natural selection

Question 1

what is natural selection

Answer 1

the process that drives evolution which is the change in the frequency of a gene in a population

Question 2

how do mutations cause evolution

Answer 2

mutations are a change in the dna base sequence and so new alleles of a gene are produced which can be beneficial

individuals with the advantageous alleles are more likely to survive and reproduce

as mutations are heritable, they will be passed to offspring

over time the allele frequency will increasing leading to evolution and increased genetic diversity

Question 3

describe stabilising selection

Answer 3

this is when the average phenotype is favoured and occurs when there is no change in the enviornment
this leads to a narrower curve on a graph

Question 4

describe directional selection

Answer 4

an extreme phenotype is favoured and so they are more likely to survive and reproduce
this occurs when there is a chnage in the enviornent and cuases a shift over time

Question 5

how do bacteria become resistant to antibiotics

Answer 5

some can develop a mutation which provides antibiotic resistance
when antibiotics are used, only the non resistant ones are killed
these bacteria will then go on to survive and reproduce passing down their alleles
over time the allele frequncy will increase for antibiotic resistance