SAT Subject Biology Practice Question 347: Answer and Explanation

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Question: 347

17. Acid rain is formed after the burning of fossil fuels releases compounds containing nitrogen and sulfur into the atmosphere. Sunlight and rain bring about chemical reactions that convert these compounds into nitric acid and sulfur dioxide, which combine with water droplets to form acid rain. Acid rain typically has a pH of approximately 5.5.

The higher acidity of soil and water affects many living organisms adversely. As the pH of lake water falls, fish become ill and die. Table 1 shows the effects of pH on the size of adult fish.

Table 1

Mycorrhizal fungi, which form a mutualistic association with many plant roots, are particularly sensitive to the effects of acid rain. These fungi facilitate the absorption of water and nutrients by the plants; in turn, the plants provide sugars and amino acids without which the fungi could not survive.

What might be the best strategy to preven

A. Stock the lakes with bigger fish so that they can resist the effects of the acid better
B. Reduce the amount of fossil fuels that are burned
C. Supply plants with excess phosphorus and water
D. Supply fungi with excess sugars and amino acids
E. Add alkalines to soil and water to neutralize the acid

Correct Answer: B

Explanation:

B The best way to prevent damage from acid rain would be to prevent its formation by reducing the burning of the fossil fuels that cause it. There is no guarantee that bigger fish will resist the acidity any better than smaller fish (A is wrong), supplying plants with excess phosphorus will not help them take it up any easier (C is wrong), supplying fungi with sugars and amino acids will not help them overcome the effects of acid soil (D is wrong), and, even if alkalines will neutralize acid, they might be just as harmful to the environment (E is wrong)!

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