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GMAT Verbal Reasoning Practice Test 1

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Question : 30
Total: 100
Many seeds remain dormant (do not germinate) under conditions normally considered favorable to germination, namely, an adequate water supply, suitable temperature, and the normal composition of the atmosphere. Dormancy can have
various causes: the immaturity of the embryo within the seed, impermeability of the seed coat to water or gases, prevention of embryo development due to special requirements for temperature or light, or the presence of substances inhibiting
germination.
In many plant species a special type of dormancy exists in that seeds shed from the parent plant will not germinate until after a period of time known as after-ripening. The seeds of many plant species require storage in a dry environment to
after-ripen successfully. Not surprisingly, the amount of time in dry storage varies from species to species. Some barley varieties after-ripen within two weeks, whereas seeds of the marsh plant of the genus Cyperus after-ripen over a period of
seven years.
The necessity for after-ripening may be due to the need for further anatomical changes in the embryo or, sometimes, to a need for chemical changes in the seed. In this latter case, chemical changes in the seed may either lessen inhibitory
factors or produce substances that promote germination. Anatomical changes may be of different types: the apple embryo must undergo differentiation of its vascular tissue; in contrast, the embryo of an ash tree of the genus Fraxinus is
anatomically complete but must increase its size before germination can occur.
All of the following are referred to in the passage as possible causes of seed dormancy EXCEPT the... (Choose two.)
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