If the total amount of adenine and thymine in a double-stranded DNA is 45%, the amount of guanine in this DNA will be
(2) In a DNA segment amount of adenine is equal to thymine. According to given information adenine and thymine constitutes 45% of DNA. So, guanine and cytosine will constitute 55%. Amount of guanine is equal to cytosine so amount of guanine in DNA will be 55/2 = 27.5%.