Question

The ratio constant for a species is

• A. A + G / C + T
• B. T+ C/G + A
• C. A + C / T + G
• D. G+ C / A+T

Answer 1

Answer: (D)

G+ C / A+T

According to Chargaff's base pair rule, DNA from any cell of an organism should have a 1:1 ratio of pyrimidine and purine bases, that is, the total amount of purines = total amount of pyrimidines. In this, the amount of guanine is equal to the amount of cytosine and the amount of adenine is equal to the amount of thymine. The ratio of A: T = 1 and the ratio of G: C = 1. According to Chargaff's rule, G + C / A + T ratio varies with the species but is constant for a species.

Thus, the correct answer is option D.