They are called paleontologists. 
        
                    
             
        
        
        
Answer:
 I don't think that's a condition, the vacuole is like a storage area so it would make sense for it to store water.
 
        
             
        
        
        
I believe the answer you are seeking is feedback loop
        
                    
             
        
        
        
Answer:
Parental genotypes: RrBb, RRBB
Offspring phenotype: Running and black hair
Explanation:
Given, Running (R) is dominant over waltzing (r)
Black hair (B) is dominant over brown hair (b)
Parent 1: Heterozygous running, heterozygous black = RrBb
Parent 2: Homozygous running, homozygous black = RRBB
When they mate ( RrBb X RRBB ) :
Gametes produced by RrBb = RB, Rb, rB, rb
Gametes produced by RRBB = RB
Offspring:
         RB          Rb         rB        rb
RB   RRBB    RRBb    RrBB    RrBb
All offspring mice will be running mice and will have black hair because all the four types of genotype at least have one dominant allele for both the genes.