3.4.4 - Genetic diversity and adaptation

Question 1

what is genetic diversity

Answer 1

genetic diversity is the number of different alleles of genes in a species or population

Question 2

what do alleles code for

Answer 2

alleles code for different versions of characteristics e.g. blonde hair or brown hair

Question 3

what does a large number of different alleles in a population mean there will be

Answer 3

large number of different alleles in a population = large variety of different characteristics = high genetic diversity

Question 4

how can it be a disadvantage if a population has a low genetic diversity

Answer 4

low genetic diversity = may not be able to adapt to change in environment = whole population could be wiped out by single event e.g. a disease

Question 5

how is genetic diversity within a population increased (mutations)

Answer 5

mutations in the DNA forming new alleles. some of these can be advantageous but others can lead to problems

Question 6

how is genetic diversity within a population increased (different alleles)

Answer 6

different alleles being introduced into a population when individuals from another population migrate into it and reproduce (gene flow)

Question 7

what does genetic diversity allow to occur

Answer 7

genetic diversity allows natural selection to occur as some characteristics are more advantageous than others

Question 8

what is a genetic bottleneck

Answer 8

genetic bottleneck is an event that causes a big reduction in a population

Question 9

example of genetic bottleneck

Answer 9

when a large number of organisms within a population die before reproducing

Question 10

what happens as a result of genetic bottlenecks

Answer 10

reduces the number of different alleles in the gene pool and so reduces genetic diversity

Question 11

what happens to survivors after a genetic bottleneck

Answer 11

survivors reproduce and a larger population is created from a few individuals

Question 12

what is the founder effect

Answer 12

founder effect describes what happens when just a few organisms from a population start a new colony and there are only a small number of different alleles in the initial gene pool

Question 13

founder effect: how might frequency of each allele vary in the new colony compared to original population

Answer 13

frequency of each allele in the new colony might be very different to the frequency of those alleles in the original population

Question 14

what can founder effect occur as a result of?

Answer 14

founder effect can occur as a result of migration leading to geographical separation or if a new colony is separated from the original population for another reason e.g. religion

Question 15

what can some mutations produce

Answer 15

alleles that are beneficial to an organism , helping the organism to survive in certain environments

Question 16

what is natural selection

Answer 16

when the alleles code for a characteristic that increases the chances of an organism surviving, its frequency within the population can increase

Question 17

what does natural selection result in

Answer 17

Natural selection results in species that are better adapted to their environment

Question 18

NATURAL SELECTION
step 1

Answer 18

1. not all individuals are as likely to reproduce as each other. there is differential reproductive success in a population

Question 19

NATURAL SELECTION
step 2

Answer 19

2. individuals with an allele that increases their chances of survival are more likely to survive, reproduce and pass on their genes (including the beneficial allele), than individuals with less advantageous alleles

Question 20

NATURAL SELECTION
step 3

Answer 20

3. this means that a greater proportion of the next generation inherits the beneficial allele

Question 21

NATURAL SELECTION
step 4

Answer 21

4. they, in turn, are more likely to survive, reproduce and ass on their genes

Question 22

NATURAL SELECTION
step 5

Answer 22

5. frequency of the beneficial allele in the population increases from generation to generation

Question 23

NATURAL SELECTION
step 6

Answer 23

6. over generations this leads to evolution as the advantageous alleles become more common in the population

Question 24

what is evolution

Answer 24

evolution is the gradual change in species over time

Question 25

what has evolution led to

Answer 25

it's led to the huge diversity of living organisms on Earth

Question 26

what are key factors in evolution

Answer 26

adaptation and selection are key factors in evolution

Question 27

what are adaptations

Answer 27

adaptations are features that help organisms to survive in their environment

Question 28

what are the 3 types of adaptations

Answer 28

- behavioural - physiological - anatomical (structural)

Question 29

what are behavioural adaptations

Answer 29

ways an organism acts that increases its chance of survival

Question 30

give an example of a behavioural adaptation

Answer 30

scorpions dance before mating to make sure they attract a mate of the same species, increasing likelihood of successful mating

Question 31

what are physiological adaptations

Answer 31

processes inside an organism's body that increases its chance of survival

Question 32

give an example of a physiological adaptation

Answer 32

some bacteria produce antibiotics which kill other species of bacteria in the area so there is less competition so they are more likely to survive

Question 33

what are anatomical (structural) adaptations

Answer 33

structural features of an organism's body that increases its chance of survival

Question 34

give an example of an anatomical (structural) adaptation

Answer 34

otters have streamlined shape so easier to glide through water so easier for them to catch prey/escape predators, increasing their chance of survival

Question 35

what are types of natural selection

Answer 35

- directional selection - stabilising selection

Question 36

what do directional and stabilising selection both do?

Answer 36

affect allele frequency in different ways

Question 37

what is directional selection

Answer 37

directional selection is where individuals with alleles for characteristics of an extreme type are more likely to survive and reproduce

Question 38

what directional selection be a response to

Answer 38

this could be in response to an environmental change

Question 39

what is stabilising selection

Answer 39

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

Question 40

when does stabilising selection occur

Answer 40

it occurs when the environment isn't changing

Question 41

what does stabilising selection reduce?

Answer 41

it reduces the range of possible characteristics