Q.7 A cell in G1 of interphase has 12 chromosomes. How many chromatids will be found per cell during metaphase II of meiosis?
- (A) 6
- (B) 12
- (C) 18
- (D) 24
A cell in G1 of interphase with 12 chromosomes reaches metaphase II of meiosis with 12 chromatids per cell. This SEO-optimized article answers the MCQ: A cell in G1 of interphase has 12 chromosomes. How many chromatids will be found per cell during metaphase II of meiosis? (A) 6, (B) 12, (C) 18, (D) 24—crucial for molecular biology and genetics students mastering cell division.
Correct Answer: Option (B) 12
In G1, the cell has 12 unreplicated chromosomes (2n=12). DNA replication in S phase creates 12 chromosomes, each with 2 chromatids (24 total chromatids).
Meiosis I separates homologous pairs, yielding two cells with 6 chromosomes each (still 2 chromatids per chromosome, 12 chromatids per cell). In metaphase II, each of these cells aligns 6 chromosomes (12 chromatids) at the equator, as sister chromatids remain joined until anaphase II.
Explanation of All Options
Chromosome and chromatid counts change predictably across meiosis stages.
-
(A) 6: Incorrect. This confuses chromosomes with chromatids; metaphase II has 6 chromosomes but 12 chromatids per cell.
-
(B) 12: Correct. Post-meiosis I reduction: haploid cells retain 2 chromatids per chromosome (6 chromosomes × 2 = 12 chromatids).
-
(C) 18: Incorrect. No stage matches; perhaps mixing G2 (24 chromatids pre-meiosis I) with reduction.
-
(D) 24: Incorrect. This is G2/mitotic metaphase total; meiosis I halves chromosomes but keeps chromatids paired.
Option Stage Context Chromatids Calculation Correct/Incorrect (A) 6 Haploid chromosomes only 6 chromosomes × 1 Incorrect (B) 12 Metaphase II per cell 6 chromosomes × 2 chromatids Correct (C) 18 Non-standard N/A Incorrect (D) 24 G2 or metaphase I total 12 chromosomes × 2 Incorrect Meiosis Stages Breakdown for Clarity
-
G1: 12 chromosomes, 12 chromatids.
-
After S: 12 chromosomes, 24 chromatids.
-
Metaphase I: 12 chromosomes (24 chromatids) align as 6 bivalents.
-
Post-meiosis I: 6 chromosomes, 12 chromatids per cell.
-
Metaphase II: 12 chromatids align per cell.
This aligns with genetic engineering and cell cycle studies in biotechnology.
-
