扫描二维码，直接登录
题库 / Prep2007E1-CR-3
The prairie vole, a small North American grassland rodent, breeds year-round, and a group of voles living together consists primarily of an extended family, often including two or more litters. Voles commonly live in large groups from late autumn through winter; from spring through early autumn, however, most voles live in far smaller groups. The seasonal variation in group size can probably be explained by a seasonal variation in mortality among young voles.
Which of the following, if true, provides the strongest support for the explanation offered?
It is in the spring and early summer that prairie vole communities generally contain the highest proportion of young voles.
Prairie vole populations vary dramatically in size from year to year.
The prairie vole subsists primarily on broad-leaved plants that are abundant only in spring.
Winters in the prairie voles' habitat are often harsh, with temperatures that drop well below freezing.
Snakes, a major predator of young prairie voles, are active only from spring through early autumn.
草原田鼠，一种北美小型草原啮齿动物，每年繁殖一次，一群田鼠生活在一起主要有大家庭组成，经常包括2个以上的幼崽。田鼠在晚秋到冬季一般生活在大家庭；春到早秋，大部分生活在更小的家庭。家族大小随季节变化可能被幼年田鼠的死亡率随季节变化来解释
增强题 结论落脚在在幼年田鼠的死亡率与季节变化的关系，要与之相关才可能增强
A 春和早夏田鼠社群一般有更大比例幼鼠；没谈死亡率，排
E 蛇，幼鼠的主要捕食者，只在春天和早秋活动；说明在春和早秋幼鼠的死亡率高，对应的家庭小，搭桥增强，正确。
登录 或 注册 后可以参加讨论