70. Which of the following best describes the author's attitude?
A. Forgiving B. Surprised C. Vindictive D. Concerned
VII/. Read the following passage and mark the letter A, B, C, or D on your answer sheet to
indicate the correct answer to each of the following questions
While most desert animals will drink water if confronted with it, for many of them the
opportunity never comes. Yet all living things have water, or they will expire. The herbivores
find it in desert plants. The carnivores slave their thirst with the flesh and blood of living prey.
One of the most remarkable adjustments, however, has been made by the tiny kangaroo rat, who
not only lives without drinking but subsists on a diet of dry seeds containing about 5% free water.
Like other animals, he has the ability to manufacture water in his body by a metabolic conversion
of carbohydrates. But he is notable for the parsimony with which he conserves his small
supply by every possible means, expending only minuscule amounts in his excreta and through
evaporation from his respiratory tract.
Investigation into how the kangaroo rat can live without drinking water has involved various
experiments with these small animals. Could kangaroo rats somehow store water in their bodies and
slowly utilize these resources in the long periods when no free water is available from dew or
rain? The simplest way to settle this question was to determine the total water content in the
animals to see if it decreases as they are kept for long periods on a dry diet. If they slowly use up
their water, the body should become increasingly dehydrated, and if they begin with a store of
water, this should be evident from an initial high water content. Result of such experiments with
kangaroo rats on dry diets for more than 7 weeks showed that the rats maintained their
bodyweight. There was no trend toward a decrease in water content during the long period of water
deprivation. When the kangaroo rats were given free access to water, they did not drink water.
They did nibble on small pieces of watermelon, but this did not change appreciably the water
content in their bodies, which remained at 66.3% to 67.2% during this period.
This is very close to the water content of dry-fed animals ( 66.5% ), and the
availability of free water, therefore, did not lead to any “storage” that could be meaningful as a
water reserve. This makes it reasonable to conclude that physiological storage of water is not a
factor in the kangaroo rat’s ability to live on dry food.
Bạn đang xem 70. - TẢI BỘ ĐỀ THI THỬ THPT QUỐC GIA NĂM 2016 MÔN TIẾNG ANH SỐ 6 ĐỀ THI THỬ ĐẠI HỌC MÔN TIẾNG ANH CÓ ĐÁP ÁN