SAT Subject Biology Practice Question 420: Answer and Explanation

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Question: 420

10. 2-butoxyethanol, a substance found in a general household cleaner, was tested for toxicity to termites. Solutions were made that contained various parts per million (PPM) of 2-butoxyethanol, and 15 mL of each of these diluted solutions was mixed with 150 g of wood chips. Twenty mature termites were added to the wood chips, and the number surviving after 24 hours was determined and recorded. The following graph presents the results.

Based on the data for 20 PPM 2-butoxyethanol, what concentration of solution would be required to kill the entire 20-member termite population?

A. 40 PPM
B. 50 PPM
C. 60 PPM
D. 70 PPM
E. 80 PPM

Correct Answer: B


B A dose of 20 PPM kills 40% of the population. 40% × 2.5 = 100%, so 20 PPM × 2.5 = 50 PPM.

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