When an enzyme exceeds the typical human body temperature, the enzyme's structure can denature and change - therefore the enzyme won't function properly.
The enzyme structure begins to break down
intermolecular bonds are broken
enzyme molecules gain kinetic energy.
Explanation;
Enzymes are proteins that play an important function in the body of catalyzing reactions in the body.
Enzymes work best at optimum temperature; low temperature lower than optimum temperatures deactivates them and higher temperature denatures them.
The shape of an enzyme depends on its temperature; when they get too warm they get loose, and at very low temperatures they get too tight. At optimum temperature or at the right temperature then they are just at the right shape and the chemical reactions they catalyze will be at optimal rate.
The horse will give 32 chromosomes and donkey will give 31 chromosomes to the offspring. The offspring has 63 in total. It is odd so it can not produce normal germ cell. So it is sterile.