Mutations

Question 1

gene pool

Answer 1

Gene pool is the sum of all alleles possessed by an entire population at any one time
Within this gene pool,

Question 2

how are allele freuqncies calcualted

Answer 2

the allele frequencies of ‘A’ and ‘a’ and be determined:

(𝑁𝑜. 𝐷𝑜𝑚𝑖𝑛𝑎𝑛𝑡 𝑎𝑙𝑙𝑒𝑙𝑒𝑠 (𝐴))/(𝑡𝑜𝑡𝑎𝑙 𝑎𝑙𝑙𝑒𝑙𝑒𝑠) 𝑋 100

(𝑁𝑜. 𝑟𝑒𝑐𝑒𝑠𝑠𝑖𝑣𝑒 𝑎𝑙𝑙𝑒𝑙𝑒𝑠 (𝑎))/(𝑡𝑜𝑡𝑎𝑙 𝑎𝑙𝑙𝑒𝑙𝑒𝑠) 𝑋 100

Question 3

increased genetic diversity.
is achieved hwo

Answer 3

The larger and more diverse gene pool will contain a greater variety of gene and alleles, resulting in increased genetic diversity.

Question 4

What is a mutation?

Answer 4

A mutation is a permanent change in the DNA sequence.

Question 5

What is an advantageous mutation?

Answer 5

An advantageous mutation provides a selective advantage over other phenotypes, helping an organism survive and reproduce.

Question 6

hat is a neutral mutation?

Answer 6

A neutral mutation has no effect on the amino acid sequence and is often referred to as a silent mutation.

Question 6

What is a deleterious mutation?

Answer 6

A deleterious mutation can cause disease or reduce an organism’s fitness.

Question 7

What are some common causes of mutations?

Answer 7

Mutations can be caused by mutagens such as UV rays, X-rays, chemicals, or occur spontaneously.

Question 8

How are mutations inherited?

Answer 8

For mutations to be inherited, they must occur in germline cells (sperm or egg cells).

Question 9

The effect of mutations on allele frequencies

Answer 9

Mutations introduce new alleles to a gene pool
Passing this down to offspring will increase the allele frequency and overtime may replace another allele if it is beneficial.

Question 10

types of mutatin=ons

Answer 10

point mutaitons
frameshift mutations
silent mutations

Question 11

Point mutations

Answer 11

Changes to one nucleotide in a gene due to substitution. Can be classified as:
silent, missense, nonseense

Question 12

Silent vs missense vs nonsense mutation

Answer 12

Silent mutation is where one nucloetide is substituted for another, the gene still codes for the same amino acid sequence, this is dueto the degeneracy of the geneitc code and has no effect on the protein produced

Missense mutation is were one nucletoide is substituted foranother, resulitng in a differnet seuquecne of amino acids. A differnet protein is produced

Nonnesnse mutation:
one nucleotide is susbitied for anotherto a nucleotide that results prematurely ending translation due to a codon becoming the STOP codon. Protein is shorter than the regular protein. and protein is not functional

Question 13

Frameshift mutations what is it and examples

Answer 13

Involves the addition or deletion of one or two nucleotides. This results in a ‘shift’ in how the DNA strand is read,Amino acid sequence changes which also results in a change in protein.

Cystic fibrosis, Crohn’s disease and certain types of cancers are due to frameshift mutations

Question 14

explain the types of frameshfit mutation, framshefit insertion and deletion

Answer 14

Frameshift mutation (insertion)
Addition of one or two nucleotides which alter the reading frame of the following nucleotides.

Frameshift mutation (deletion)
Deletion of one or two nucleotides which alter the reading frame of the following nucleotides.

Question 15

Block mutations

Answer 15

Involve the altering the structure of a chromosome by inserting, deleting or swapping a cluster of nucleotides during meiosis.
Can impact multiple genes

Question 16

Chromosomal abnormalities -

Answer 16

Aneuploidy and polyploidy

Question 17

aneuploidy wat is and examples

Answer 17

AneuploidyAneuploidy occurs when an individual has an extra chromosome or one missing in their karyotype.

Aneuploidy occurs when an individual has an extra chromosome or one missing in their karyotype.

Question 18

Polyploidy

Answer 18

Occurs when an individual has more than two sets of chromosomes
In humans, zygote is unable to survive
In plants, can result in an altered phenotype

Question 19

allele what is it

Answer 19

pair of genes that occupy a specific location on a particular chromosome and control the same trait

Question 20

mutagen

Answer 20

Anything that can cause a mutation

Question 21

tNatural Selection

Answer 21

A mechanism for evolution in which the individuals best adapted to the selection pressures in their environment survive and pass on their alleles to their offspring.

Question 22

types of block mutations and explain

Answer 22

deletion bock mutaiton: Deletion is the loss of a segment of DNA from a chromosome, which can result in the loss of genetic information and potential loss of function.

duplication in block mutations?plication involves the copying of a segment of DNA, resulting in multiple copies of a particular gene or genes, which can lead to overexpression.

inversion in block mutations?

nversion occurs when a segment of DNA is reversed within a chromosome, which can affect gene expression and function.

What is translocation in block mutations:
Translocation is the movement of a segment of DNA from one chromosome to another non-homologous chromosome, which can disrupt gene function and regulation.

Question 23

What does it mean when a phenotype has a higher fitness value and is “at a selective advantage”?

Answer 23

A phenotype with a higher fitness value contributes more to the gene pool in the next generation, meaning it is more likely to survive and reproduce. This selective advantage allows favorable genes to be passed on to future generations.

Question 24

What happens to a phenotype with a lower fitness value in terms of natural selection?

Answer 24

A phenotype with a lower fitness value makes a lesser contribution to the gene pool in the next generation and is said to be “selected against,” meaning it is less likely to survive and reproduce, leading to a decrease in its frequency over time.

Question 25

The four conditions of Natural Selection

Answer 25

There is variation (physical, biochemical, behavioural) in phenotypes be speciifc variation in phenotype of the giraffes height eg.

A selection pressure exists that causes a struggle for survival in some individuals.
Organisms with a favourable phenotype will be selected for and have a selective advantage that helps them overcome the selection pressure.

The unfavoured phenotype is selected against and their numbers are reduced in the gene pool.

Those with the favourable phenotype pass their alleles to their offspring and inherit these traits. The frequency of the favourable allele increases.

Question 27

Natural Selection in peppered moths

Answer 27

1.There is variation in phenotypes within a population Light and dark coloured moths

2.A selection pressure exists (predation from birds) that causes a struggle for survival in some individuals.

3.Organisms with a favourable phenotype (dark moths in dark environments) will be selected for and have an advantageous phonotype that helps them overcome the selection pressure.

4,The unfavoured phenotype (light coloured moths in dark environment) is selected against and their numbers are reduced in the gene pool.

5,Those with the favourable phenotype pass their alleles to their offspring. The frequency of the favourable allele increases.

Question 28

Natural selection in mice

Answer 28

1, variation exists in popualation due to variation within the phenotypes of the differnet colours of mice

2,the fox acts as a selection pressure

selective advatnage is conferred upon the grey mice
4.the grey mice will have an increased chance of surviving and reproducing, allowing them to pass on their advantageious alleles ot the next generation

Question 29

Genetic drift what is and provide example and typesof genetic drift

Answer 29

involves changes to a population’s allele frequencies due to sudden and random occurrences

Examples include natural disasters or random movement to colonise a new population.

Two types:
Bottleneck effect
Founder effect

Question 30

Examples of selection pressures that act on a population

Answer 30

compeitition, predation, disease and climate chnage

Question 31

example of genetic drift

Answer 31

Examples include natural disasters or random movement to colonise a new population.

Question 32

What is the bottle neck effect

Answer 32

When a large portion of a population is wiped out due to a random event such as natural disaster

Only a small number of individuals remain in the gene pool and does not represent the original population

Loss of genetic diversity

Increase change of inbreeding

Question 33

What is the founder effect

Answer 33

Occurs when a small number of individuals colonise a new region and start a new population

This new population is known as colonising or founder population

The founding population has a small gene pool and low genetic diversity
Does not represent original population

The colonising population is exposed to different selection pressures as the original population

Mutations may arise forming new alleles

Question 34

How does genetic drift increase the risk of inbreeding, and what are the consequences?

Answer 34

Genetic drift can increase the chance of inbreeding by reducing genetic diversity, which limits the available gene pool. This can result in harmful alleles remaining in the population, leading to negative effects such as lower reproductive success and higher susceptibility to diseases.

Question 35

What is the effect of genetic drift on genetic diversity?

Answer 35

Genetic drift reduces genetic diversity, leading to an increased chance of inbreeding, which can keep harmful alleles in the gene pool. This results in a lower adaptive potential, making the population more vulnerable to new selection pressures.

Question 36

What is the difference between immigration and emigration in terms of allele exchange?

Answer 36

Immigration refers to individuals moving into a population, bringing new alleles that can increase genetic diversity. Emigration refers to individuals leaving a population, which can result in the loss of alleles from that population.

Question 37

How can the exchange of alleles through movement affect a population?

Answer 37

The exchange of alleles through movement (immigration and emigration) can increase genetic diversity by introducing new variants into a population or decrease diversity by removing alleles when individuals leave.

Question 38

Mechanisms of genetic drift and the consequences

Answer 38

1. bottle neck effect which reduces genetic diversity through the removal of alleles due to random events eg. natural disaster

2.founder effect which reduces genetic diversity through the establishment of a new population with a small unreperesentative sample of the original populaiton.

Question 39

Speciation

Answer 39

is the process by which populations genetically diverge until they become different species

Question 40

Species:

Answer 40

group of organisms that can interbreed to produce viable and fertile offspring

Can also be determined by DNA and amino acid sequences

Horse + donkey = mule. Therefore, not the same species

Question 41

Mechanisms which prevent species from interbreeding to produce fertile and viable offspring.

Answer 41

Geographical – physical barrier such as oceans and mountains
Ecological – different niches
Temporal – different breeding cycles
Behavioural – courtship behaviour
Structural – differences in reproductive organs

Question 42

Allopatric Speciation

Answer 42

Allopatric speciation occurs when a geographic barrier (such as an ocean or mountain) separates a population, isolating the two groups and preventing them from breeding. This lack of gene flow leads to genetic divergence, eventually resulting in the creation of a new species.

Question 43

What role does a geographic barrier play in allopatric speciation?

Answer 43

A geographic barrier physically separates a population into two or more isolated groups, preventing gene flow between them. Over time, this isolation leads to genetic divergence and the formation of new species.

Question 44

What happens if the two populations that underwent allopatric speciation meet again after being separated by a geographic barrier?

Answer 44

If significant genetic divergence has occurred during the separation, they may not be able to produce fertile and viable offspring, indicating they have become distinct species. If they can still interbreed and produce fertile offspring, they may not have diverged enough to be considered separate species.

Question 45

Process of allopatric speciation

Answer 45

a geographical barrier separates a population and no gene flow occurs.
Step 2; Different selection pressures act upon each population, favouring different phenotypes

step 3: Eventually, so much genetic variation has accumulated that the two populations can no longer interbreed even if the geographic barrier is removed.

Question 46

galapagos finches how did they form from allopatric speciation

Answer 46

The Galapagos Islands, consisting of 19 islands, each represent a specific ecological niche with different selection pressures. The islands are separated by ocean (a geographical barrier), preventing gene flow between populations. This has led to the evolution of 18 different species of Galapagos finches, each with unique beak shapes and sizes adapted to their environment and food source.

Question 47

Types of Galapagos finches and describe

Answer 47

Cactus finch has a thin and elongated break shape, their food soruce is mostly frm cacti as their thin elongated beak allows them to easily pick cactus seeds from the cacti without coming into contact with the spikes

Large ground finch- have thick and short beaks, their priary soruce of food is hard woody nuts and thier thick and short beaks allow them to forcfuelly break open and extract the interior ofthe woody nuts

Medium ground finch-
they have beakers with moderate width and short-their pirmary srouce of food is soft seeds because their moderate and short beaks allow them to only eat soft seeds due to the inabilty to break open harder seeds

Question 48

How do different species of Galápagos finches form through allopatric speciation?

Answer 48

: Different species of Galápagos finches form because, with no gene flow between isolated island populations, each island contains different selection pressures selecting for different phenotype This leads to genetic differences accumulating and the development of new species.

Question 49

Sympatric speciation

Answer 49

ormation of a new species in populations located in the same geographical location.

Question 50

Question: How can polyploidy lead to sympatric speciation?

Answer 50

Polyploidy, which occurs when an organism has additional sets of chromosomes, can lead to sympatric speciation. This genetic change, seen primarily in plants, can result in reproductive isolation within the same geographical location, allowing new species to form.

Question 51

where does polyploidy occur

Answer 51

Polyploidy occurs when an organisms contains additional sets of chromosomes in its genome.

Question 52

How is the speciation of Howea palms on Lord Howe Island an example of sympatric speciation?

Answer 52

Answer: The speciation of Howea palms on Lord Howe Island is an example of sympatric speciation because different pH levels in the soil led to the divergence of palm species within the same geographical area.

Question 53

How did speciation occur in Howea palms on Lord Howe Island?

Answer 53

Speciation in Howea palms on Lord Howe Island likely happened through sympatric speciation, meaning it occurred without physical separation.

Howea belmoreana lives in neutral and acidic soils, while Howea forsteriana adapted to alkaline soils. This difference in soil types acted as a selection pressure, pushing the populations to adapt differently.

As the population living in alkaline soils adapted, they developed traits like different flowering times, which led to reproductive isolation. This means the two groups could no longer interbreed effectively.

Over time, these differences became significant enough to result in the formation of two distinct species. The fact that this occurred without geographical isolation on the small island supports the idea that it was sympatric speciatio

Question 54

Selective breeding

Answer 54

Process by which humans can select or remove particular traits from a population by directly controlling the breeding of animals or plants

Question 55

Q: What are two benefits and disvantages of artificial selection?

Answer 55

1. Improved agricultural crops
2. Domestication of animals

disadvantges is that it can cause mutations and its inhumane.

Question 56

Process of Selective breeding

Answer 56

Determine the desired trait

Interbreed parents who show the desired trait

Select the offspring with the best form or desired trait and interbreed these organisms

Continue process until population reproduces desired trait

Question 57

Selective breeding in shepe

Answer 57

variation-sheep population has phenotypic variation. ranging from low to high wool density
2.Selection pressure- as high wool density is favourbale to humans, this trait is selected. Humans act as an artifical selection pressure and estbaolish a breeding population of sheep with high wool density, while indiividulas with low wool density are not permitted to breed.

3.Heritabilty-
As wool density is a heritable trait, the allele frequency of high wool density increases overtimeas only high wool density sheep are allowed to breed, Repeated selection reinforces high wool density expression

Question 58

The effect of selective breeding on genetic diversity

Answer 58

Loss of genetic diversity
Increased inbreeding
which can increase the prevalence of deleterious alleles

Lower adaptive potential – if new selection pressure arises, species may not survive

Question 59

What has led to the emergence of antibiotic-resistant bacteria?

Answer 59

Inappropriate use and overuse of antibiotics.

Question 60

Explain the variabilty, selection pressure, selective advantage and herbailty of bacteria

Answer 60

a
variation- a populaiton of bacteira has individuasl resistant to an antibioticas well as indiviudals susceptible to antibitoics
2.selection pressures- exposure to an antibiotic serves as an enviornmentla sleection pressure

3.selective advnatgae- a selective advantageis conferred to bactiera with resistance to antibitoics

4.Heritabilty- bacteria resistant to antibiotics are able to continue replicating nad and pass on the allele for resistance to other bactiera via bacteiral conjugation, increasing its allele frequecny

Bacterial conjugation is a process where one bacterium transfers genetic material to another through direct contact

Question 61

What are antibiotics and how do they work?

Answer 61

Antibiotics are chemicals that inhibit the growth of bacteria by interfering with their ability to build cell walls.

Question 62

Mechanisms of antibiotic resistance

Answer 62

inactivation- addition of a phosphate group to the antibiotic, reducing its ability to bind to bacterial ribosomes.

pumping out-increasing active efflux of the drug, expelling the antibitoic from bacterialcell

modification- changing the shape of a protein targetted by antibiotic, preventing the drug from binding effectively

4.impermabilty- Impermeability involves a modified cell wall protein that prevents the antibiotic from entering the bacterial cell.

Question 63

Factors which contribute to formation of antibiotic-resistant bacteria

Answer 63

Inappropriate compliance with treatment plan: course of antibiotics is prematurely stopped. May not eliminate all bacteria, which allows them to continue to replicate and time to accumulate mutations

Inappropriate use of antibiotics: antibiotics prescribed when they are not required. Normal flora is disrupted

Widespread use of antibiotics: increased use of antibiotics can increase the probability of antibiotic-resistant bacteria.

Question 64

How do viruses adapt and modify their surface antigens?

Answer 64

Viruses constantly adapt and modify their surface antigens through antigenic drift and antigenic shift, which allows them to increase virulence.

Question 65

Antigenic drift:

Answer 65

involves small and gradual changes to the genes encoding for viral surface antigens. As mutations accumulate, a new subtype of virus can form.

Question 66

Antigenic shift:

Answer 66

involves sudden and significant changes in the genes encoding for viral surface antigens. Occurs when two or more different strains combine when co-infecting a host resulting in viral recombination.

Question 67

How can antigenic drift and shift have thepotiental to delveop in an epidemic or pandemic?

Answer 67

: Antigenic drift and shift can lead to the emergence of new viral strains with the potential to develop into an epidemic or pandemic due to the virus’s increased ability to evade the immune system.

Question 68

What are the two surface antigens that researchers have identified for targeting in viruses? and

How can changes in haemagglutinin and neuraminidase affect vaccination and medication effectiveness?

Answer 68

The two surface antigens are haemagglutinin and neuraminidase.

haemagglutinin a glycoprotein responsible for bidning viruses ot the host cell facilcaiting their entranc inot the cell

Changes in haemagglutinin and neuraminidase can reduce or render obsolete the effectiveness of previous vaccinations and existing medications.

Question 69

What happens when chanegs occur in self antigens such as haemgluttin or neuraminidse

Answer 69

When changes occur in either of these surface antigens, the effectiveness of previous vaccinations and existing medications may be reduced, or rendered obsolete.