selection

Question 1

define selection

Answer 1

the process by which organisms that are better adapted to their environment tend to survive and reproduce

Question 2

what are the 2 types of selection

Answer 2

directional selection
stabilising selection

Question 3

define directional selection

Answer 3

individuals with alleles for characteristics towards the extreme of a range are more likely to survive and reproduce

THIS IS DRIVEN BY AN ENVIRONMENTAL CHANGE

Question 4

define stabilising selection

Answer 4

individuals with alleles for characteristics towards the middle of the range are more likely to survive and reproduce.

IN A STABLE ENVIRONMENT

Question 5

explain the process of directional selection through antibiotic resistant bacteria

Answer 5

• there is variation within a population of bacteria
• random mutation results in the production of a new allele of a gene
• this new allele results in the formation of a new protein
• this protein is an enzyme that makes bacteria resistant to a specific antibiotic
• the population of bacteria is exposed to antibiotic
• bacteria with mutation have an advantage as they are more likely to survive and reproduce to pass on the new allele onto offspring
• the population of antibiotic bacteria increases
• this is evolution by selection due to the frequency of the antibiotic resistant allele increasing in the population

Question 6

explain the process of stabilising selection through human birth weight

Answer 6

if babies have a very low birth mass they are less likely to survive
as they have an increased surface to volume ratio therefore it is harder to maintain their temperature so there is increased pressure on heart and lungs

very high birth mass, less likely to survive due to difficulties with giving birth