Genetic diversity and adaptation

Question 1

Define population

Answer 1

All the organisms of a particular species that live in the same place

Question 2

What is an allele?

Answer 2

• Different forms of a particular gene, found at the same locus (position) on a chromosome
• A single gene could have many alleles

Question 3

Define genetic diversity

Answer 3

The total number of different alleles in a population

Question 4

What advantage does a high genetic diversity provide

Answer 4

Ability to adapt to a change in environment; allows natural selection to occur

Question 5

Explain how natural selection results in development of new characteristics

Answer 5

• Random mutations result in new alleles
• Some alleles provide an advantage, making an individual more likely to survive and reproduce
• Their offspring receive the new allele, and frequency continues to increase over many generations

Question 6

What is directional selection?

Answer 6

• Occurs when environmental conditions change
• Individuals with phenotypes suited to the new conditions will survive and pass on their genes
• Over time the mean of the population will move towards these characteristics

Question 7

Give an example of directional selection

Answer 7

• Antibiotic resistance
• Bacteria with a mutation allowing them to survive in the presence of antibiotics will reproduce
• Frequency of this allele will increase and the population will shift to have greater antibiotic resistance

Question 8

What is stabilising selection?

Answer 8

• Occurs when environmental conditions stay the same
• Individuals closest to the mean are favoured, and any new characteristics are selected against
• Results in low diversity

Question 9

Give an example of stabilising selection

Answer 9

• Birth weight: babies that weigh around 3 kg are more likely to survive than those at lower/higher weights

Question 10

Define a niche

Answer 10

• The role of a species within its environment

- Species sharing the same niche will compete with each other

Question 11

What are 3 types of adaptation? Give examples of each

Answer 11

• Anatomical (changes to body structure) e.g. oily fur
• Physiological (changes to bodily processes) e.g. venom production
• Behavioural (changes to actions) e.g. hibernation