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 and are able to produce fertile offspring

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

Define the advantage to a higher number of alleles in a population

Answer 4

The greater the number of alleles in a population, the greater the genetic diversity, and therefore the greater the chance that a population would survive a change in their habitat

Question 5

What advantage does a high genetic diversity provide?

Answer 5

The ability to adapt to a change in the environment; allows natural selection to occur

Question 6

Explain how natural selection results in development of new characteristics

Answer 6

• 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 7

What is selection?

Answer 7

Selection is the process by which individuals that are better adapted to their environment are more likely to survive and breed. This means that they can pass on their advantageous alleles. Every living organism is subject to selection determined by the conditions which they are living in

Question 8

Name the two key types of selection?

Answer 8

Directional and stabilising

Question 9

What is directional selection?

Answer 9

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

Question 10

Give an example of directional selection

Answer 10

Antibiotic resistance - bacteria with a mutation allowing them 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 11

What is stabilising selection?

Answer 11

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 12

Give an example of stabilising selection

Answer 12

Birth weight - babies that weigh around 3kg are more likely to survive than those at lower or higher weights

Question 13

Define a niche

Answer 13

The role of a species within its environment. Species sharing the same niche will compete with each other

Question 14

What are the three types of adaptation?

Answer 14

• Anatomical
• Physiological
• Behavioural

Question 15

Give an example of an anatomical adaptation

Answer 15

Changes to body structure, e.g. oily hair

Question 16

Give an example of a physiological adaptation

Answer 16

Changes to bodily processes, e.g. venom production

Question 17

Give an example of a behavioural adaptation

Answer 17

Changes to actions, e.g. mating calls