Which of the Following is True

Question

Which of the following is true?
A)The two strands of a DNA molecule are held together by covalent bonds.
B)A single strand within a DNA molecule is held together by hydrogen bonds.
C)The bases on one strand of DNA are held to the bases on the other strand by hydrogen bonds.
D)Hydrogen bonding between complementary base pairs causes the DNA molecule to twist into a spiral.

Accepted Answer

The complementary base pairs (A-T and C-G) are held together by hydrogen bonds between the bases on the two strands of DNA. The two strands themselves are held together by covalent bonds. Option D is partially correct, as hydrogen bonding does cause the DNA molecule to twist into a spiral, but it is not the only factor responsible for the overall structure of DNA. Option A is incorrect as covalent bonds do not hold the two strands of DNA together but rather bind nucleotides within each individual strand together. Option B is incorrect because a single strand within a DNA molecule does not contain complementary base pairs that can hydrogen bond with each other.