Answer:
A) respiratory system: gas exchange
Explanation:
The respiratory system's main function is to supply oxygen to all the parts of your body. It accomplishes this through breathing: inhaling oxygen-rich air and exhaling air filled with carbon dioxide, which is a waste gas
DNA replication needs to occur because existing cells divide to produce new cells. ... So the DNA needs to be copied before cell division so that each new cell receives a full set of instructions!
Enzymes are regulated by more than the binding of small molecules. A second method that is used all the time by eucaryotic cells to regulate a protein's function is the covalent addition of a phosphate group to one of its amino acid side chains. These phosphorylation events can affect the protein in two important ways.
