Natural selection act directly upon <u>Alleles</u>
Explanation:
Genes, such as that of fur color, have many variants called alleles. Natural selection act on the alleles and chooses the best fit for an environment and eliminates the disadvantageous ones from the population over generations. Mutations are a rare occurrence that increases the number of allelic variants of a genes on which natural selection can act upon.
Answer;
Endocytosis process
The vesicular process involved in the toxin entering the neuron is endocytosis process.
Explanation;
Endocytosis is a vesicular process, that involves capturing a particle or a substance from the outside of a cell by engulfing it with the cell membrane, and bringing it into the cell.
Botulinum toxin binds to the neuronal cell membranes at the nerve terminus and enters the neuron by endocytosis.