Answer:
should be 4
Explanation:
plants cant do photosynthesis without sunlight
Answer:
Your white blood cells are part of the immune system (helps fight off disease) while your red blood cells are part of the circulatory system (transports oxygen and carbon dioxide between the lungs and the rest of the tissues in the human body)
Explanation:
Answer:
balance is another term for it.
Explanation:
Answer:
Scientists believe that the different types we know emerged as early humans adapted to infectious diseases.
Explanation:
Different human blood types probably emerged to ward off infectious diseases. The incompatibility of some blood types, however, is only an "accident" of evolution. But this is a relatively recent problem, since blood transfusion has been around for only a few hundred years.
There are four main blood types. The oldest is B, which must have originated about 3.5 million years ago - it existed even before the human species evolved from its hominid ancestors, from a genetic mutation that modified one of the sugars in the surface of red blood cells.
Approximately 2.5 million years ago, mutations inactivated sugar, resulting in type O blood, which has neither type A nor B. sugar. AB blood, as it is easy to suppose, is covered by both sugar A and sugar by B.
