

Diploid cell division is of two types: Mitosis and Meiosis. In mitosis, there are two daughter cells formed, both with the same diploid chromosome number, and one cycle of DNA duplication and cell division. In Meiosis, there are four haploid daughter cells after one cycle of DNA duplication and two cycles of cell division.

Complete answer:
Prophase 1 occurs in Meiosis1. In this stage, the pairs of homologous chromosomes align together, and crossing over of genetic material takes place so that the daughter chromosomes are no longer identical to the parent. The four stages are leptotene where the chromosomes align and prepare for recombination; zygotene during which crossing over takes place between the chromatids in the tetrad; pachytene in which these chromosomes now start to separate; diplotene, in which the chiasmata break down, and the pairs move apart, and finally diakinesis where they are at opposite poles of the cell.

The order of prophase 1 is leptotene, zygotene, pachytene, diplotene, and diakinesis. The correct answer is option B
Options A, C, and D show the wrong sequence of events for prophase 1, and are incorrect.
Meiosis occurs in eukaryotic cells, allowing the halving of the chromosome number to form the haploid gametes, which on fusing will reform a diploid zygote.

Hence the correct answer is option ‘B’.

Note: In eukaryotic cells most of the organism’s cells will undergo mitotic cell division and remain diploid. Formation of haploid gametes occurs in the germ cells, as part of the process of reproduction. In the human body, this takes place in the ovaries and testes.