5.
Which of the following statements is incorrect about meiosis?
a. Two rounds of DNA replication occur
b. The chromosome number is reduced to half
c. Four daughter cells are formed
d. Homologous chromosomes are paired

Incorrect Statement About Meiosis: CSIR NET Life Sciences MCQ Solved

The incorrect statement about meiosis is option a. Two rounds of DNA replication occur. Meiosis features only one DNA replication event before two cell divisions, distinguishing it from mitosis. This reductional division produces haploid gametes essential for sexual reproduction.​

Option Analysis

• a. Two rounds of DNA replication occur: Incorrect. DNA replicates once during interphase S phase prior to meiosis I; no replication occurs between meiosis I and II, ensuring chromosome halving.​

• b. The chromosome number is reduced to half: Correct. Meiosis I separates homologous chromosomes, yielding haploid cells from diploid parent.​

• c. Four daughter cells are formed: Correct. Two divisions (meiosis I and II) produce four haploid gametes.​

• d. Homologous chromosomes are paired: Correct. Synapsis in prophase I pairs homologs, enabling crossing over for genetic diversity.​

Meiosis Process Overview

Meiosis begins with DNA replication in interphase, forming diploid cells with duplicated chromosomes. Meiosis I (reductional) includes prophase I (pairing, recombination), metaphase I (homolog alignment), anaphase I (homolog separation), and telophase I/cytokinesis, yielding two haploid cells. Meiosis II (equational) mirrors mitosis: sister chromatids separate, forming four haploid cells without further replication.​

Meiosis, a key topic in CSIR NET Life Sciences, involves reduction division for gamete formation. The incorrect statement about meiosis claiming “two rounds of DNA replication occur” misrepresents the process, as replication happens only once before two divisions. This ensures halving of chromosome number from diploid (2n) to haploid (n), vital for genetic stability in offspring.​

Why DNA Replication is Single in Meiosis

Unlike mitosis with replication per division, meiosis replicates DNA solely in pre-meiosis interphase. Post-meiosis I, cells enter meiosis II sans S phase, preventing chromosome doubling. This mechanism underpins options b, c, and d as accurate: chromosome halving, four haploid cells, and homologous pairing in prophase I.​

Exam-Relevant Comparisons

Mastering these distinctions boosts CSIR NET performance in cell biology sections.