Recently biologists have been interested in a tide-associated periodic behavior displayed by the diatom Hantzschia virgata, a microscopic golden-brown alga that inhabits that portion of a shoreline washed by tides (the intertidal zone). Diatoms of this species, sometimes called “commuter” diatoms, remain burrowed in the sand during high tide, and emerge on the sand surface during the daytime low tide. Just before the sand is inundated by the rising tide, the diatoms burrow again. Some scientists hypothesize that commuter diatoms know that it is low tide because they sense an environmental change, such as an alteration in temperature or a change in pressure caused by tidal movement. However, when diatoms are observed under constant conditions in a laboratory, they still display periodic behavior, continuing to burrow on schedule for several weeks. This indicates that commuter diatoms, rather than relying on environmental cues to keep time, possess an internal pacemaker or biological clock that enables them to anticipate periodic changes in the environment. A commuter diatom has an unusually accurate biological clock, a consequence of the unrelenting environmental pressures to which it is subjected; any diatoms that do not burrow before the tide arrives are washed away.
This is not to suggest that the period of this biological clock is immutably fixed. Biologists have concluded that even though a diatom does not rely on the environment to keep time, environmental factors—including changes in the tide’s hydrostatic pressure, salinity, mechanical agitation, and temperature—can alter the period of its biological clock according to changes in the tidal cycle. In short, the relation between an organism’s biological clock and its environment is similar to that between a wristwatch and its owner: the owner cannot make the watch run faster or slower, but can reset the hands. However, this relation is complicated in intertidal dwellers such as commuter diatoms by the fact that these organisms are exposed to the solar-day cycle as well as to the tidal cycle, and sometimes display both solar-day and tidal periods in a single behavior. Commuter diatoms, for example, emerge only during those low tides that occur during the day.
The passage suggests which of the following about the accuracy of the commuter diatom’s biological clock?
C选项对应原文这一句：A commuter diatom has an unusually accurate biological clock, a consequence of the unrelenting environmental pressures to which it is subjected.说diatom有这非同寻常准确的生物钟，这是因为它承受在的残忍而不间断的环境压力的结果。所以这巨大的环境压力解释了diatom的不寻常的准确性
C难道不是说反了么？原文说持续的环境压力导致不同寻常的准确度；C说less intensive pressure 导致high accurate
你看错了。。。选项说的是more accurate than
0 0 回复 2019-10-10 19:17:03
A commuter diatom has an unusually accurate biological clock, a consequence of the unrelenting environmental pressures to which it is subjected;
错选了A，不过确实说accuracy受潮汐影响，我觉得不是很恰当（实验室里都没潮汐了不是照样精准么），C其实还是在里面有提到他们这种精确的生物钟是由于压力大的环境导致的 （要是不在high tide来的时候burrow就会被冲走）恶劣的环境练就了他们这么精准的生物钟，这样看C确实挺有道理的
讲道理，没做这道题前，怎么也想不到be subjected to 是遭受经受的意思。 I am subjected to the torture of Gmat.
0 0 回复 2018-05-20 23:10:04
. A commuter diatom has an unusually accurate biological clock, a consequence of the unrelenting environmental pressures to which it is subjected
unrelenting unrelenting ---词义的准确度！！
A选项对应原文第二段双破折号的后面部分 但是原文只是说alter the period of 并没有说 the accuracy will vary。也就是说周期虽然会变化 但是准确性不一定变化。就像一年12个月每个月的天数不同（period varies） 但是每个月的时间都是精确的（the accuracy does not change）一样