请教GWD1——25

niswzzhn

Recently biologists have been

       interested in a tide-associated

       periodic behavior displayed by

Line       the diatom Hantzschia virgata, a

  (5)       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

 (10)       burrowed in the sand during high

tide, and emerge on the sand sur-

face during the daytime low tide.

Just before the sand is inundated by

the rising tide, the diatoms burrow

 (15)      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

 (20)      in pressure caused by tidal move-

       ment.  However, when diatoms are

       observed under constant conditions

in a laboratory, they still display

periodic behavior, continuing to bur-

 (25)      row on schedule for several weeks.

This indicates that commuter diatoms,

rather than relying on environmental

cues to keep time, possess an inter-

nal pacemaker or biological clock

 (30)      that enables them to anticipate peri-

odic changes in the environment.

A commuter diatom has an unusu-

       ally accurate biological clock, a

consequence of the unrelenting

 (35)
                  environmental pressures to which

it is subjected; any diatoms that do

not burrow before the tide arrives

are washed away.提出现象及其研究

      This is not to suggest that the

 (40)     period of this biological clock is

immutably fixed.  Biologists have

concluded that even though a

diatom does not rely on the envi-

ronment to keep time, environmental

 (45)       factors—including changes in the

tide’s hydrostatic pressure, salin-

ity, mechanical agitation, and

temperature—can alter the period

of its biological clock according to

 (50)       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

 (55)      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

 (60)       exposed to the solar-day cycle as

well as to the tidal cycle, and some-

times display both solar-day and

tidal periods in a single behavior.

Commuter diatoms, for example,

 (65)       emerge only during those low tides

that occur during the day.环境因素对其生物钟的影响

GWD-1-Q25:

The passage suggests which of the following about the accuracy of the commuter diatom’s biological clock?

             

1. The accuracy of the commuter diatom’s biological clock varies according to changes in the tidal cycle.反

2. The unusual accuracy that characterizes the commuter diatom’s biological clock is rare among intertidal species.

3. The commuter diatom’s biological clock is likely to be more accurate than the biological clock of a species that is subject to less intense environmental pressures.定位32-36

4. The commuter diatom’s biological clock tends to be more accurate than the biological clocks of most other species because of the consistency of the tidal cycle.

5. The accuracy of the commuter diatom’s biological clock tends to fluctuate when the diatom is observed under variable laboratory conditions.

就算定位到32-36行我也没有找到比较的双方啊？怎么理解这道题目呢？谢谢大家。

carolinelmf

关键是“unrelenting

 (35)
                  environmental pressures to which

it is subjected”

面临残酷的环境条件

参考我的翻译：http://forum.chasedream.com/dispbbs.asp?boardID=25&ID=281893&page=1

niswzzhn

谢谢你啊，我已经下载了！

ledazhou

为什么A不对呢？