If an organism's DNA contains 20% adenine nucleotides,what percentage of its DNA is composed of guanine nucleotides?
A) 10%
B) 15%
C) 20%
D) 30%
E) 40%

Question

Quizplus · Accepted Answer

DNA is composed of four nucleotide bases: adenine (A), thymine (T), guanine (G), and cytosine (C). These bases pair up in a specific way: A pairs with T, and G pairs with C. Because of this pairing, the percentage of adenine in DNA must equal the percentage of thymine, and the percentage of guanine must equal the percentage of cytosine.
If the DNA contains 20% adenine, then it must also contain 20% thymine. The remaining 60% must be composed of guanine and cytosine. Since these two bases pair up together, they must each make up half of the remaining 60%, or 30% each. Therefore, the percentage of guanine in the DNA is 30%.

If an Organism's DNA Contains 20% Adenine Nucleotides,what Percentage of Its