Final answer:
For a mutation to influence evolution, it must happen during the formation of sex cells, allowing it to be inherited by future generations. Germline mutations in gametes are passed to offspring, while somatic mutations can affect the individual but not their descendants.
Step-by-step explanation:
To be important in evolution, a mutation must occur in sex cell formation. This is because mutations in sex cells, which are sperm and ova, can be passed down to future generations, making them evolutionarily significant. Mutations in somatic cells do not get passed to offspring and are not involved in evolutionary changes. Germline mutations that occur in gametes are transmitted to offspring, and every cell in the offspring will contain this mutation.
The majority of mutations are detrimental and can lead to cell death. However, certain mutations may be advantageous by increasing an organism's survival and reproduction within its environment. While mutations are random and unpredictable in occurrence, they can give rise to new genetic material, which is essential for the process of natural selection and consequently, evolution.
Mutations that occur in non-sex cells or somatic cells can lead to other issues, such as cancer. For example, if somatic cells accumulate many mutations, this can result in uncontrolled cell division, which is characteristic of cancerous cells. Unlike germline mutations, these changes are not passed to the next generation but can have significant consequences for the organism in which they occur.