Question

A somatic cell that has just completed the S phase of its cell cycle, as compared to gamete of the same species has
A. Twice the number of chromosomes and four times the amount of DNA.
B. Four times the number of chromosomes and twice the amount of DNA.
C. Twice the number of chromosomes and twice the amount of DNA.
D. Same number of chromosomes but twice the amount of DNA.

Answer 1

The cell cycle is an important event that leads to the formation of daughter cells. It contributes to gamete formation for sustaining generations, as well as in tissue repair.

Complete Answer:
The S-phase or Synthetic phase of the cell cycle is the phase in which DNA replication takes place. It occurs in between the two growth phases, G1 and G2 phases. Since the cell mentioned in the question is somatic or vegetative in nature, it is diploid in nature. Therefore after the S phase, the cell possesses twice the amount of chromosome number, and a corresponding four times the amount of DNA as compared to the haploid gamete of the same species.
Considering the other given options:
B. In this option, the amount of DNA cannot be less than the number of chromosomes. Since one chromosome is made of two DNA molecules. Thus this option is incorrect.
C. The option is incorrect since the number of chromosomes and the amount of DNA cannot be the same. Also, the gametes produced would be haploid, and the somatic cells after the S phase would contain twice the genetic material as compared to normal vegetative cells.
D. The chromosome number cannot be kept constant after the S phase.

Thus from the above-given options, the most appropriate option is A, that is, the cell should consist of twice the number of chromosomes and four times the amount of DNA.

Note: The cell cycle in eukaryotic organisms consists of two major stages, the interphase constituting a majority of the cycle and the mitotic or the cell division phase. During the interphase, the cell grows in size. During the mitotic phase, cell division or cytokinesis takes place.