Answer:
Oxygen was not present on early earth
Answer:
It is a mixture
Explanation:
It is a mixture because a mixture contains tow or more elements
But a compound is made up of atoms
The proteins in the cell membrane allow the nutrients to go and waste to go out <span>of a cell. Water passes through the cell membrane without the help of proteins.</span>
Protects brain and spinal cord from trauma, as well as supplies nutrients to nervous system tissue. It also removes waste from cerebral metabolism.
