Mutations & Gene Pools Practice Questions

Question 1

How does natural selection contribute to a difference in allele frequency? (4 marks)

Answer 1

• mutations cause variation within the gene pool
• different selection pressures on gene pools exist
• a different allele is favoured over the other
• this allele increases in frequency

Question 2

How does genetic drift differ from natural selection? (2 marks)

Answer 2

• chance occurrence
• more likely in small populations
• no selection pressures

Question 3

What three features are required for natural selection to occur in a population? (3 marks)

Answer 3

• variation
• selective pressures
• reproduction, high birth rate

Question 4

What is meant by a selectively advantageous mutation?

Answer 4

• organisms with mutated gene more likely to survive
• mutated gene provides an advantage over normal one
• individuals with the mutated gene are more likely to reproduce

Question 5

Describe how the link between the sickle cell allele and malaria can lead to changes in the allele frequencies in a population. (4 marks)

Answer 5

• malaria reduces the life expectancy and reproductive potential of an individual
• the sickle cell gene is favoured in malarial prone areas
• those with the trait are more likely to survive and reproduce
• therefore the gene frequency increases

Question 6

How does a gene mutation differ from a chromosomal mutation? (2 marks)

Answer 6

• a gene mutation only affects a single gene, not multiple

- a gene mutation may affect a protein produced