Our terrestrial food supply comes from ecosystems transformed to produce a few comestible species through the removal of competitors, predators, and pests, but marine capture fisheries depend on the overall productivity of natural ecosystems. There is, however, increasing concern about the impact of fishing and other human activities on marine ecosystems, which are now far from pristine. One option for moving toward both biodiversity and terrestrial food supply goals is to produce greater yields from less land, thereby freeing land for conservation purposes. By contrast, the objective of maintaining or restoring the biodiversity of marine ecosystems may conflict with the objective of maintaining or increasing our food supply from the sea, since the level of fishing required to achieve the latter may compromise the former.
1. The primary purpose of the passage is to
A：Examine the impact of certain research findings regarding changes to ecosystem biodiversity.
B：Discuss a possible implication of a difference between terrestrial and marine food supply sources.
C：Describe the consequences of a certain kind of interaction between terrestrial and marine ecosystems.
D：Identify an area of ecosystem research in which there are significant uncertainties.
E：Present evidence that undermines one side of a debate about biodiversity and supports the other.
答案：B
2. According to the passage, increasing the food yield per unit of land can have which of the following effects?
A：Enabling more land to be used for development purposes
B：Compromising progress toward conservation goals
C：Helping protect comestible species from competition and predation
D：Helping reduce pressure on marine ecosystems
E：Helping restore the biodiversity of terrestrial ecosystems
答案：E
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