Question

Which one of the following is not a characteristic of meiosis?
A. It involves two-stage of DNA replication one before meiosis-I and the other before meiosis-II
B. It involves recombination and crossing-over
C. Sister chromatids separate during Anaphase- I
D. Nuclear membrane disappears during Prophase

Answer 1

Hint: Meiosis is a type of cell division, in which a parent cell divides into four daughter cells, with each of them having half the chromosome number than the parent cell. This type of cell division happens in the division of gametes. The process is essential for maintaining the chromosome number stable over generations.

Complete answer: The stage of DNA replication occurs, but not in meiosis. It occurs in the S or synthesis phase of the cell cycle. There are two stages of meiosis, meiosis- I and meiosis- II, wherein both the phases cytokinesis and karyokinesis occur, which is cell division and nuclear division respectively. Here, the chromosome number gets halved. The stage between two meiosis does not involve the process of DNA replication and the phase is known as Interkinesis. Thus, statement A is incorrect.
Considering the other given statements:
-Recombination and crossing over are the two processes that result in genetic differences. And it occurs during Prophase I of meiosis. The process occurs in sex cells.
-Anaphase is the second stage of meiosis. During this process, the homologous chromosomes are pulled apart to the poles of the nucleus, at this stage the sister chromatids of these chromosomes remain attached.
-Prophase is the first stage of meiosis, where the nuclear membrane starts dissolving and disappears, and the chromosomes get condensed and the nucleolus disappears. It is the way by which the cells get prepared for the division.
Thus, the correct answer is Option A, since DNA replication occurs in the S phase of the cell cycle and not in meiosis.

Note: The different steps involved in the process of meiosis in the right order are Prophase, Metaphase, Anaphase, and Telophase. After the final step that is Telophase is over, the nuclear membrane gets reformed and two daughter nuclei get produced.