Unit 2: Key area 2.1 - Drift and Selection

Question 1

Define: Evolution

Answer 1

The process by which different kinds of living organisms are believed to have developed from earlier forms during the history of the Earth.

Question 2

Define: Species

Answer 2

A species is a group of populations that can interbreed in nature.

Question 3

Define: Genetic Drift

Answer 3

The changes seen in the alleles of a population due purely to chance

Question 4

Define: Neutral Mutations

Answer 4

Mutations that do not give a selective advantage or disadvantage therefore subject to genetic drift.

Question 5

Define: Bottleneck Effect

Answer 5

Occurs when there is a disaster of some sort that reduces a population to a small handful which rarely represents the actual genetic makeup of the initial population.

Question 6

When does the founder effect occur?

Answer 6

Occurs when there is a lack of genetic variation due to a small mating population.

Question 7

Both bottleneck effect and founder effect provide an opportunity for what evolutionary process to take over?

Answer 7

Genetic Drift

Question 8

Define: Carrying Capacity

Answer 8

The population that can be sustained by a particular environment

Question 9

Define: Natural Selection

Answer 9

The differential survival and reproduction of individuals due to differences in phenotype

Question 10

When population growth takes the population above the carrying capacity, this leads to what, to alter the carrying capacity?

Answer 10

Environmental Change

Question 11

List four living changes that could take place in an ecosystem to reduce population in an environment?

Answer 11

1. Migration 2. Competition 3. Disease 4.Change of Species

Question 12

List two abiotic (non-living) changes that could take place in an ecosystem to reduce population in an environment?

Answer 12

1. Climate changes 2. Geological processes - tectonic plate movement

Question 13

Changes in the ecosytem cause some organisms to struggle for surivial this is known as

Answer 13

selective pressure

Question 14

Evolution can occur through what three processes?

Answer 14

Genetic drfit, Natural Selection and Sexual Selection

Question 15

Define Genetic drift:

Answer 15

Random change in how frequently a particular allele occurs within a population

Question 16

Does genetic drift have a bigger or smaller effect on small gene pools?

Answer 16

Bigger

Question 17

Why do certain alleles occur more frequently within a population?

Answer 17

Because they confer a selective advantage

Question 18

Alleles that offer an advantage occur more frequently becasue they?

Answer 18

Increase the chance that the individuals can compete and survive to pass the advantageous allele on to future generations.

Question 19

Novel alleles arising in a situation is usually due to?

Answer 19

Random mutaiton

Question 20

Fitness can be measured in two terms which are?

Answer 20

1. Absolute fitness 2. Relative fitness

Question 21

Define: absolute fitness

Answer 21

Ratio of frequencies of a particular genotype from one generation to the next.

Question 22

If the absolute freqency of an genotype is 1, then?

Answer 22

The frequency of the genotype is stable

Question 23

A value greater than 1 in the absolute fitness conveys an

Answer 23

Increase in the genotype

Question 24

A value less than 1 in the absolute fitness conveys a

Answer 24

decrease in the frequency of a genotype

Question 25

Define: Relative Fitness

Answer 25

Ratio of surviving offspring of one geotype compared with the other genotype

Question 26

Purple pea plants are the most reproductively successful so have a relative fitness of one, white pea plants are only 65% as successful so have a relative fintess of ?

Answer 26

0.65