Answer:
Water, carbon dioxide, and oxygen are among the few simple molecules that can cross the cell membrane by diffusion (or a type of diffusion known as osmosis ). Diffusion is one principle method of movement of substances within cells, as well as the method for essential small molecules to cross the cell membrane.
 
        
             
        
        
        
Answer:
1. A  2.B  3.B 4.C 6.A 7.B 8.C 9.D
Explanation:
 
        
             
        
        
        
It would be 2) two atoms exchange electrons and become ions
        
             
        
        
        
The proteins have 3 limbs one is brown one is purple and the other is green. Phenotypes are the are the contrasting color there for they make the organism work.