Answer:
The right answer is A
Explanation:
Because animals take in sugar and oxygen, break them down and release carbon dioxide and water along with ATP as usable energy.
Smooth muscles depolarize as a result of a transmembrane current of Calcium ions. When an action potential depolarizes the muscle cell membrane, it also travels into the body of the cell via the t-tubules. Unlike skeletal muscle, smooth muscle is dependent in two sources of calcium in order to intiate contraction. These two sources are calcium sequestered in the S.R. of the smooth muscle cell.
Immune System is the system that consists of proteins and cells.
The answer is A, Viruses
Viruses cannot reproduce on their own , so they have to inject their DNA or RNA into the nucleuus of a cell. By doing this, the virus will take over that cells and within times, that cells will pop up and producing more viruses.
This reproduced virus will repeat the same process until our immune systems stop them
