第三篇 Homeostasis,an animal's maintenance of certain internal variables within an acceptable range,particularly in extreme physical environments,has long interested biologists.The desert rat and the camel in the most water-deprived environments,and marine vertebrates in an all-water environment,encounter the same regulatory problem:maintaining adequate Internal fluid balance. For desert rats and camels,the problem is conservation of water in an environment where standing water is nonexistent,temperature is high, and humidity is low.Despite these handicaps, desert rats are able to maintain the osmotic pressure of their blood,as well as their total body water content,at approximately the same levels as other rats.one countermeasure is behavioral:these rats stay in burrows during ‘the hot part of the day, thus avoiding loss of fluid through panting or sweating,which are regulatory mechanisms for maintaining internal body temperature by evaporative cooling. Also,desert rats’ kidneys can excrete a urine having twice as high a salt content as sea water. Camels,on the other hand,rely more on simple endurance.They cannot store water, and their reliance on an entirely unexceptional kidney results in a rate of water loss through renal function significantly higher than that of desert rats.As a result,camels must tolerate losses in body water of up to thirty percent of their body weight.Nevertheless,camels do rely on a special mechanism to keep water loss within a tolerable range:by sweating and panting only when their body temperature exceeds that which would kill a human,they conserve internal water. Marine vertebrates experience difficulty with their water balance because though there is no shortage of seawater to drink, they must drink a lot of it to maintain their internal fluid balance.But the excess salts from the seawater must be discharged somehow,and the kidneys of most marine vertebrates are unable to excrete a urine in which the salts are more concentrated than in seawater.Most of these animals have special salt-secreting organs outside the kidney that enable them to eliminate excess salt.
Questions 12-15 refer to the passage above. 12. Which of the following most accurately states the purpose of the passage? (A) To compare two different approaches to the study of homeostasis (B) To summarize the findings of several studies regarding organisms maintenance of internal variables in extreme environments (C) To argue for a particular hypothesis regarding various organisms conservation of water in desert environments (D) To cite examples of how homeostasis is achieved by various organisms (E) To defend a new theory regarding the maintenance of adequate fluid balance 13. According to the passage,the camel maintains internal fluid balance in which of the following ways?
I. By behavioral avoidance of exposure to conditions that lead to fluid loss II. By an ability to tolerate high body temperatures III. By reliance on stored internal fluid supplies (A) I only (B) II only (C) I and II only (D) II and III only (E) I,II , and Ill 14.It can be inferred from the passage that some mechanisms that regulate internal body temperature t like sweating and panting, can lead to which of the following?
(A) A rise in the external body temperature (B) A drop in the body's internal fluid level (C) A decrease i n the osmotic pressure of the blood (D) A decrease in the amount of renal water loss (E) A decrease in the urine's salt content 15.It can be inferred from the passage that the author characterizes the camel's kidney as"entirely unexceptional"(1ine 27)primarily to emphasize that it
(A) functions much as the kidney of a rat functions (B) does not aid the camel in coping with the exceptional water loss resulting from the extreme conditions of its environment (C) does not enable the camel to excrete as much salt as do the kidneys of marine vertebrates (D) is similar in structure to the kidneys of most mammals living in water-deprived environments (E) requires the help of other organs in eliminating excess salt
第三篇的问题共4个问题
1)第一段第8行encounter the same regulatory problem和第二段20行which are regulatory mechanisms这里的regulatory是什么意思呢,我试着译一下(1)encounter the same regulatory problem面临相同的调整问题,是这个意思吗? (2)which are regulatory mechanisms这些都是调整机制,是这个意思吗? 通过看文章的全文内容,我猜有调控内部水分平衡的意思在里面。是这样吗?
2)32行Nevertheless,adv.尽管如此,不过,然而, 我的问题:Nevertheless在这里的语气是表示转折吗?可我觉得按照这里上下文的意思看是进一步说明前面的30-32行这句话的As a result,camels must tolerate losses in body water of up to thirty percent of their body weight.因此,骆驼必须忍受身体的水分的损失直到身体重量30%,后面用Nevertheless,进一步说明 骆驼确实依靠一种特别的机制。。。。。。。camels do rely on a special mechanism to keep water loss within a tolerable range:
3)22行evaporative cooling,觉得这里有点有趣,evaporative是形容词,cool明明有名词词性,却用了动词词性现在分词的形式,有点不明白,能把这句用法分析一下吗?
4)14题A选项 (A) A rise in the external body temperature 我的问题:外部的身体温度指的是老鼠和骆驼的身体表面皮肤和毛皮的温度吗??? 说一下我当时做题的想法,我选这题的时候没选A但是我以为错在rise上,看了OG解释才知道是错在external上,文章讲的应该是内部温度,那内部温度指的是血管温度吗,内部温度与外部温度是怎么回事啊,还是外部温度是外部自然环境的温度呢??? 这道题这里还有一个问题:?如果A选项变成A drop in the internal body temperature的话对不对,主要还是没的搞懂这个喘气和发汗之后,体内的水份变少了,那么身体内部的温度是下降???还是保持不变呢???
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