Question

Which of the following statements about RNA is TRUE?

a) The percent of A always equals the percent of T.
b) The percent of A always equals the percent of U.
c) The percent of A + U always equals the percent of C + G.
d) Two of the above
e) None of the above.

Answer 1

The true statement about RNA is that the percent of adenine (A) always equals the percent of uracil (U) and the combined percent of A + U equals the percent of cytosine (C) + guanine (G).

Step-by-step explanation:

Among the offered statements about RNA, the true statement is b) The percent of A always equals the percent of U. In RNA, adenine (A) pairs with uracil (U), taking the place of thymine (T) which is found in DNA. Therefore, they are present in equal amounts in RNA. Statement c) The percent of A + U always equals the percent of C + G is also true for RNA, just as in DNA, where the amount of adenine and thymine equals the amount of guanine and cytosine. This is known as the Chargaff's rule and it applies to RNA with uracil in place of thymine. However, the RNA molecule is single-stranded and does not form a double helix as DNA does. The mention of 'T' in relation to RNA is incorrect because RNA contains uracil instead of thymine, thus making statements involving 'T' inapplicable to RNA.