Genetic diversity and adaptation Flashcards

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1
Q

Define population.

A

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

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2
Q

What is an allele?

A

Different forms of a particular gene, found at the same locus (position) on a chromosome.

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3
Q

Define genetic diversity.

A

The total number of different alleles in a population.

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4
Q

What advantage does a high genetic diversity provide?

A

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

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5
Q

Explain how natural selection results in development of new characteristics.

A

● 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.

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6
Q

What is directional selection?

A
  • 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.
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7
Q

Give an example of directional selection.

A

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.

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8
Q

What is stabilising selection?

A

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.

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9
Q

Give an example of stabilising selection.

A

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

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10
Q

Define a niche.

A

The role of a species within its environment.

Species sharing the same niche will compete with each other.

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11
Q

What are the three types of adaptation? Give examples of each.

A

● 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.

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