[Campbell Biology P.135] According to the text and Figure 5.24a, which statement accurately ... | Practice Question

According to the text and Figure 5.24a, which statement accurately describes the structure of a DNA double helix?

  • A: The sugar-phosphate backbones are located on the outside of the helix, and the nitrogenous bases are paired in the interior.
  • B: The two polynucleotide strands run in parallel directions (both 5' to 3').
  • C: Hydrogen bonds primarily link the sugar-phosphate backbones together.
  • D: Adenine (A) pairs with cytosine (C), and guanine (G) pairs with thymine (T).

Explanation

The text and Figure 5.24a describe the DNA molecule as having 'sugar-phosphate backbones... on the outside of the helix' and 'nitrogenous bases are paired in the interior of the helix'. Hydrogen bonds hold these paired bases together.