[Campbell Biology P.134] Which of the following statements about the components of nucleic a... | Practice Question

Which of the following statements about the components of nucleic acids are correct? Select all that apply

  • A: A nucleoside consists of a nitrogenous base, a sugar, and a phosphate group.
  • B: Purines are larger than pyrimidines and consist of a six-membered ring fused to a five-membered ring.
  • C: Cytosine, Thymine, and Uracil are examples of pyrimidines.
  • D: In DNA, the nitrogenous base uracil replaces thymine.

Explanation

The text states that 'Purines are larger, with a six-membered ring fused to a five-membered ring,' confirming B. Figure 5.23c clearly labels Cytosine, Thymine, and Uracil under 'Pyrimidines,' confirming C. Option A describes a nucleotide, not a nucleoside. Option D is incorrect as Thymine is specific to DNA and Uracil to RNA.