SAT Subject Biology Practice Question 308: Answer and Explanation
18. Tropisms refer to movements made by plants toward or away from certain stimuli. "Positive" tropisms refer specifically to movements toward a stimulus, whereas "negative" tropisms refer to movements made away from a stimulus.
The stem and leaves of the plant grow up, away from the soil. This is an example of
A. negative geotropism
B. positive geotropism
C. negative phototropism
D. positive hydrotropism
E. negative hydrotropism
Correct Answer: A
A The prefix geo refers to the earth, or soil; thus we can eliminate choices C, D, and E. Because the plant is growing away from the earth, this is a negative tropism and we can eliminate choice B.