4.4 - Genetic diversity and adaptations

Question 1

Define genetic diversity

Answer 1

total number of different alleles of each gene in a population

Question 2

Describe the relationship between genetic diversity and natural selection

Answer 2

genetic diversity is a factor enabling natural selection to occur

Question 3

Describe the principles of natural selection

Answer 3

• change in selection pressure causes random mutation, which can result in new alleles of a gene
• individuals with mutation more likely to survive and reproduce
• advantageous allele inherited by members of the next generation
• over many generations/time, allele frequency increases in population (leading to evolution)

Question 4

What is stabilising selection and give an example

Answer 4

favours average phenotype
e.g human birth weights

Question 4

What is directional selection and give an example

Answer 4

favours 1 extreme phenotype
e.g antibiotic resistance in bacteria

Question 5

Types of adaptations caused by natural selection

Answer 5

• anatomical: physical structures
• physiological: processes within the body
• behavioural: actions (can be learnt or inherited)

Question 6

What is the Founder effect?

Answer 6

• when a small number of individuals from a large parent population start a new population
• so small gene pool

Question 7

Define gene pool

Answer 7

complete range of allele that exist in all the individuals of a population or species

Question 8

Define genetic drift

Answer 8

gradual change in allele frequencies in small population due to chance (not natural selection)

Question 9

Define genetic bottleneck

Answer 9

• when a previously large population suffers a dramatic fall in numbers e.g by a natural disaster
• reduces genetic diversity in population as alleles are lost
• surviving individuals breed and reproduce with close relatives