10. Genetics and Evolution (HL)

Question 1

Definition of the gene pool

Answer 1

The sum total of alleles for all genes present in a sexually reproducing population (must reproduce within the same species)

Question 2

Define allele frequency

Answer 2

The proportion of a particular allele within a population

Question 3

Define Genetic Equilibrium

Answer 3

When all members of a population have an equal chance of contributing to the future gene pool

Question 4

Define Evolution

Answer 4

The cumulative change in the heritable characteristics of a population across successive generations

Question 5

5 Mechanisms of Change/ Different Types of Speciation

Answer 5

1) Mutation: A random change in the genetic composition of an organism due to changes in the DNA base sequence
2) Gene flow: The movement of alleles into, or out of, a population as a result of immigration or emigration
3) Sexual reproduction: Sex can introduce new gene combinations and alter allele frequencies if mating is assortative
4) Genetic drift: The change in the composition of a gene pool as a result of a chance or random event
5) Natural selection: The change in the composition of a gene pool as a result of differentially selective environmental pressures

Question 6

Define reproductive isolation

Answer 6

Occurs when barriers prevent two populations from interbreeding – keeping their gene pools separate

Question 7

What are the 3 reproductive barriers

Answer 7

Temporal, Behavioural and Geographical/Mechanical

Question 8

Define temporal reproductive isolation

Answer 8

occurs when two populations differ in their periods of activity or reproductive cycles

Question 9

Define behavioural reproductive isolation

Answer 9

occurs when two populations exhibit different specific courtship patterns

Question 10

Define geographical/mechanical reproductive isolation

Answer 10

occurs when two populations occupy different habitats or separate niches within a common region

Question 11

Define speciation

Answer 11

Is an evolutionary process that results in the formation of a new species from a pre-existing species

Question 12

Define Allopatric speciation

Answer 12

Formation of 2 different species from one original species, due to geographical isolation

Question 13

Define sympatric isolation

Answer 13

Formation of 2 different species from one original species, due to reproductive isolation (while the populations inhabit the same geographical location)