Genetic diversity

Question 1

Natural selection

Answer 1

The process by which the frequency of ‘advantageous’ alleles gradually increases in a population’s gene pool over time.

Question 2

Evolution

Answer 2

A change in allele frequency overtime

Question 3

Stabilising selection

Answer 3

A type of selection that favours individuals close to the mean, maintaining the traits of the population.

Question 4

Selection pressure

Answer 4

An external factor that influences the reproductive success of an individual.

Question 5

Example of Selection pressure

Answer 5

Disease acts as a selection pressure that increases the reproductive success for individuals who are immune to the disease.

Question 6

In what type of enviroment does stablising selection take place in

Answer 6

An enviroment that does NOT change

Question 7

Example of stablising selection

Answer 7

Human birth rate.

• If a baby has a below average weight, it is unlikely to survive.
• If a baby has an above average weight, it is more likely to encounter difficulties during birth.

Question 8

Directional selection

Answer 8

The process where natural selection favours an extreme phenotype

Question 9

When does directional selection take place?

Answer 9

After an environment has experienced a change.

Question 10

Example of Directional selection

Answer 10

Antibiotic resistance
If bacteria are exposed to antibiotics, most of the population will not be resistant to its effects and will not survive.
If a mutation evolved that confers resistance, selection will strongly favour bacteria with the resistant phenotype.

Question 11

What phenotype is favoured in bacterial populations that are exposed to antibiotics?

Answer 11

Antibiotic resistance

Question 12

What type of environment does stabilising selection take place in?

Answer 12

Non-changing

Question 13

Describe how an adaptation, such as better running speed, relates to natural selection.

Answer 13

Natural selection reproduces individuals with favourable genetic traits-such as adaptation of better running speed-over time

Question 14

Adaptions

Answer 14

A feature of an organism that increases its chance of survival in its environment. An adaptation may be anatomical, physiological or behavioural.

Question 15

Anatomical adaptations

Answer 15

Physical structures that have evolved to increase the chance of survival.

Question 16

Examples of Anatomical adaptations

Answer 16

The long neck of giraffe - Allows them to get food easily

Blubber - Insulates Walruses. helps them prevent heat loss

Question 17

Physiological adaptations

Answer 17

are processes within the body that have evolved to increase the chance of survival.

Question 18

Examples of Physiological adaptations

Answer 18

• Venom produced by some snake species (e.g. the black mamba) is a physiological adaptation.
• to protect them from potential predators which increases their chance of survival.
• Shivering is a physiological adaptation.
  Mammals have evolved to shiver in cold environments.
  Shivering helps maintain body temperature within optimum range

Question 19

Behavioural adaptations

Answer 19

actions that have evolved to increase the chance of survival.

Question 20

Example of Behavioural adaptations

Answer 20

Hunting of cheetahs’s - The stalking behaviour increases the chance the cheetah will successfully catch a prey.

Spider webs - Increases the chance the spiders will survive because they can catch food more easily.

Question 21

Snake venom is an example of what type of adaptation?

Answer 21

A physiological adaptation

Question 22

Aseptic techniques include:

Answer 22

Disinfect surfaces.
Sterilise equipment to destroy microorganisms.
Flame the necks of bottles on opening.

Question 23

What is the zone of inhibition?

Answer 23

Zone where no bacteria grow

Question 24

Stages involved in investigating Microbial growth:

Answer 24

1. Make sure the conditions for experiment are aseptic
2. Spread the bacteria onto a petri dish
3. Place antibiotic ring on the petri dish
4. Place lid on the petri dish and loosely secure the lid with tape
5. Incubate the petri dish upside down for 24-48 hours
6. Observer the growth pattern of bacteria

Question 25

Why should you make sure your conditions for the experiment are aspect?

Answer 25

To prevent the growth of any unwanted microorganisms that might affect the results

Question 26

Why should you use a pure culture of bacteria?

Answer 26

To make a lawn spread on a petri dish

Question 27

Why should you secure the petri dish loosely with tape?

Answer 27

To allow the flow of oxygen and prevent the growth of anaerobic bacteria

Question 28

Why should you incubate the petri dish upside down?

Answer 28

To prevent condensation from dripping onto the agar

Question 29

OBSERVE GROWTH PATTERNS

you should a zone of inhibition around the antibiotic ring where no microorganisms have grown. What should you do?

Answer 29

Measure of zone of inhibition

Question 30

What can inferred from there being a greater number of different alleles in a population

Answer 30

A greater genetic diversity in that population

Question 31

What are two ways in which genetic diversity in a population is increased?

Answer 31

Mutations

Gene flow

Question 32

The presence of genetic variation in a population allows what process to take place

Answer 32

Natural selection

Question 33

What is the name of the process in which natural selection favour an extreme phenotype

Answer 33

Directional selection

Question 34

What should be seen after incubation when investigating the effect of anti microbial substances on the growth of microorganisms?

Answer 34

No organisms growth around the antibiotic ring

Question 35

What type of selection takes place in environments that do not change

Answer 35

Stabilising