Question

Select the incorrect statement regarding S phase of interphase
A. It occurs between G1 and G2
B. DNA replicates in the nucleus in this phase
C. Centrioles duplicate in the cytoplasm
D. As DNA is doubled, the number of chromosomes also doubles.

Answer 1

Hint: Cell cycle is basically a series of events in which the DNA replication, cell division takes place. Each cell has a different time period of the cell cycle. It is majorly divided into two phases.

Complete answer:
The two phases of cell cycle are Interphase and Mitosis phase. As the name suggests, In mitosis phase, the mitosis occurs and interphase is the phase or gap between two Mitosis phases.
Mitosis phase is short while interphase lasts long. Interphase is called the resting phase.
Interphase is divided into Gap1 phase, S phase, Gap2 phase.
1. G1 phase occurs between mitosis and start of DNA replication.
2.In the S phase, actual DNA replication and synthesis takes place.
3.In the G2 phase, synthesis of proteins occurs and cell growth continues.
Now analyze the options:

Option A: S phase occurs between G1and G2. This is correct regarding S phase. Therefore, this is the incorrect option.

Option B: DNA replication begins in the nucleus in S phase. This is correct regarding S phase. Therefore, this is the incorrect option.

Option C: Centrioles duplicate in the cytoplasm during S phase. This is correct regarding S phase. Therefore, this is the incorrect option.

Option D: In the S phase, DNA doubles but the number of chromosomes remains the same. This is not true regarding S phase. Therefore, this is the correct option.

Hence, the correct answer is option (D)

Note: Some cells do not divide further after G1 phase, exits and enter an inactive stage called quiescent stage. Plants show mitotic division in both haploid and diploid cells whereas animal cells only show in diploid cells.