I think the best phrase to describe this would be Founder effects. Founder effects occurs when a new colony is started by a few members of the original population. This small population size means that the colony may have; a non-random sample of genes in the original population. Reduced variation from the original population.. According to Bottlenecks and founder effects, genetic drift can cause big losses of genetic variation for small populations.
        
                    
             
        
        
        
Answer:
- Oxygen
- The body cells
- Producing energy
Explanation:
We breathe in oxygen from the external environment. Oxygen passes into our lungs and is passed into the blood capilaries.  Here it is carried to all the cells throughout the body. 
It diffuses into the cells and is necessary for the final stages of energy production by aerobic respiration. Therefore, it is necessary for powering all cellular processes. 
 
        
             
        
        
        
Saturation I think not 100% sure sorry
        
             
        
        
        
Human evolution known to be a process in which species adapt to certain
conditions of life, and in the battle of life and death, they are forced
to become stronger in order to survive in this world. Diseases have
always been present during the evolution, acting themselves as a natural
selectors - the weaker organisms get sick and die. Not just humans, but
all species have to establish a great protecting mechanism in order to
survive. That is how our bodies are built, to be able to withstand and
survive in the conditions we live in, and that is why our immune system
has to be taken care of.  
        
             
        
        
        
Answer: A.They contain plants that purify water.