Natural selection at the genetic level | Exit Quiz | Oak National Academy

Mutations occur …

• at random.

• deliberately to help organisms to evolve.

• only when organisms need to evolve.

Answer explanation

Evolution does not plan ahead. Mutations happen at random. When they create advantageous genetic variants, these are more likely to be passed on due to natural selection.

Mutations create genetic variants. Who has the correct idea about genetic variants?

• 
• 
• 
• 

Answer explanation

A genetic variant may change an organism’s phenotype (its traits) in a way that is advantageous, harmful, or neither.

Match the start of each sentence to its correct ending.

• No genetic variants …

• change the organism’s phenotype.

• Some genetic variants …

• happen due to evolution.

• All genetic variants …

• change the organism’s genome.

Answer explanation

Evolution happens because of genetic variants, not the other way around. All genetic variants change the organism’s genotype because the DNA base sequence has changed; the phenotype is only changed if the activity of the protein made is changed.

Because of natural selection, genetic variants that code for advantageous traits …

• become less common over generations.

• become more common over generations.

• do not change frequency over generations.

Answer explanation

Natural selection causes advantageous traits to become more common over generations because individuals with those traits are better adapted to survive and pass the genetic variants on to the next generation.

Put the statements in the correct order to explain why the genetic variant that codes for black colouration in the peppered moth became more common when tree bark darkened.

• Individuals with the genetic variant were more likely to pass it onto offspring.

• This repeated over many generations.

• Individuals with the genetic variant were more likely to survive and reproduce.

• Individuals with the genetic variant were better adapted to their environment.

Answer explanation

Natural selection causes advantageous traits to become more common over generations because individuals with those traits in each generation are better adapted to survive and pass the genetic variants on to the next generation.