A DNA strand has 30% adenine. What percentage of the double-stranded molecule is guanine?
Answer and explanation
Correct answer: D. 20%
- Step 1: A pairs with T, so T is also 30%. Step 2. A + T = 60%, so G + C = 40%. Step 3. G = C, so G = 20%. Answer: 20%. Why not the others: 30% is the figure for thymine; 40% is guanine plus cytosine; 70% is the figure for non-adenine bases.
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