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 (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. 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

Give an 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 the three 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.