Neet Solved Paper 2015 Question 56
Question: A somatic cell that has just completed the S-phase of its cell cycle, as compared to gamete of the same species has
Options:
A) twice the number of chromosomes and twice the amount of DNA
B) same number of chromosomes but twice the amount of DNA
C) twice the number of chromosomes and four times the amount of DNA
D) four times the number of chromosomes and twice the amount of DNA
Show Answer
Answer:
Correct Answer: C
Solution:
- In general, a gamete contains n number of chromosomes (haploid) and x amount of DNA. In comparison to the gamete, an (diploid) somatic cell usually have 2n number of chromosomes and 2x amount of DNA. But, after the cell enters and completes the S-phase of its cell cycle, the DNA content of the cell becomes double (due to its duplication). However, the number of chromosomes remains the same. Hence, the somatic cell that has undergone and completed its S phase of cell cycle will have twice the number of chromosomes and four times the DNA content. It can be explained as Chromosome no. DNA content Gamete $ n $ $ x $ Somatic cell (diploid) $ 2n $ $ 2x $ Somatic cell (after S-phase) $ 2n $ $ 4x $
