Thirty percent of the bases in a sample of DNA extracted from eukaryotic cells are adenine. What percentage of cytosine is present in this DNA?
A) 10 percent
B) 20 percent
C) 30 percent
D) 40 percent
E) 50 percent

Question

Quizplus · Accepted Answer

In DNA, adenine (A) pairs with thymine (T), and guanine (G) pairs with cytosine (C). If 30% of the bases are adenine, then 30% are thymine. This leaves 40% for guanine and cytosine combined. Since guanine and cytosine are present in equal amounts, cytosine makes up 20% of the bases.

Thirty Percent of the Bases in a Sample of DNA