Question 67

DNA is structured as condensed chromosomes during prophase and metaphase of mitosis.

During both the prophase and metaphase stages of mitosis, DNA is organized into condensed chromosomes, which facilitates their separation and distribution to daughter cells.

A) Single chromatid

Single chromatids refer to the individual strands of DNA after replication. However, during prophase and metaphase, the DNA is not in the form of single chromatids; it is organized into pairs of sister chromatids that are still attached at the centromere.

B) Unreplicated chromosomes

Unreplicated chromosomes consist of a single DNA molecule without any sister chromatids. This form is not present during prophase and metaphase because, prior to these stages, DNA has already been replicated, leading to the formation of sister chromatids.

C) Separated chromatids

Separated chromatids occur during the anaphase stage of mitosis when sister chromatids are pulled apart to opposite poles of the cell. Therefore, this option does not accurately describe the structure of DNA during prophase and metaphase, where the chromatids remain together.

D) Condensed chromosomes

Condensed chromosomes are the correct description of DNA during prophase and metaphase. During these stages, the chromatin fibers condense into visible structures known as chromosomes, which are necessary for the proper segregation of genetic material.

Conclusion

The correct answer is D) condensed chromosomes, as this accurately reflects the structural organization of DNA during prophase and metaphase. All other options describe forms of DNA that either do not exist during these stages or occur at different phases of mitosis, thus confirming their inaccuracy.