4.4 Genetic diversity and adaptation

Question 1

Define genetic diversity

Answer 1

The number of different alleles of genes in a population

Question 2

Reasons for low levels of genetic diversity

Answer 2

• Small population
• Inbreeding

Question 3

Explain the process of natural selection

Answer 3

• A random mutation occurs in one cell, resulting in a new allele in a gene for XXX
• Those with allele are resistant to ZZZ
• YYY provides a selection pressure
• The cell is more likely to survive, and reproduce, passing on allele to offspring
• Over generations, the allele increases in frequency in the population

Question 4

Why is there a time lag on a graph showing resistance?

Answer 4

• Initially, only one individual has the desired allele
• Individuals with allele will survive to produce more offspring
• It takes many generations for the allele to increase in frequency in the population
• Become most dominant

Question 5

What are the types of adaptations that are created by natural selection?

Answer 5

• Anatomical
• Physiological
• Behavioural

Question 6

Explain stabilising selection

Answer 6

• Intermediate phenotypes best adapted to survive in environment
• As intermediate phenotypes are advantageous, they become more common
• Extreme phenotypes disappear

Question 7

Example of stabilising selection

Answer 7

Birth weight in humans

Question 8

Explain directional selection

Answer 8

• Extreme phenotype is best adapted to survive in environment
• As extreme phenotypes are advantageous, they become more common, and intermediate phenotypes disappear

Question 9

Example of directional selection

Answer 9

Antibiotic resistance in rats

Question 10

Describe the procedures for the use of aseptic technique

Answer 10

• Wash hands with soap and disinfect surfaces
• Flame neck of bottle
• Use sterile pipette to transfer bacteria
• Use sterile spreader to spread bacteria
• Place pipette and spreader into disinfectant after use

Question 11

Apart from genetic factors, what other type of factor causes variation within a species?

Answer 11

Environmental

Question 12

Explain how the decrease in spotted owl numbers may affect genetic diversity

Answer 12

• Reduced genetic diversity
• Fewer different alleles

Question 13

What is the purpose of adaptations?

Answer 13

They help organisms to survive and reproduce.

Question 14

What are the 3 types of adaptations?

Answer 14

• behavioural
• anatomical
• physiological

Question 15

What are behavioural adaptations?

Answer 15

Any actions by organisms that help them to survive or reproduce.

Question 16

What are physiological adaptations?

Answer 16

Any internal mechanism features of organisms that help them to survive and reproduce.

Question 17

What are anatomical adaptations?

Answer 17

Structural features of organisms.

Question 18

What is co-adaptation?

Answer 18

The process by which 2 or more species’ phenotypic traits become more closely adapted so that they become dependent on each other.

Question 19

What is genetic diversity?

Answer 19

The number of different alleles of genes in a population.

Question 20

Natural selection can only occur if…

Answer 20

There is genetic diversity within a population.

Question 21

What is natural selection?

Answer 21

The idea that the fittest survive and pass along their traits to their offspring.

Question 22

What is evolution?

Answer 22

Change in allele frequencies over many generations in a population.

Question 23

What is the first stage of natural selection?

Answer 23

New alleles for a gene are created by random gene mutations.

Question 24

What is the second stage of natural selection?

Answer 24

If the new allele increases the chances of the individual to survive in that environment, they are more likely to survive and reproduce.

Question 25

What is the third stage of natural selection?

Answer 25

This reproduction passes on the advantageous allele to the next generation.

Question 26

What is the fourth step of natural selection?

Answer 26

As a result, over many generations, the new allele increases in frequency in the population.

Question 27

What are the 2 types of selection?

Answer 27

Directional and stabilising.

Question 28

What is directional selection?

Answer 28

- One of the extremes has the selective advantage. - Occurs when there is a change in the environment. - Modal trait changes. - ie. The advantageous allele increases in frequency.

Question 29

Summarise directional selection.

Answer 29

Shift in allele frequency to a different (more advantageous) phenotype.

Question 30

What is stabilising selection?

Answer 30

- The modal traits has the selective advantage. - Occurs when there is no change in the environment. - Modal trait remains the same. - Standard deviation decreases.

Question 31

Summarise stabilising selection.

Answer 31

Increase in frequency of the advantageous allele.

Question 32

What is allopatric speciation?

Answer 32

The formation of new species in populations that are geographically isolated from one another.

Question 33

What is sympatric speciation?

Answer 33

A species evolves into a new species without a physical barrier.

Question 34

What is the name of a position of a gene on a chromosome?

Answer 34

Locus.

Question 35

What is meant by genetic diversity?

Answer 35

The number of different alleles present within a gene pool of a species.

Question 36

Describe and explain how selection will have affected the genetic diversity of sugar beet.

Answer 36

- Diversity reduced = fewer different alleles. - As alleles have been chosen.

Question 37

Apart from genetic factors, what other type of factor causes variation within a species?

Answer 37

Environmental.

Question 38

Explain how the decrease in spotted owl numbers may affect genetic diversity.

Answer 38

- Reduced genetic diversity. - As fewer different alleles.

Question 39

What is meant by a quaternary structure?

Answer 39

More than one polypeptide chain.