Population and evolution

Question 1

What is a population?

Answer 1

A group of organisms of the same species living in the same space at the same time

Question 2

What is evolution?

Answer 2

A change in allele frequency in a population

Question 3

What is a gene pool?

Answer 3

All of the alleles of all of the genes of all of the individuals of a population

Question 4

What is allelic frequency?

Answer 4

The number of times an allele occurs in the gene pool

Question 5

What does the Hardy-Weinberg principle calculate?

Answer 5

The frequency of the alleles of a particular gene in a population

Question 6

What assumptions does the HWP make?

Answer 6

• Large population
• Isolated population
• No selection
• No mutation
• Random mating

Question 7

What are the two equations used to calculate HWP?

Answer 7

P+q=1 (calculates allele frequency)
P^2 +2Pq+ q^2= 1 (calculates genotype frequency)

Question 8

What does P + q tell you?

Answer 8

Frequency of dominant and recessive allel

Question 9

What does P^2 tell yu?

Answer 9

Frequency of homozygous dominant genotypes in the population

Question 10

What does q^2 tell u?

Answer 10

Frequency of homozygous recessive genotypes in the population

Question 11

What does 2PQ tell u?

Answer 11

Frequency of heterozygous in the population

Question 12

What causes variation in phenotype?

Answer 12

Genetic and enviroment factors

Question 13

Where does genetic variation come from?

Answer 13

• Mutations
• Meiosis
• Random fertilisation of gametes

Question 14

What are mutation?

Answer 14

Changes to genes and/or chromosomes

Question 14

Why doe meiosis produces variation?

Answer 14

Meiosis results in new combinations of alleles in the gametes

Question 15

Why does random fertilisation result in variation

Answer 15

Sexual reproduction results in a new combination of alleles in the offspring. When gametes fuse, introduces further variation

Question 16

How does the environment play a role in genetic characteristics?

Answer 16

The genes set limits on a characteristics. The environment determines where within the limits the organism lies.

Question 17

If we record a polygenic characteristic vs number of population, what would the graph shape be?

Answer 17

Bell shaped

Question 18

What are selection pressures?

Answer 18

Environmental factors which limit the population of a species

Question 19

Examples of selection pressures

Answer 19

Predation
Disease
Competition

Question 20

How does selection pressures link to evolution?

Answer 20

Determine the frequency of alleles in a gene pool

Question 21

What does evolution by natural selection rely on?

Answer 21

Organisms produce more offspring the environment can support.
Their is genetic variety in the population
There are a variety of phenotypes the selection operates against

Question 22

Why is variation important in natural selection?

Answer 22

Variation within a population allows for the selection pressure to change overtime and for the population to evolve and adapt

Question 23

What are three types of selection?

Answer 23

Stabilising
Directional
Distruptive

Question 24

What does stabilising selection favour>

Answer 24

Average

Question 25

What conditions are conductive for stabilising?

Answer 25

Consistent environment, little chang

Question 26

What does directional selection favour?

Answer 26

Individuals with phenotypes on one extreme

Question 27

What conditions are conductive for directional?

Answer 27

A change in the environment which is then consistent

Question 28

What does disruptive selection favour?

Answer 28

Individuals on both extremes

Question 29

What conditions favour disruptive selection?

Answer 29

Vary between two distinct parameters favouring both extremes

Question 30

What is speciation?

Answer 30

Evolution of new species from existing ones

Question 31

What is a species?

Answer 31

Group of individuals with shared ancestry, share the same genes but different alleles and can breed to produce fertile offspring

Question 32

What is the most important factor in speciation?

Answer 32

Reproductive isolation followed by genetic change due to natural selection

Question 33

What are two types of speciation?

Answer 33

Allopatric and sympatric

Question 34

What is allopatric speciation?

Answer 34

Populations separated by a geographical barrier so no gene flow. Mutations cause variation, different selection pressures causes a change in allele frequency and eventually reproductive separation

Question 35

Describe sympatric speciation

Answer 35

Separation within a population such as location or time of mating. No gene flow. Mutation causes variation, different selection pressures change the allele frequency until eventually reproductive isolation

Question 36

What is adaptive radiation?

Answer 36

Process in which organisms diversify from an ancestral species into a multitude of new forms, particularly when exposed to different selection pressures and inhabit different environmental niches

Question 37

What is genetic drift?

Answer 37

Change in allele frequency through generations due to random chance of alleles being inherited. Also due to genetic mutations.

Question 38

Describe a population where genetic drift would have a large impact

Answer 38

Small population.
Small change makes big impact as there are only a small number of different alleles.