SORU: aşağıdaki parçaya göre cevaplayınız
What is the passage mainly about?
Mammals have spread successfully over the entire
world, and have even conquered extreme habitats such
as deserts and the Arctic. In spite of all external
diversities, they have numerous characteristics in
common. Mammals are the most highly developed
vertebrate animals. Their constant body temperature
grants them a life largely independent of temperatures
of the surrounding areas. They achieve constant body
temperature by a high food intake ─ in comparison to
reptiles, for example ─ and an increased rate of
metabolism. Long respiration, typical of mammals,
supplies the body cells efficiently with oxygen. The heart
consists of two atria and two ventricles, which are
completely separated from each other. This prevents
the mixing of oxygen-rich and oxygen-deficient blood. All
mammals, except for the egg-laying monotremes, give
birth to live young. During pregnancy, the foetus is
linked to the circulatory system of the female and is
supplied with nutrients via the placenta and umbilical
cord. The exchange of oxygen and carbon dioxide also
takes place using this route.