3.4.4 Genetic Diversity

Question 1

What is there a variety of if there’s a high genetic diversity

Answer 1

Lots of different alleles

Question 2

What are alleles

Answer 2

Different versions of a single gene

Question 3

Define genetic diversity

Answer 3

The number of different alleles in a species/population

Question 4

2 things that increase genetic diversity in a population

Answer 4

Mutations

Different alleles being introduced

Question 5

What do mutations in dna form

Answer 5

New alleles

Question 6

What’s gene flow

Answer 6

Different alleles being introduced into a population, when individuals from another population migrate into them + reproduce

Question 7

What does genetic diversity allow to occur

Answer 7

Natural selection

Question 8

What reduces genetic diversity

Answer 8

Genetic bottlenecks

Question 9

Define genetic bottleneck

Answer 9

An event that causes a big reduction in a population (die before reproducing )

Question 10

How does a genetic bottleneck cause a decrease in diversity

Answer 10

It reduces number of different alleles in the gene pool

Question 11

What’s a gene pool

Answer 11

Complete range of alleles in a population

Question 12

After a genetic bottleneck, who create a larger population

Answer 12

Survivors reproduce + a few individuals create a larger population

Question 13

What effect is a type of bottleneck

Answer 13

The founder effect

Question 14

What’s the founder effect

Answer 14

What happens when just a few organisms from a population start a new colony with only s small number of different alleles in the initial gene pool

Question 15

What can the founder effect occur due to

Answer 15

Migration -> geographical separation

Question 16

What does natural selection increase

Answer 16

Advantageous alleles

Question 17

What’s natural selection

Answer 17

When some mutations can produce beneficial alleles, helping the organisms survive -> the frequency of this allele will increase

Question 18

2 key factors in evolution

Answer 18

Adaption

Selection

Question 19

What has evolution led to

Answer 19

A huge diversity of species living

Question 20

3 adaptations that help organisms survive

Answer 20

Behavioural adaptations
Physiological adaptations
Anatomical adaptations

Question 21

Example of a behavioural adaptation

Answer 21

‘Play dead’ to escape attack

Question 22

Example of a physiological adaptation

Answer 22

Brown bears hibernate in winter + lower their metabolism, conserving energy

Question 23

Example of an anatomical adaptation

Answer 23

Whales have thick blubber to keep warm

Question 24

2 types of selection that affect allele frequency

Answer 24

Stabilising selection

Directional selection

Question 25

Example of something that shows directional selection

Answer 25

Antibiotic resistance

Question 26

Describe what happens in antibiotic resistance (directional selection)

Answer 26

• some individuals have allele giving them resistance to an antibiotic
• population is exposed to antibiotic, killing any bacteria without the resistant allele
• resistant bacteria survive + reproduce, passing on the allele giving the antibiotic resistance to their offspring
• after some time, most organisms will carry the antibiotic resistance allele

Question 27

How is the mean in the offspring different to the mean in the parent (antibiotic resistance - directional selection)

Answer 27

Mean shifts right in offspring (higher antibiotic resistance)

Question 28

Example of stabilising selection

Answer 28

Human birth weights

Question 29

What’s directional selection

Answer 29

Where individuals for alleles for an extreme type of characteristics are more likely to survive and reproduce. Could be in response to an environmental change

Question 30

What’s stabilising selection

Answer 30

Where individuals with alleles for characteristics towards the middle of the range are more likely to survive and reproduce
It occurs when the environment isn’t changing and it reduces range of possible characteristics

Question 31

Describe human birth weight being an example of stabilising selection

Answer 31

• humans have a range of birth weights
• very small babies are less likely to survive
• giving birth to large babies can be difficult
• conditions are most favourable for middle-sized babies - so wight kg human babies tends to shift towards middle of the range

Question 32

Why are very small babies less likely to survive

Answer 32

They find it hard to maintain their body temperature