Question

Find out the numnber of chromosomes and the amount of DNA in a spore mother cell of bryophytes in $G_2$ stage , if the spore contains $5$ chromosomes and $5$ picograms of DNA

• A. $5$ chromosomes ,$5$pg DNA
• B. $10$ chromosome ,$20$ pg DNA
• C. $10$ chromosome ,$10$ pg DNA
• D. $20$ chromosome $20$ pg DNA

Answer 1

Answer: (B)

$10$ chromosome ,$20$ pg DNA

It is given that the spore of bryophytes contains 5 chromosomes and 5 picograms of DNA. Spore is haploid in nature. Spore mother cell is diploid in nature. Due to this, the spore mother cells will have double amount of chromosome and DNA. During G${}_2$ phase, the amount of DNA remains the same and DNA doubles. In a spore mother cell of bryophytes, the chromosome number will be 10 (2n). However, amount of DNA will be double, that is 20 (2n) picograms.

Thus, the correct answer is '10 chromosome, 20 pg DNA.'