types of selection

Question 1

what is selection

Answer 1

the process by wich organisms that are better adapted to their enviroment tend to survive and breed

Question 2

what does natural selection alter

Answer 2

allele frequancy

Question 3

what are the two types of selection

Answer 3

directionl selection
satbilising selection

Question 4

define directional selection

Answer 4

where individuals with alleles for characteristics of an extream type are more likely to survive and reproduce

Question 5

what could this directional selection be in response to

Answer 5

an environmental change

Question 6

what is an example of directional selection

Answer 6

antibiotic resistance

Question 7

describe directional selection in relation to antibiotic resistance

Answer 7

some individuals have alleles that give them resistance to an antibiotic. the population is exposed to the antibiotic killing bacteria without the resistant allel

Question 8

what happens to the bacteria that are resistant

Answer 8

resistant bacteria survive and reproduce without competion passing on resistant advantagous allele .
after time most organisms in the population are antibiotic resistant

Question 9

what is stabilising selection

Answer 9

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

Question 10

give an example of stabilising selection

Answer 10

human birth weight

Question 11

describe how human birth weight is a stabilising selection

Answer 11

very small babies when born cannot maintian body temprature and so often die. babies who are too large are also less likey to survive. however favourable medium babies in the middle of the range are favourable and so more likely to survive