Question

DNA replication occurs during
A. Prophase
B. Metaphase
C. Cytokinesis
D. Interphase
E. Telophase

Answer 1

Hint: Cell cycle is the cycle of the multiplication of the cells. DNA replication occurs during the preparatory phase of the cell cycle. It occurs during the synthetic phase. Moreover, the S phase is a part of the Interphase of the cell cycle.

Complete answer: Interphase is that phase of the cell cycle where the cell is in preparatory mode. DNA replication occurs during the synthetic phase of the Interphase. During the S phase, the DNA replicates, and the histone protein synthesis occurs. The centrioles also get duplicated.
a) During prophase, nuclear membrane and nucleolus disappear. The chromosomes condense gradually and become short and thick. The arms of the chromosome break into chromatids. Centrioles pairs move towards opposite poles and the formation of astral rays begins.
b) Metaphase – In metaphase, chromosomes condense further and attain maximum condensation. All the chromosomes are arranged on the equatorial plate. Astral rays grow and attach with the chromomere.
c) Cytokinesis – Cytokinesis occurs during the M phase of the cell cycle. Cytokinesis is the division of the cytoplasm. In plants, cytokinesis occurs with the help of the cell plate method. In animal cells, it occurs with the help of the cell furrow method.
d) Telophase – Telophase occurs during the M phase. Karyokinesis is the division of the nucleus. It is the fourth or the last phase of karyokinesis. Chromatids from both sides finally reach the opposite poles. The decondensation of chromosomes continues. Nuclear membrane and nucleolus reappear gradually and finally, two nuclei are formed in a cell.
Hence, the correct answer is option D.

Note: Interphase is the most metabolically active phase because the cell prepares itself for the cell division. It is also known as the preparatory phase. Interphase is further divided into three phases – \({G_1}\) phase, S phase, and \({G_2}\) phase. It is the longest phase of the cell cycle.