Exam 3 (Mutation)

Question 1

What is a mutation?

Answer 1

A mutation is a change in the DNA sequence of a gene. It can happen randomly or due to environmental factors, and it may affect how proteins are made—sometimes causing traits to change.

Question 2

What types of substances or energy can cause mutations?

Answer 2

Mutations can be caused by:

Radiation (like UV light, X-rays)

Chemicals (like tobacco smoke, asbestos, or pollution)

Viruses (like HPV)

Errors during DNA replication (random mistakes)

These are called mutagens—things that can damage or alter DNA.

Question 3

What are examples of positive and negative mutations?

Answer 3

Positive Mutation Example:
Lactase persistence
– A mutation near the LCT gene lets some people digest lactose into adulthood.
– Helps survival in dairy-farming cultures.

Negative Mutation Example:
Cystic fibrosis
– Caused by a mutation in the CFTR gene.
– Leads to thick mucus in lungs and digestive problems.

Question 4

What is the effect of mutation on the diversity of a population?

Answer 4

Mutations increase genetic diversity by creating new alleles.

This adds variety to the gene pool.

Some mutations may lead to advantageous traits, which natural selection can favor.

Others may be harmful or have no effect.

Overall, mutations are the original source of all genetic variation in a population.

Question 5

How is mutation related to other sources of evolution?

Answer 5

Mutation is the starting point for evolution because it creates new alleles. These new alleles can then be acted on by other forces of evolution:

Natural Selection – picks helpful mutations that improve survival or reproduction.

Genetic Drift – may randomly increase or remove mutated alleles, especially in small populations.

Gene Flow – can spread mutated alleles between populations.

Non-random Mating/Inbreeding – affects how mutations get passed on.

👉 Without mutation, there would be no new genetic variation for evolution to work with.