4.4 Genetic variation and adaption

Question 1

What is genetic diversity?

Answer 1

the total number of different alleles in a population

Question 2

What is an advantageous allele?

Answer 2

an allele that provides a phenotype favourable for the environment that will increase survival chances

Question 3

What is the advantage to genetic diversity?

Answer 3

orgs are less vulnerable to environmental changes = as there is a chance at least 1 org will have a phenotype favourable to the new environment

Question 4

What 3 things increase biodiversity between populations?

Answer 4

natural selection
genetic drift (7.3)
mutation

Question 5

What decreases genetic diversity between populations?

Answer 5

gene flow

Question 6

How does natural selection increase genetic diversity between pops?

Answer 6

the same species but different pops
the pops experience diff environments = exposed to different selection pressures

Question 7

What 2 things increase genetic diversity within a population?

Answer 7

gene flow and mutation

Question 8

What 3 things decrease genetic diversity within a population?

Answer 8

natural selection
genetic drift (7.3)
interbreeding

Question 9

How does natural selection decrease genetic diversity within a pop?

Answer 9

the favoured phenotype for survival is dominant

Question 10

What is the process of natural selection?

Answer 10

a random mutation occurs = gives orgs survival advantage = increases genetic variation
change occurs in a stale environment
competition/ predation and disease are selection pressures
orgs without favourable allele do not survive
orgs survive and breed
new allele passed onto the next generation
new allele increases in frequency

Question 11

What is evolution?

Answer 11

the change of the allele frequencies in a population over time

Question 12

What are selection pressures?

Answer 12

any environmental pressure that limits the population or kills individuals

Question 13

What is an example of a selection pressure?

Answer 13

the use of antibiotics on bacteria develops a resistance

Question 14

What are the 3 types of adaptations?

Answer 14

anatomical
behavioural
physiological

Question 15

What are anatomical adaptations?

Answer 15

structural feature eg = shape of a beak of a bird

Question 16

What are physiological adaptations?

Answer 16

different chemical reactions in the body eg = quantity and types of enzymes

Question 17

What are the 3 types of selection?

Answer 17

stabilising selection
directional selection
disruptive selection (7.3)

Question 18

What is stabilising selection?

Answer 18

preserves the average phenotype
selects against extreme phenotypes
occurs in a stable environments

Question 19

What is an example of stabilising selection?

Answer 19

human birth weight = too low or too high can be unhealthy

Question 20

What is directional selection?

Answer 20

favours 1 extreme phenotype = has a selective advantage
populations characteristics change
occurs when the envrionment changes

Question 21

What is an example of directional selection?

Answer 21

anitbiotic resistance in bateria = selective advantage favoured

Question 22

How does antibiotic resisance develop in bacteria?

Answer 22

1. use of antibiotics = selection pressure
2. new allele resistant to antibiotics develops via mutation
3. new phenotype increases survival - genes passed on
4. binary fission of resistant bacteria
5. increase allele freq of antibiotic resistant bacteria over many gens of binary fission

Question 23

What are aseptic techs used for investigating antibiotic affects on bacteria?

Answer 23

wipe surfaces with antibacterial cleaner - before and after
bunsen burner = convection current draws microbes away from culture
flame wire loop
flame neck of any bottles = prevents bacteria entering vessel
open bottles and petri dish for minimum time poss
close windows and doors

Question 24

What is the method of investigating affects of antibiotics on bacteria?

Answer 24

1. aseptic techs
2. wire loop used to transfer bacteria from broth to agar plate
3. spread bacteria evenly using sterile plastic spreader
4. use sterile forceps - ass multi disc antibiotic ring on plate
5. tape lid on, invert and incubate at 25`C for 48hrs
6. sterilise equipment and disinfect work surfaces

Question 25

Why shouldnt you tape the whole lid on a perti dish?

Answer 25

prevents oxygen entering = growth of harmful anaerobic bacteria

Question 26

Why isnt bacteria incubated at 37`C?

Answer 26

incubated at 25`C to prevent the growth of pathogens harmful to humans