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V. Explain the words: symbiotic; algae; honeydew.
VI. On the basis of the text formulate what symbiosis is and illustrate your
statement with some examples.
Text 24
I. Read the text and say what information it carries.
RESPIRATIOH
The essential factor of respiration is an interchange of gases between
protoplasm and the environment: an intake of free oxygen for combustion, and
an outgo of the waste products, chiefly carbon dioxide and water. In the
unicellular organisms, such as Protococcus and Amoeba, and simple
multicellular animals like Hydra, this appears to be a relatively simple process
since an elaborate mechanism is not necessary to facilitate the interchange. But
with the establishment of the highly differentiated multi-cellular body, fewer
cells are- in direct contact with the aerating medium and so various provisions
are necessary to transfer the gases to and from the outer world and the individual
cells themselves.
In all forms the akin functions to some extent; in the Earthworm, in fact it
acts as the chief respiratory membrane since a profuse supply of blood vessels to
the moist surface of the body effects a sufficiently rapid gaseous interchange for
the relatively inactive life of the organism. The Crayfish meets the problem of
respiration by the gills: a method of bathing a large area of the respiratory
membrane in the respiratory medium, the surrounding water. Insects, however,
instead of bringing the blood to the surface, develop a network of tubes, or
tracheae, which ramify throughout the body tissues and conduct air directly to the
cells.
Among the lower Vertabrates, as has been indicated, the anterior end of the
digestive tract functions as common food and respiratory passage. In Fishes, the
respiratory water current which enters the mouth makes its exit by way of the
gill pouches and gill slits, the lining of the pouches functioning as the respiratory
membrane.
II. Remember the following words, consult a dictionary about the way they are
pronounced.
respiration дыхание
intake поглощение, потребление
combustion окисление (органич. веществ)
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