Question

which of the following mutations would most likely have a harmful effect on an organism?
a deletion close to the end of the gene.
a deletion near the middle of the gene.
a deletion near the beginning of the gene.
a substitution.

Explanation:

A deletion near the beginning of a gene would disrupt the reading frame early. This leads to a non - functional protein as most of the amino acids downstream will be incorrect. A substitution is often less harmful as it may only change one amino acid (if it's a missense mutation) or have no effect (if it's a silent mutation). Deletions near the middle or end also disrupt the reading frame but have less of the gene affected compared to a deletion at the beginning.

Answer:

a deletion near the beginning of the gene.