Multicellular organisms use different types of cells to function not just one cell. If cells grew larger that cell would be more demanding.
Answer:
they use it to determine whether or not the animal is related by the bone structure and the structure of the body
Basically they just take it into the cell by engulfing it. Once it is inside the cell it is broken down!
<span>the portion of an antigen that binds covalently to an antibody</span>
