UMAT Practice Question 5

Botanists studied a rainforest in Nicaragua that had been ravaged by Hurricane Joan in 1988. They found that in the following ten years the number of tree species had increased by at least 200%, and up to 300%, in eight storm-affected plots. Other plots not affected by the hurricane showed little if any such increase.

From this information, it can be concluded that:

A. hurricanes play a very important role in ensuring the long-term survival of tropical rain forests.

B. when the dominant trees in an area of tropical rainforest are destroyed, other species are given a chance to flourish.

C. the overall life of tropical rainforest is increased if large areas are occasionally levelled to the ground.

D. the productivity of a tropical rainforest will be maximised if large areas are occasionally levelled to the ground.

Solution: In this question, you need to select the best of four imperfect options.

While the plots that were unaffected by the hurricane showed little if any increase, this doesn't mean that hurricanes are required for rainforest survival. They could still survive without increasing the number of species. Thus, option A is incorrect.

Option B seems to fit reasonably with the passage: the hurricane would result in the dominant trees being destroyed. Then, other species being allowed to flourish would result in the dramatic increase in the number of species seen in the areas affected by the hurricane. This option isn't perfect as it is more of an inference than a conclusion, but it is plausible.

Option C doesn't quite fit as well as B: while the variety of life is increased by the hurricane, the total amount of living things (overall life) might not have increased.

While the hurricane resulted in an increase in the number of species, this doesn't necessarily have any relationship to the productivity of the rainforest. Therefore, option D is incorrect.

As B was the best of the four options, it is correct.

The correct answer is B.