UNIT 4 (topic 4) adaption

Question 1

what features must there be for natural selection to occure

Answer 1

• there must be intraspecific variation within population
• there mut be a selection pressure

Question 2

what is the relationship between natural selection and evolution

Answer 2

natural selection id the mechanism by which evolution occurs

Question 3

what points would you include in a paper question

Answer 3

natural variation within the population, selection pressure, type with selective advantage, type selected for and against, differential reproductive success, change in allele frequency

Question 4

what is the differential reproductive success

Answer 4

within a population, some individuals are more likely to reproduce than others

Question 5

what is the allele frequency

Answer 5

how often a specific allele of one gene occurs in the population

Question 6

describe directional selection

Answer 6

selection favours individuals with an extreme phenotype, this is an increase of allele frequency for alleles that produce extreme phenotype

Question 7

how does directional selection change the results of the selection

Answer 7

curve shifts and the mean changes, but not changed shape = same standard deviation and range

Question 8

what sort of environments will directional selection take place

Answer 8

a changing environment - individuals with specific alleles that give extreme phenotype more likely to survive

Question 9

describe stabilising selection

Answer 9

selection against individuals with extreme phenotype, this increases allele frequency for allele that produces mean phenotype

Question 10

how does stabilising selection change the results of the selection

Answer 10

curve narrows and mean remains the same, standard deviation and range decreases

Question 11

in which sort of environment will stabilising selection take place

Answer 11

a stable environment