Gene Pools + Allele frequency revision (2.5)

Question 1

Define allele frequency

Answer 1

Allele frequency is the number of times a particular allele occurs in a population

Question 2

Define evolution

Answer 2

Evolution is the process by which heritable characteristics in a population gradually change over time

Question 3

Define selection pressure

Answer 3

Selection pressure is an abiotic or biotic environmental factor that affects the survival of an individual, and influences the reproduction success in a population

Question 4

Define gene pool

Answer 4

A gene pool is the total number of alleles present in a population

Question 5

Define natural selection

Answer 5

Natural selection is the process by which individuals with traits that make them better suited to the environment tend to survive and reproduce

Question 6

How does natural selection affect the frequency of certain alleles in a gene pool?

Answer 6

• Natural selection causes favourable traits to be selected for, so they become more common in the population over time.
• Unfavourable traits are selected against and tend to be lost in a population.

Question 7

Why is genetic variation in a population important?

Answer 7

• The genetic variation within a species can affect its ability to adapt to an environmental change.
• Populations with greater genetic diversity are more likely to survive environmental changes.
• There is a greater chance that there will be individuals in the population that possess alleles for traits that help them to survive in the new environmental conditions.
• Populations with very low genetic diversity are less likely to survive a change in the environment.
• It is unlikely these populations will have alleles in the gene pool that give certain individuals a survival advantage in the new environmental conditions.
• As a result the population may go extinct.

Question 8

Define adaptative radiation + state an example

Answer 8

• Adaptative radiation is when an ancestral species rapidly evolve into different forms.
• For example, Darwin’s finches have different breaks that make each species well-adapted to their habitat.

Question 9

Define population

Answer 9

A population is the total number of individuals from a species in a particular area

Question 10

Define gene flow

Answer 10

Gene flow describes the movement of genes in and out of a population (immigration + immigration)

Question 11

Define genetic drift

Answer 11

Genetic drift is a random change in the frequency of an allele within a population over time. Genetic drift has a greater effect on smaller populations, and by random chance can eliminate certain alleles.