2019年12月21日托福阅读真题+题目+答案：Life in an Estuary

2019年12月21日托福阅读真题+题目+答案：Life in an Estuary

An estuary is the wide part of a river where it flows into the sea. ⬛ It is affected by both marine influences(tides, waves, and the influx of saline water) and riverine influences (flows of fresh water and sediment) and is therefore not a perfectly stable environment. ⬛ As a result, an estuary contains fewer resident species than the nearby marine or freshwater ecosystems, resulting in less competition for food and space. ⬛ Because there is less competition, many estuarine species tend to be generalists that is,they are able to consume a variety of foods, depending on what is available. Species that can tolerate the salinity and temperature changes in estuaries can exploit the area's high productivity grow rapidly, and multiply into enormous populations. ⬛

1.The word “exploit”in the passage is closest in meaning to

O take advantage of

O add to

O restore

O Transform

2.According to paragraph 1, estuarine species tend to be generalists because

O they can eat both marine and freshwater species

O they need to grow rapidly and multiply while food is available

O fewer species compete for food in estuaries than in the sea or rivers

O larger variety of food is available in estuaries than in the sea

Many marine animals have body fluids that contain about the same concentration of salts as seawater and that are essentially isosmotic to the surrounding water; that is, the pressure of their body fluids is equal to the pressure of the seawater, and they neither gain nor lose water Because the marine environment remains relatively constant, they do not have a problem maintaining water balance. Animals that live in estuaries, however, must have some physiological mechanism for dealing with the varying salinity; otherwise, their tissues and cells would absorb water and lose salts as they encountered an environment with lower salinity than the sea. Thus, estuarine animals are either osmoconformers, which survive by having tissues and cells that tolerate the loss of salts through dilution, or osmoregulators, which maintain an optimal salt concentration in their tissues regardless of the salt content of their environment.

3.According to paragraph 2, all of the following are true about many animals living in seawater EXCEPT:

O Their body fluids contain the same proportion of salt and water as the sea.

O They lose water from their bodies into the sea and gain salt from the seawater.

O They are easily able to keep the water content of their body fluids in balance.

O Their body fluids have a pressure equal to the pressure of seawater.

4.According to paragraph 2, osmoconformers are able to live in estuaries by

O having tissues that keep the same salt level even when the salt content of the environment changes

O discarding excessive amounts of water in their bodies

O choosing estuarine locations where the salt content remains constant

O having tissues that are able to function even when their salt level decreases

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