Questions: A mutation within a gene always results in a nonfunctional protein. sometimes results in a nonfunctional protein. never results in a nonfunctional protein. always results in a protein with increased function. always results in a new allele.

The answer is the second one: sometimes results in a nonfunctional protein.

Explanation for each option:

1. Always results in a nonfunctional protein: This is incorrect. Not all mutations lead to a nonfunctional protein. Some mutations may be silent (not affecting the protein at all), or they may result in a protein that still retains some or all of its function.

2. Sometimes results in a nonfunctional protein: This is correct. Mutations can sometimes lead to a nonfunctional protein, depending on the nature and location of the mutation. For example, a mutation that causes a premature stop codon or a significant change in the protein's active site can render the protein nonfunctional.

3. Never results in a nonfunctional protein: This is incorrect. Some mutations do indeed result in a nonfunctional protein, especially if they significantly alter the protein's structure or function.

4. Always results in a protein with increased function: This is incorrect. While some mutations can lead to a gain of function, many mutations either have no effect or result in a loss of function.

5. Always results in a new allele: This is incorrect. While a mutation does create a new variant of the gene, not all mutations are significant enough to be considered new alleles, especially if they do not affect the gene's function or expression.

Summary: Mutations within a gene can have various effects, and they sometimes result in a nonfunctional protein, but not always. The impact of a mutation depends on its nature and location within the gene.