Chapter 10, Problem 6A

Summary Introduction

Introduction:

In animals the sexual life cycle involves meiosis. Meiosis involves two consecutive cell divisions called meiosis I and meiosis II. The two divisions produce a set of four haploid daughter cells that are not identical. Meiosis is important because it results in genetic variation.

Answer to Problem 6A

Correct answer :

The correct answer is option D. they will divide into sister chromatids.

Explanation of Solution

Explanation/justification for the correct answer:

OptionD. they will divide into sister chromatids −During metaphase II, as can be seen in the given diagram, the haploid chromosomes are lined up at the equator of the cell. The spindle fibers attach to the centromere of each chromosome. The next stage is anaphase II during which the sister chromatids are pulled apart at the centromere by the spindle fibers. The sister chromatids then move towards the opposite poles of the cell. Hence, this is the correct option.

Explanation for incorrect answer:

Option A. they will experience replication- After metaphase II, the sister chromatids separate and move to opposite poles. They do not undergo replication.Hence, this is not the correct option.

Option B. they will experience fertilization- After metaphase II, the sister chromatids separate and move to opposite poles. They do not undergo fertilization.Hence, this is not the correct option.

Option C. their number per cell will be halved- As can be seen in the given diagram, the pairs of homologous chromosomes are not lined up at the equator of the cell. Only haploid chromosomes are lined up at the equator. The number of chromosomes is already halved after meiosis I. After metaphase II, the sister chromatids separate and move to opposite poles. Hence, this is not the correct option.