Many microorganisms survive such environmental stresses as heat, cold

游客2024-01-11 33

问题          Many microorganisms survive such environmental stresses as heat, cold
   and desiccation not by rapid rates of mitosis, but by producing specialized cells
   designed to persist in a dormant state in hostile environments. Most fungi, for
Line example, yield single-celled spores, which, through wind distribution, can
(5)    survive for long periods of time before germinating and sprouting fungal
   filaments of their own. Other types of bacteria produce a special type of spore
   called an endospore, capable of withstanding such extremes as boiling and
   freezing temperatures, and even ultraviolet radiation.
         Though research results remain tentative, several factors may protect
(10) endospores from environmental stress: they have a low water content, unusual
   proteins and a tough spore coat absent in mature bacterial cells. When garden
   fruits and vegetables, which may contain botulism endospores, are preserved by
   canning at boiling temperatures, we know that these spores survive the heat
   and sprout in the food, and as a result, the bacteria generate the botulism toxin
(15) that can lead to food poisoning-proof of their magnificent resilience. [br] The author would regard the notion that certain proteins are essential to the survival of environmentally resistant endospores as

选项 A、unlikely
B、speculative
C、incontrovertible
D、irrelevant
E、unscientific

答案 C

解析

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Many microorganisms survive such environmental stresses as heat, cold

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