<span>the hydrogen pump may not be functioning properly</span>
        
                    
             
        
        
        
I think it is called  a zygote
        
             
        
        
        
B- black allele; 
b- brown allele;
The parental cross is true-breeding because both the male and the female are homo zygotes, so: BBx bb
The F1 generation will be all black heterozygote: Bb
The F2 generation will be between mice of the F1 generation and they all have the same genotype:Bb xBb
In this cross it would result in:
 1/4 of the plants being black homozygote-BB 25%
2/4 of the plants being black heterozygote- Bb- 50%
1/4 of the plants being  brown homozygote- bb- 25%
answer: 25%+25%=50%  are homozygotes
        
             
        
        
        
Answer: A. The onion cells have lysosomes, and the cheek cells do not.
Explanation: