SAT Subject Biology Practice Question 346: Answer and Explanation
16. 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.
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.
If the pH of the soil were 7.0, what woul
A. The fungi would survive but the plant would be harmed.
B. The fungi would be harmed but the plant would survive.
C. The fungi would be slightly harmed and the plant would be slightly harmed.
D. Neither the fungi nor the plant would survive.
E. Neither the fungi nor the plant would be harmed.
Correct Answer: E
E pH 7.0 is neutral, thus neither the plant nor the fungi would be harmed.