An enzyme inhibitor is a molecule that binds to an enzyme and decreases its activity. By binding to enzymes' active sites, inhibitors reduce the compatibility of substrate and enzyme and this leads to the inhibition of Enzyme-Substrate complexes' formation, preventing the catalysis of reactions and decreasing the amount of product produced by a reaction.
The child only comes out as homozygous dominant (YY) for the trait in 1/4 boxes in the Punnett Square. This translates to the child having a 25% chance of being homozygous dominant for the trait.
