SAT Subject Biology Practice Question 225: Answer and Explanation

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Question: 225

15. Scientists examined the effects of adding nutrients to waters off the Eastern coast of the United States. The graph shows the nutrient added and the resulting algae counts at six locations. No nutrients were added in the control condition.

Algae incorporate nitrogen and phosphorus compounds in the environment into which of the following macromolecules?

I. Carbohydrates

II. DNA

III. Protein

A. I and II
B. I and III
C. III only
D. II and III
E. I, II, and III

Correct Answer: D

Explanation:

Nitrogen and phosphorus are incorporated into nucleic acids, such as DNA, which feature a phosphate group in the backbone, and protein, which is composed of amino acids containing nitrogen atoms.

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