Answer:
This is true.
Explanation:
More commonly, an X chromosome will die and get replaced by a Y chromosome (all humans start off as females). When this occurs, the substitute Y chromosome causes changes in the zygote to occur; they begin developing male genitalia (i.e. penises, testicles, prostates, etc.).
 
        
             
        
        
        
I think it is fossil fuel .. might be wrong tho
 
        
             
        
        
        
Answer:
The flow of individuals in and out of a population introduces new alleles and increases genetic variation within that population. Mutations are changes to an organism's DNA that create diversity within a population by introducing new alleles.
Explanation: