Topic 4: Genetic Information, Variation and Relationships

Question 1

In Africa today, most of the human population are resistant to malaria caused by P. vivax.
Use your knowledge of natural selection to explain why this resistance is so common in Africa (4 marks)

Answer 1

1. Mutation produces allele
2. People with the allele survives and reproduces
3. Allele frequency increases
4. Those with allele resistance less likely to get malaria

Question 2

Mutation can result in an increase in genetic variation within a species.

Describe and explain the other processes that result in increases in genetic variation
within a species. (4 marks)

Answer 2

1. Independent segregation of homologous
   Chromosomes/pairs;
2. Crossing over between homologous
   chromosomes/pairs;
3. Random fertilisation of gametes;
4. (Produces) new combinations of alleles;

Question 3

What is a gene pool? (1 mark)

Answer 3

All the alleles in a population

Question 4

Explain how the use of antibiotics have led to antibiotic resistant strains of bacteria becoming a common cause of infection acquired when in hospital (3 marks)

Answer 4

1. alleles for resistance
2. exposure to antibiotics is selection prssure
3. non resistant bacteria die and resistant reproduce as increased reporductive success
4. increasing frequency of resistant alelle
5. so high frequency of resistant allele
6. more antibiotics used in hospital