SAT Subject Biology Practice Question 425: Answer and Explanation

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Question: 425

15. Unfertilized frog oocytes were bathed in a neutral, isotonic solution (Frog Ringer's solution) to prevent changes in volume due to osmosis. The Frog Ringer's solution was supplemented with radiolabeled amino acids. A sample of oocytes was taken every 30 minutes and assayed for radioactivity.

At Time 1, the oocytes were fertilized. Samples were taken at five-minute intervals after fertilization and assayed for radioactivity. The results are presented in the graph below.

The radioactivity measured after fertilization was taken up by

A. being incorporated into DNA
B. being incorporated into proteins
C. attaching to the cell membrane
D. endocytosis
E. associating with carbohydrates

Correct Answer: B

Explanation:

B Radiolabeled amino acids would be incorporated into proteins.

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