Question

If a dsDNA has 30% thymine, what is the percentage of cytosine present?

(a) 70%

(b) 30%

(c) 40%

(d) 20%

Answer 1

Answer is : (d) 20%

Thymine (T) pairs with Adenine (A) and Cytosine (C) pairs with Guanine (G). If thymine is 30%, adenine will also be equal, i.e. 30%. Now, as (T + A) = 60%, rest of 40% = (C + G), and as the quantity of C = G, C can be calculated as 40/2 = 20%.