Question

If spores have 10 chromosomes and 20 picogram DNA then what would be the chromosome number and DNA amount in spore mother cell at the end of S-phase in the life cycle of the same plant?

• A. 40 chromosomes and 80 pg DNA
• B. 20 chromosomes and 80 pg DNA
• C. 20 chromosomes and 40 pg DNA
• D. 40 chromosomes and 40 pg DNA

Answer 1

The correct option is B 20 chromosomes and 80 pg DNA

spore cell

n= 10

c= 20

mother cell

2n=2×10=20

2c=2×20=40

after S -phase chromosome no. remains same but DNA content doubles

2n=20

4c=4×20=80

Hence, correct option is (B)