Evolution

Question 1

Species

Answer 1

A group of organisms that can interbreed to produce a fertile offspring

Question 2

Population

Answer 2

A group of organisms of the same species in a particular space at a particular time
THAT CAN POTENTIALLY INTERBREED

Question 3

2 main sources of variation

Answer 3

Genetic factors
Environmental factors
To change the phenotype

Question 4

Primary source of GENETIC variation

Answer 4

Mutations, create new alleles of a gene

Question 5

When are mutations beneficial?

Answer 5

In a given selection pressure (environmental change), may express a phenotype that benefits possessor to increase chance of survival and therefore reproductive success

Question 6

Genetic diversity

Answer 6

Number of different alleles of genes in a population

Question 7

Other sources of genetic variation other than mutations

Answer 7

Meiosis: independent segregation and crossing over
Random fertilisation of gametes

Question 8

Does the environment impact the phenotype expressed?

Answer 8

Yes

Question 9

Continuous variation

Answer 9

No distinct categories but a quantitative measurement using a scale eg height in cm

Question 10

Continuous variation eg height is controlled by how many genes?

Answer 10

A lot
More than discontinuous variation

Question 11

Is continuous variation strongly influenced by the environment?

Answer 11

Yeah

Question 12

How is variation in continuous characteristics eg height shown on a graph?

Answer 12

Tend to be in line graphs to show how the data is continuous

Question 13

Discontinuos/discrete variation

Answer 13

Has distinct categories like blood type or eye colour
Tends to be qualitative

Question 14

How many genes control discrete variation?

Answer 14

Not many

Question 15

Is discrete variation affected much by the environment?

Answer 15

No

Question 16

Natural selection progression 3 stages

Answer 16

Mutation
Selection pressure
Reproduction + Frequency of beneficial allele increases

Question 17

How does mutation contribute to natural selection?

Answer 17

occurs randomly to create a new allele and increases genetic diversity in a population leading to expression of variety of phenotypes

Question 18

How does a selection pressure contribute to natural selection?

Answer 18

Organisms with alleles provide selective advantages and so more likely to survive and produce offspring + pass on favourable alleles to next generation
Given a selection pressure in environment

Question 19

How does, over time, a species evolve following mutation, selection?

Answer 19

Frequency of beneficial alleles rise in gene pool

Question 20

If beneficial alleles are selected based on advantages, this means species evolve and are……

Answer 20

Adapted to environment

Question 21

Types of adaptations

Answer 21

Anatomical
Physiological
Behavioural

Question 22

Anatomical adaptations

Answer 22

Regarding body parts

Question 23

Physiological adaptations

Answer 23

Regarding body systems

Question 24

3 types of natural selection

Answer 24

Stabilising
Directional
Disruptive

Question 25

Stabilising selection

Answer 25

Selection against both extremes of a phenotype So THE mean phenotype of all species is in the middle of a scale as high frequency of species in population have allele for middle of phenotype

Question 26

Stabilising selection progression

Answer 26

Mutation leads to creation of variety of alleles leads to expression of variety of different phenotypes Selection pressure in environment means advantageous allele for (medium level phenotype) is selected So organisms with this allele more likely to survive and reproduce to pass allele to offspring so this allele increases in frequency in population

Question 27

Case study for stabilising selection

Answer 27

Birth mass in babies: Extreme mass babies more likely to die and less likely to pass on alleles for extreme birth mass to their children So frequency for alleles for extreme mass at birth decreases in population And mid birth mass has selected advantages etc

Question 28

Natural selection

Answer 28

The result of Differential survival and reproduction of specific species due to predation, disease and competition for means of survival Meaning organisms possessing favourable alleles are more likely to survive due to adaptations as a result

Question 29

How does a mutation lead to natural selection?

Answer 29

Creation of new alleles that increases genetic diversity in a population = variety of phenotypes created Organisms with alleles for phenotypes that provide selective advantages are more likely to survive and produce offspring + pass on favourable alleles to next generation. So frequencies of beneficial alleles rise within a gene pool.

Question 30

Frequency of a specific allele in a population shows...?

Answer 30

Proportion of species in a population that possess this allele

Question 31

How are frequencies expressed?

Answer 31

As a decimal out of 1 1.0 = 100% 0.4 = 40% of species in population have this allele

Question 32

Directional selection

Answer 32

Selection in favour of one extreme of a phenotype So mean phenotype of species in this population lies at one extreme end of a scale

Question 33

Progression of directional selection

Answer 33

Mutation leads to creation of alleles for an extreme phenotype Selection pressure in environment means species possessing beneficial extreme allele more likely to survive and reproduce to pass allele onto next gen So frequency of extreme allele thus extreme phenotype in population BOTH INCREASE

Question 34

Case study example for directional selection

Answer 34

Antibiotic resistance in bacteria

Question 35

How does antibiotic resistance occur?

Answer 35

By random mutation, some bacteria have allele for resistance Use of antibiotics is the selection pressure: non-resistant bacteria die; resistant bacteria more likely to survive to reproduce and pass on their alleles Frequency of the resistance allele increases in the bacterial population Frequency of antibiotic resistance increases in the bacterial population;

Question 36

Is natural selection random?

Answer 36

NO based on selected advantages of specific alleles as a result of selection pressure (predation, disease, competition) BUT THE CREATION OF THESE ALLELES BY MUTATION IS RANDOM

Question 37

Disruptive selection

Answer 37

When phenotypes of 2 extremes of a scale are selected for ie selected advantages of 2 alleles that encode for an extreme phenotype

Question 38

Example of disruptive selection

Answer 38

Darker individuals of a species provide more camouflage in shadows but lighter individuals of same species are harder for predators to spot etc

Question 39

Evolution

Answer 39

Change in allele frequencies in a population

Question 40

Allele frequency

Answer 40

The number of times a specific allele occurs in a gene pool

Question 41

Gene pool

Answer 41

All the alleles in a population

Question 42

Genetic drift

Answer 42

RANDOM changes in allele frequency in a population Death that reduces allele frequency by random chance

Question 43

What causes changes in allele frequency thus leads to evolution in a population?

Answer 43

Genetic drift = random changes in allele frequency Natural selection = alleles with selected advantages increase in frequency