I found the attached image on the internet and it really helps complete this exercise.
First question:
In the presence of an enzyme, the course of the reaction is shown by the
red curve. The necessary energy to make a reaction occur is less when there is an enzyme to help the reaction happen. Enzymes work as catalysts that act over substrates converting them into different molecules in a much accelerated way then it would happen without the enzyme's help, if it would happen at all.
Second question:
The activation energy is represented by
line B. The activation energy is the energy needed to be available for a reaction to happen. If we compare it with line A, which represents the activation energy necessary for a reaction without an enzyme, we can see how much less energy is necessary to dispend when an enzyme is part of the reaction. Line C represents the energy resultant from the reaction.
Answer:
Frequency of the B3 allele 
Explanation:
The allele frequencies in a given population remain constant which means that every generation will have the same gene pool across the generations. As per Hardy Weinberg’s first equilibrium equation, the sum of frequency of all the alleles at a given locus is equal to one
Thus, if "p" represents the frequency of B1 allele and "q" represents the frequency of B2 allele and "r" represents the allele for B3 allele. Then, sum or "p", "q" and "r" is equal to one.

Substituting the given values, we get -

Tetanic contractions might happen, which would lead to the heart to stop pumping