4.4. 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 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 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 hem to survive in the presence of antibiotics will reproduce
• Therefore 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

Example of stabilising selection

Answer 9

• Birth weight
• Babies that weigh around 3kg are more likely to survive than those at lower or 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 three types of adaptation?

Answer 11

• Anatomical - changes to body structure
• Physiological - changes to bodily processes
• Behavioural - changes to action

Question 12

Examples of each type of adaptation

Answer 12

• Anatomical - oily fur
• Physiological - venom production
• Behavioural - hibernation