Written by Prerak Juthani (PEACE Advisor) 

Which of the following statements is incorrect?

a)    human cells in G2 have 92 strands of DNA

b)   human cells in G2 have 46 strands of DNA

c)    human cells in G2 have 46 chromosomes

d)   both b and c

e)    both a and c 

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The correct answer is B. 

The important part is that DNA is duplicated in the S phase, which means that one piece of DNA will become 2 pieces of DNA. In this case, since G2 comes AFTER the S phase, the DNA molecules will all be duplicated. Since humans have 46 chromosomes, that means they have 46 strands of DNA BEFORE they are duplicated. However, in G2, the chromosomes ARE DUPLICATED, and thus, you have 92 strands of DNA – but you still have the 46 chromosomes (you will ALWAYS have 46 chromosomes because if that number changed, we all would be severely mutated each type cells divided). Thus, at the G2 phase, human cells DO have 92 strands of DNA (the 46 chromosomes are duplicated), but the number of chromosomes still is 46. Thus, A and C are correct, which is why B is the statement that is incorrect. 

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