the extra cell in your blood cells
 
        
             
        
        
        
A dichotomous key is two paired sentences that have contrasting characteristics. That's all i know
        
             
        
        
        
Answer:
The main function of viagra is to relax the muscles of the blood vessels in some areas of the body. It is used for the treatment of erectile dysfunction and for high blood pressure. The component of viagra is a competitor to the enzyme PDE5, breaking down cGMP. In the penis, blood is trapped, which results in the erection being maintained. When cGMP levels decrease, the concentration of calcium ions increases, causing smooth muscle contraction.
Explanation:
 
        
             
        
        
        
Answer:
2. The white patches are caused by the deacetylation of the histones associated with the DNA of the w + allele.
3. The red patches are caused by the acetylation of the histones associated with the DNA of the w + allele.
Explanation:
The complete question is as follows:
How might one explain position-effect variegation in terms ofhistone acetylation and/or deacetylation? Select all thatapply.
1. The white patches are caused by the acetylation of the histonesassociated with the DNA of the w + allele.
2. The white patches are caused by the deacetylation of thehistones associated with the DNA of the w + allele.
3. The red patches are caused by the acetylation of the histonesassociated with the DNA of the w + allele.
4. The red patches are caused by the deacetylation of the histonesassociated with the DNA of the w + allele.
In the W+/W State variegated eye is produced, however in reality the W+ allele causes a red eye colour whereas the W allele causes a white eye.
The reason for production of variegated eyes is chromosomal rearrangement. 
Due to the chromosomal rearrangement the W+ gene's position gets changed and it moves from a region of euchromatin to heterochromatin and this position affect leads to red and white patches in the eye.
The heterochromatin is silent region of the genome which does not encode for any product and this is caused by histone deacetylation whereas the histone acetylation makes the chromosomes more accessible and contributes the euchromatin region.