Question

In the case of double-stranded DNA, which of the following base ratios are always equal to one?
a. $(A+T)/(G+C)$
b. $(A+G)/(C+T)$
c. $C/G$
d. $(G+T)/(A+C)$
Select the correct answer.

• A. $1$ and $2$
• B. $2$ only
• C. $2,3$ and $4$
• D. $1,3$ and $4$

Answer 1

The correct option is B $2$ only

B. 1 and 3

Solution : Chargaff's rules state that DNA from any species of any organism should have a 1:1 ratio of purine and pyrimidine bases (i.e., A+G = T+C) and, the amount of guanine should be equal to cytosine and the amount of adenine should be equal to thymine.

So the correct answer is "1 and 3".