Cell Cycle and Cell Division Question 6
6. A somatic cell that has just completed the $S$ phase of its cell cycle, as compared to gamete of the same species, has :
[2015 RS]
(a) same number of chromosomes but twice the amount of DNA
(b) twice the number of chromosomes and four times the amount of DNA
(c) four times the number of chromosomes and twice the amount of DNA
(d) twice the number of chromosomes and twice the amount of DNA
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Answer : b
Hints & Solutions
(b) When S-phase completes, a somatic cell contains $2 n$ number of chromosomes and $4 C$ content of DNA. During DNA replication, the unwinding of strands leaves a single strand vulnerable. During $S$ phase, any problems with DNA replication trigger a “checkpoint” - a cascade of signaling events that puts the phase on hold until the problem is resolved.
