SAT Subject Biology Practice Question 391: Answer and Explanation

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Question: 391

1. If one ribose molecule were bonded to one adenine molecule and one phosphate molecule, we would have a

A. ribosome
B. nucleotide
C. nucleic acid

Correct Answer: B


B You should immediately recognize ribose as being the sugar used in RNA nucleotides, thereby eliminating choice A. Because the question asks about a single ribose molecule, you can eliminate choice C as well. Nucleic acids are made up of many nucleotides, containing many ribose molecules. Choices D and E are very tempting because they have adenine in them, and the question asks about ribose bonded to adenine. However, ATP stands for adenosine triphosphate-which means it has three phosphates-and ADP stands for adenosine diphosphate-which means it has two phosphates. The question specifies that only a single phosphate is included. The best answer is choice B-a nucleotide.

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