Answer:Valves stop blood flowing backwards
Explanation: Valve are flags of tissue that control the direction of the blood in our heart.,it prevent the backwards flow of blood. valves regulate blood from flowing back into the atria.The right and left atrio-ventricular valves prevent blood from flowing backwards into atria. When the ventricle is full,the valve prevent backwards flow of blood.
Answer:
Carbon dioxide (CO2) and water (H2O)
<span>Blood provides an ideal opportunity for the study of human variation without cultural prejudice. It can be easily classified for many different genetically inherited blood typing systems. Also significant is the fact that we rarely take blood types into consideration in selecting mates. In addition, few people know their own type today and no one did prior to 1900. As a result, differences in blood type frequencies around the world are most likely due to other factors than social discrimination. Contemporary Japan is somewhat of an exception since there are popular Japanese stereotypes about people with different blood types. This could affect choice in marriage partners for some Japanese. </span>All human populations share the same 29 known blood systems, although they differ in the frequencies of specific types. Given the evolutionary closeness of apes and monkeys to our species, it is not surprising that some of them share a number of blood typing systems with us as well. When we donate blood or have surgery, a small sample is usually taken in advance for at least ABO and Rh systems typing. If you are O+, the O is your ABO type and the + is your Rh type. It is possible to be A, B, AB, or O as well as Rh+ or Rh- You inherited your blood types from your parents and the environment in which you live cannot change them. I took it from a website: http://anthro.palomar.edu/vary/vary_3.htm
Metabolism involves the over-all chemical reactions of the body. It is divided into two kinds. The first one is catabolism which is the breaking down of molecules to acquire energy. Anabolism, the other type, is the synthesis of all the molecules that are needed by the cells.
