Question

The amount of DNA in a mammalian cell in early prophase is ‘X’. What is the amount of DNA in the same cell in anaphase I of meiosis?
A. X/4
B. X/2
C. X
D. 2X

Answer 1

Hint:Meiosis occurs in germ cells to produce haploid gametes. After the meiotic division in cells, the number of chromosomes becomes half.
During meiosis cell division takes place two times and 4 cells are produced. These are called M-1 and M-2.

Complete answer:
During meiosis Meiosis-1 and meiosis-2 occurs. DNA replication occurs only one time before meiosis-1. During s phase, DNA is replicated and its amount becomes double.
After the S phase, meiosis-1 occurs and it has 4 phases that are prophase-1, metaphase-1, anaphase-1, and telophase-1.
So the amount of DNA is doubled during prophase-1. As it is given is the question that in early prophase-1 of a mammalian cell DNA amount is X. so this amount X is also the doubled amount of DNA.
The prophase-1 of meiosis is very complex and for a long time. During this phase, homologous chromosomes are paired, and crossing over takes place between homologous chromosomes.
During metaphase-1 paired chromosomes are aligned at the metaphase plate. During anaphase, these paired homologous chromosomes are separated.
During telophase-1 cytokinesis takes place and two daughter cells are made.
So in anaphase-1, the cell has not yet divided and the DNA amount is the same as it was in prophase-1 that is ‘X’. After telophase-1 when the cell is divided DNA is also divided equally into daughter cells.

So, the correct option is C. X.

Note: During meiosis-1 homologous chromosomes are separated and during meiosis-2 sister, chromatids are separated.
Due to crossing over variation occurs in daughter cells. Crossing over is also called gene exchange and it only occurs during meiosis, not during mitosis. So because of meiosis in germ new characters are developed.