Question

Paramecium is a single-cell eukaryotic organism that can reproduce by mitotic ell division. Prior to the M phase of the cell cycle, which of the following must occur?

A. The nuclear envelope must disintegrate.
B. The nucleus must divide.
C. The cell must replicate its chromosomes.
D. The cell must first be fertilized.
E. Chromatids must be separated.

Answer 1

Before the M phase of the cell cycle in Paramecium, the cell must replicate its chromosomes to ensure each daughter cell receives a complete set of genetic information for subsequent cell division.

Step-by-step explanation:

Prior to the M phase of the cell cycle in Paramecium, the cell must replicate its chromosomes. This process occurs during the interphase, preceding the onset of mitosis. The replication of chromosomes ensures that each daughter cell will receive a complete set of genetic information following cell division.

While Paramecium do possess two nuclei, the macronucleus and the micronucleus, the replication of chromosomes relevant here pertains to the preparation for mitotic cell division, which is an asexual reproduction mechanism, not the sexual reproduction process that involves the micronucleus.

Detailed processes such as the breakdown of the nuclear envelope, the division of the nucleus, and the separation of chromatids occur as subsequent steps during the mitotic phases, particularly during prophase, anaphase and ensuing phases. It is also noteworthy that the cell does not need to be fertilized for mitosis, as this is a method of asexual reproduction.