Meiosis II is similar to mitosis in which of the following key aspects of chromosome behaviour?

Introduction / Context:
Cell division can occur by mitosis or meiosis. Meiosis involves two successive divisions, meiosis I and meiosis II, and is essential for forming gametes. Many exam questions ask you to compare meiosis II with mitosis, because in several ways meiosis II resembles a mitotic division. This question asks which specific aspect of chromosome behaviour makes meiosis II similar to mitosis.

Given Data / Assumptions:

• The focus is on meiosis II, not meiosis I.

• Options mention ploidy of daughter cells, sister chromatid separation, DNA replication, and crossing over.

• You should know the sequence of events in meiosis and mitosis.

• Only one option correctly describes a similarity between meiosis II and mitosis.

Concept / Approach:
In mitosis, a diploid cell replicates its DNA once and then divides to form two diploid daughter cells. During mitotic anaphase, sister chromatids separate and move to opposite poles. Meiosis consists of two divisions. In meiosis I, homologous chromosomes pair, undergo crossing over, and then separate, producing haploid cells with duplicated chromosomes. In meiosis II, these haploid cells divide again without another round of DNA replication. The key event in meiosis II is separation of sister chromatids, very similar to what happens in mitosis, but starting from a haploid set. Therefore, sister chromatid separation is the main similarity between meiosis II and mitosis.

Step-by-Step Solution:
Step 1: Recall that in meiosis I, homologous chromosomes pair, undergo crossing over, and then are pulled apart during anaphase I. Step 2: After meiosis I, each daughter cell is haploid but still has duplicated chromosomes consisting of two sister chromatids. Step 3: During meiosis II, these sister chromatids line up at the metaphase plate and are separated during anaphase II. Step 4: This pattern of sister chromatid separation is what occurs in mitosis, where each chromosome splits into two chromatids that move to opposite poles. Step 5: Examine option A, which claims that daughter cells are diploid. In meiosis II, daughter cells remain haploid, so this is not a similarity. Step 6: Option C states that DNA replicates before meiosis II, but in reality DNA replication occurs only once before meiosis I, not between the two meiotic divisions. Step 7: Option E describes pairing and crossing over of homologous chromosomes, which happens during prophase I of meiosis, not in meiosis II or mitosis. Step 8: Hence, the correct similarity is sister chromatid separation during anaphase, as stated in option B.

Verification / Alternative check:
Cytology diagrams show that in meiosis II, the arrangement of chromosomes on the spindle and the splitting of centromeres resemble mitotic metaphase and anaphase. Texts explicitly note that meiosis II is similar to a normal mitotic division except that it begins with haploid cells. They also emphasise that DNA replication does not occur again between meiosis I and II. These descriptions confirm that the critical shared feature is the separation of sister chromatids, not ploidy or crossing over.

Why Other Options Are Wrong:

Daughter cells are diploid: In meiosis II, the final cells are haploid, so this does not match mitotic outcome for diploid organisms.

DNA replicates before the division: Replication occurs only once before meiosis I, not before meiosis II.

All of the above: Incorrect because multiple individual statements are wrong.

Homologous chromosomes pair and cross over: This is characteristic of meiosis I, not mitosis or meiosis II.

Common Pitfalls:
Students often confuse meiosis I and meiosis II or think that DNA replication happens before each division. Another pitfall is to assume that meiosis II returns the cell to a diploid state, which is not correct. To avoid mistakes, remember the simple rule that meiosis I is reductional, separating homologous chromosomes, and meiosis II is equational, separating sister chromatids like mitosis but starting with haploid cells.

Final Answer:
Meiosis II is similar to mitosis in that sister chromatids separate and move to opposite poles during anaphase.