Protein can be found in every living cell and it is very
important building block in the body. Protein supply amino acids which were
being used to create and repair cells, enzymes, red blood cells, antibodies and
tissues. In the body, protein functions by maintaining fluid balance and
transportation substances. Protein can be gotten from meat, dairy products, soyabeans,
nuts, beans and certain grains. However,
protein from meat and other animal products are known as complete protein.
Involuntary functions of the body system; processes taking place in the body that is done without conscious efforts such as digestion, bloodflow, the heartbeat are controlled by the autonomic nervous system which is a part of the peripheral nervous system.
Natural selection occurs when one allele (or combination of alleles of different genes) makes an organism more or less fit, that it is able to survive and reproduce in a given environment. If an allele reduces fitness, its frequency will tend to drop from one generation to the next.
It is the basic unit of energy for all functions of the cell without ATP the ions wouldn't be able to transport across the cell membrane. I hope this helps!