Chapter 10, Problem 4A

Summary Introduction

Introduction :

Meiosis is a method of cell division in which occurs in reproductive cells. One meiosis results into four daughter cells with half of the chromosome compared to the mother cell. This division is completed in two divisions, Meiosis I and Meiosis II. Meiosis I is further divided into five namely prophase I, metaphase I, anaphase I and telophase I. Meiosis I is a reductional division which results into two daughter cells with half of the chromosome.

Answer to Problem 4A

Correct answer :

The correct answer is option (B) 12.

Explanation of Solution

Explanation/justification for the correct answer :

Option (B) 12. During metaphase I of meiosis, the homologous chromosomes line up as pairs at the equator of the cell and the spindle fibres attach to the centromere of each homologous chromosome. So, if a cell has 12 chromosomes or 6 pairs of homologous chromosomes, the number of chromosomes remains the same during meiosis I. Thus, the correct answer is an option (B).

The explanation for the incorrect answer :

Option (A) 6. If a cell has 12 chromosomes or 6 pairs of homologous chromosomes, the number of chromosomes will be 6 at the end of meiosis I. Thus, this is an incorrect option.

Option (C) 24. If a cell has 12 chromosomes or 6 pairs of homologous chromosomes, the number of chromosomes cannot be 24 at metaphase I. Thus, this is an incorrect answer.

Option (D) 36. 36 chromosomes at metaphase I of meiosis is not possible if a cell has 12 chromosomes. Thus, this is an incorrect answer.