The structure controls which materiel enter and exit the cell

A

Explanation: A is the cell membrane which is the one that controls what goes in and what goes out

when atoms of different types of elements join together, they make molecules called compounds. water consists of compound molecules made up of 2 hydrogen atoms and 1 oxygen atom. this is why it's called h2o. water will always have 2 times the number of hydrogen atoms as oxygen atoms.

they fuse to form they have half as many chromosomes as a somatic cell of the same individual. b