Question

A cell has 18 chromosomes. How do the chromosomes change during metaphase? A. They separate into 18 identical chromatids. B. They separate into 36 identical chromatids. C. They align in a single row across the cell. D. They align in two rows across the cell, with 9 chromosomes per row.

Answer 1

During metaphase, chromosomes align in a single row across the center of the cell, on the metaphase plate. Option C is the correct answer, indicating that the 18 chromosomes line up as paired sister chromatids.

Step-by-step explanation:

During metaphase, a cell with 18 chromosomes undergoes a specific process in which the chromosomes align. The chromosomes cohere as pairs of sister chromatids due to the presence of cohesin proteins. These paired chromatids, still attached at the centromere, line up across the center of the cell, known as the metaphase plate or equatorial plane. Therefore, the correct answer to how the chromosomes change during metaphase is they align in a single row across the cell, which corresponds to option C. Each of the 18 chromosomes consists of two sister chromatids at this phase, remaining maximally condensed and jointly lined up, preparing for their subsequent separation during anaphase.