SAT Subject Biology Practice Question 389: Answer and Explanation

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Question: 389

19. All of the following are needed for photosynthesis EXCEPT

A. light
B. glucose
C. chlorophyll
D. water
E. carbon dioxide

Correct Answer: B


B First of all, remember that this is a LEAST/EXCEPT/NOT question. Circle the word "EXCEPT" and draw a vertical line through the answer choices to remind yourself that you are looking for the "wrong" answer, in this case, the word that doesn't fit with the description in the question. Basically, the process of photosynthesis involves using a green pigment called chlorophyll (choice C) to capture light energy (choice A). Water (choice D) is used to convert the light energy into chemical energy (ATP and NADPH). This chemical energy is used to convert carbon dioxide (choice E) into carbohydrates. Glucose (choice B) is an end product of photosynthesis. It isn't needed in the course of the reactions.

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