Question

When does DNA replication occur in the cell cycle? mitosis cytokinesis O meiosis both mitosis and meiosis sphase of interphase

Answer 1

1. The correct option is E.

DNA replication occurs in the S phase or the synthesis phase of the interphase of cell cycle. It is also the period where the cell synthesizes additional histone molecules that are required due to the doubling of the nuclear material.

Mitosis and meiosis cannot be the correct answer because these stages of the cell cycle are specific to chromosome segregation and formation of daughter cells. DNA replication occurs prior to these stages.

Cytokinesis is the process by which a cell divides into two daughter cells after the completion of mitosis (resulting in the formation of two daughter cells) or meiosis (resulting in the formation of four daughter cells). Therefore this cannot be the correct option.

2. The correct option is D.

Meiosis is a type of cell cycle that results in the reduction of chromosome number by half leading to the formation of haploid daughter cells. Germ cells undergo meiosis to produce haploid gametes (sperm and egg). So, a hermaphroditic worm will have both male and female reproductive organs and it will produce both sperm and egg cell by the process of meiosis.

Mitosis cannot be the correct option because it usually occurs in somatic cells that are not involved in the production of gametes.

Synapsis is not an independent cell cycle. It is a stage in the meiotic cell cycle where the homologous chromosomes join before crossing over.