Explain why mutations are important for the long-term survival of a species in a changing environment.

AQA A-Level Biology (7402) — 3.4.3 Mutation and Meiosis · Explain · 5 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Mutations are random changes to DNA. Most mutations have no effect on the organism, but occasionally a mutation produces a new allele that alters the phenotype of an organism.

Model answer (5 marks)

Mutations create new alleles, increasing genetic variation in the population.

When the environment changes, some of these new alleles may give individuals a phenotype better suited to the new conditions.

Those individuals are more likely to survive and reproduce, passing the advantageous allele to their offspring.

Over many generations the frequency of the advantageous allele rises in the population.

Thus mutations provide the raw material for natural selection, allowing a species to adapt and survive long‑term.

Examiner tips

Use the exact terms: allele, phenotype, natural selection, frequency. Show the causal chain from mutation to survival. Keep each point brief but complete. Use the word "increase" for genetic variation.
Mention that the advantage is relative to the new environment.
Use the word "over many generations" to indicate evolutionary time.

Common mistakes

Confusing mutation with natural selection; they are separate processes.
Failing to mention that mutations increase genetic variation.
Using vague language such as "changes" instead of "alleles" or "phenotype".

Mark scheme (5 marks)

Mutations produce new alleles (or new variants of genes)
This increases genetic variation within the population
If the environment changes, some individuals may have a phenotype (caused by the mutation) that is better suited / adapted to the new conditions
Those individuals are more likely to survive and reproduce, passing the advantageous allele to offspring (natural selection)
Over many generations the frequency of the advantageous allele increases in the population, helping the species survive

Key terms in this question

mutation