In a DNA Double Helix

Question

In a DNA double helix,
A)the two DNA strands are identical.
B)purines pair with purines.
C)thymine pairs with cytosine.
D)the two DNA strands run antiparallel.

Accepted Answer

The statement "the two DNA strands run antiparallel" is correct. The two strands run in opposite directions, with one strand running in the 5' to 3' direction and the other strand running in the 3' to 5' direction. The other statements are incorrect: the two DNA strands are complementary but not identical, purines pair with pyrimidines, and thymine pairs with adenine (not cytosine).