ВУЗ:
Составители:
Рубрика:
induce вызывать, побуждать
precipitation (хим.) осаждение
redistribution перераспределение
III. Give the definition of the word “colloid”.
IV. Find the examples of colloids in the text.
V. What does the author mean when he says “the reduction of life
phenomena to a common denominator ”?
VI. Divide the text into several logical parts, give a heading to each of them,
make up a model of the information.
Text 3
I. Read the text and say what it is about.
SOME GENERAL ASPECTS OF OSMOREGULATION IN ANNIMALS
Life began in water, and most probably in sea water. The biochemical
processes sustaining life, and fertilization which perpetuates it, can take place only in
water, and often in water of a specific salt content. The simplest animals living today
are small organisms whose cells are bathed in sea water. From the surrounding sea
water they take their food and oxygen, and to it they return their waste products. In
more complex animals the tissues are no longer in direct contact whit the ambient
medium, but are bathed in blood or some other extracellular fluid. These fluids form
a private pond supplying oxygen and food to the cells and receiving their waste
products. The volume of extracellular fluid is usually much smaller than that of the
cells it surrounds, and in these crowded conditions many complex systems have
developed to regulate the composition of the fluids. Of these regulatory processes,
respiration supplies oxygen and removes carbon dioxide, digestion maintains the
level of nutrients, and osmoregulation controls the volume and composition of the
body fluids. Not only do the excretory organs osmoregulate, but also the body
surface and the gut lining, both of which may transport salt and water between the
environment and the interior of the body. Excretory systems can play only a negative
part in maintaining body fluid concentration, conserving or excreting substances
already present in the blood, but they are unable to add to the blood substances
which are not already present. The activity of the gut and body surface, on the other
hand, can play a much more positive role.
II. Remember the following words and word combinations, consult a dictionary
about the way they are pronounced:
6
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