PREP 2007 CR1 第48题

elephantsmall

Parasitic wasps laytheir eggs directly into the eggs of various host insects in exactly the rightnumbers for any suitable size of host egg. If they laid too many eggs in a host egg, the developing wasp larvaewould compete with each other to the death for nutrients and space.  If too few eggs were laid, portions of thehost egg would decay, killing the wasp larvae.

Which of the followingconclusions can properly be drawn from the information above?

(A) The size of thesmallest host egg that a wasp could theoretically parasitize can be determinedfrom the wasp's egg-laying behavior.

(B) Host insects lackany effective defenses against the form of predation practiced by parasiticwasps.

(C) Parasitic waspslearn from experience how many eggs to lay into the eggs of different hostspecies.

(D) Failure to layenough eggs would lead to the death of the developing wasp larvae more quicklythan would laying too many eggs.

(E) Parasitic waspsuse visual clues to calculate the size of a host egg.

答案A

为什么？smallest host egg是什么？

Gabby308

Again, this is a must be true question, meaning the correct answer

MUST be found in the passage. No where in the passage mentioned the

"experience" from which the wasp learned the trick. Thus, C) is wrong.

For example, it is possible this trait is genetically based.

huosijie

C的问题在哪里？

Gabby308

To put it simply, if a nest has 20 eggs, and the wasp laid 9 eggs into one egg and more than 9 in the other 19, then the egg received 9 wasp eggs is the smallest egg.

elephantsmall

只能说number和size存在一种函数关系（对每一个size，number不能多也不能少，一一对应）。但这种函数关系是怎样的就不一定了吧，如果size是x，number是y，x不一定有最小值哦，举例：反函数（或类似的函数曲线）

Gabby308

This is a must be true type of question.

A is the correct answer. The stimulus says "Parasitic wasps lay their eggs directly into the eggs of various host insects in exactly the right numbers for any suitable size of host egg." If so, the wasp can adjust the number of eggs laid according to the size of the host egg.  So you simply sit next to the host eggs and count how many eggs the parasitic wasp lays. Make a chart and compare. The host egg receiving the lowest amount of parasit eggs would be the smallest host egg.