A donkey and a horse can be mated to produce a mule, but mules are sterile and cannot have offspring. Infer whether donkeys and horses should be considered the same species. Explain
your answer using textual evidence.

But hinnies and mules can't have babies of their own. They are sterile because they can't make sperm or eggs. They have trouble making sperm or eggs because their chromosomes don't match up well. ... A mule gets 32 horse chromosomes from mom and 31 donkey chromosomes from dad for a total of 63 chromosomes

this transfer is call conjunction

enzyme active site and substrate specificity

enzymes bind with chemical reactants called substrates. there may be one or more substrates for each type of enzyme, depending on the particular chemical reaction. in some reactions, a single-reactant substrate is broken down into multiple products