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Question 1

what is a gene pool

Answer 1

the complete set of alleles present within a particular population

Question 2

what is allele frequency

Answer 2

the proportion of certain alleles in a gene pool

Question 3

what are environmental selection pressures

Answer 3

factor in the environment (e.g. limited resources, deforestation, changing temperature, predation) that impacts an organism’s ability to survive and reproduce

Question 4

what is natural selection

Answer 4

a mechanism through which organisms that are better adapted to their environment have an increased chance of surviving and passing on their alleles

Question 5

natural selection answer

Answer 5

Variation in [insert phenotype] exists in the population that is heritable, with some being [insert phenotype 1] and others being [insert phenotype 2]

There is [describe the selection pressure] which means that those with [insert the favourable phenotype] are more likely to survive whilst those with [insert the unfavourable phenotype] are more likely to die (or unable to reproduce depending on the scenario. Not everyone dies all the time)

The individuals with [insert favourable phenotype] are more likely to reproduce and pass on the alleles for the favourable trait to the next generation. Over time the incidence of the allele for [insert trait] will increase in the gene pool.

Question 6

how does allele frequency change with environmental pressures

Answer 6

As advantageous traits become more common in a population, the allele frequencies of the population changes, with the frequency of the advantageous allele increasing.
Eventually, the evolution of the species can occur.

Question 7

what is genetic drift

Answer 7

Random changes in the gene frequencies of a population from generation to generation

Question 8

types of genetic drift

Answer 8

founder effect - the reduction in genetic diversity that occurs when a population is derived from a small unrepresentative sample of the original population

bottleneck effect - the reduction in genetic diversity that occurs when a large proportion of a population is removed due to a chance event

Question 9

how does allele frequency change with genetic drift

Answer 9

the removal of the alleles decreases the genetic diversity of the population

Question 10

what is genetic flow

Answer 10

the flow of alleles in and out of a population due to the migration or interbreeding of individuals between two populations

Question 11

how does gene flow affect genetic diversity and allele frequencies

Answer 11

gene flow into the population (immigration) can increase genetic diversity, influencing smaller populations more than larger ones

gene flow out of the population (emigration) decreases genetic diversity

Question 12

what are mutations

Answer 12

a permanent change to a DNA sequence

Question 13

what are the different mutations + how do they affect alleles

Answer 13

point mutation- a mutation that alters a single nucleotide in a DNA sequence

block mutation- a mutation that affects a large chunk of DNA, or an entire gene

silent mutation- a mutation in which a nucleotide is substituted for another, changing the codon, but still coding for the same amino acid. Therefore, there is no effect on protein structure

missense mutation - a mutation in which a nucleotide is substituted for another, changing the codon and coding for a different amino acid. Therefore, there can potentially be an effect on protein structure

nonsense- mutation a mutation in which a nucleotide is substituted for another, changing the codon to a stop codon, prematurely ceasing translation of the gene’s mRNA. Therefore, there is an effect on protein structure

frameshift mutation- a mutation that involves the insertion or deletion of one or two nucleotides, altering every codon from that point forward

Question 14

how do mutations change allele frequencies

Question 15

selective breeding

Answer 15

the changing of a population’s gene pool due to humans altering the breeding behaviour of animals and plants to develop a selected trait.

Question 16

how does selective breeding affect populations

Answer 16

Additionally, reduced genetic diversity can lead to increased inbreeding, which can increase the prevalence of deleterious alleles, and a lower adaptive potential. These two effects are detrimental to the survival of a population.

Question 17

what is bacterial resistance

Answer 17

the ability of a microorganism to survive exposure to an antimicrobial agent

Question 18

how does bacteria become antibiotic resistant

Answer 18

being exposed to antibiotics can lead to antibiotic resistance, as bacteria with the mutation which allows them to survive

natural selection

Question 19

how do virus’ challenge current treatments

Question 20

different types of fossils

Answer 20

index fossils – similar fossils found in different locations
needs to be easily recognisable
widespread
short lived – in the stratum

transitional fossils – a fossil that shows traits that are common to both its ancestral group and its descendant group. They are particularly important when the descendant species is physically very distinct from the ancestral species, such that the transitional fossil can help demonstrate evolutionary changes between the two

Question 21

how are fossils formed

Answer 21

the organism dies
the body of the organism is rapidly buried by sediment in a low oxygen environment
hard tissue in the body is impregnated by minerals as soft tissues decomposes

Question 22

how can the fossil record be used as evidence of biological change

Answer 22

transitional fossils are ones that show an intermediate step between an ancestor group and a decendent group. This allows researchers to show evolutionary changes between the ancestor to the current times species.

Question 23

why are there gaps in the fossil record

Answer 23

• not everything has been found
• only hard tissue can fossilise
• ancient DNA degrades over time

Question 24

how des carbon 14 dating work

Question 25

what is a species

Answer 25

a group of individuals who are able to breed with each other and produce viable and fertile offspring

Question 26

how have two species speciated answer

Answer 26

Members of a population are separated by a barrier [describe it] that prevents gene flow

In their respective isolated areas, each population faces different selection pressures [include them if they’ve been mentioned] and over time their gene pools change in response to natural selection and genetic drift

The two populations will accumulate enough genetic differences that if they were to be reintroduced and interbred with each other, they would be unable to produce viable and fertile offspring

Question 27

what is allopatric speciation answer

Answer 27

A geographical barrier separates a population, preventing gene flow.

Different selection pressures act upon each population, favouring different phenotypes and allowing for genetic differences to accumulate.

Eventually, suffcient genetic differences accumulate so that the two populations can no longerinterbreed to produce viable and fertile offspring.

Question 28

what is sympatric speciation

Answer 28

Sympatric speciation involves the formation of a new species in populations located in the same geographical location

Question 29

similarities and differences b/w sympatric and allopatric

Answer 29

similarities:

differences:

Question 30

galapagos finches speciation

Answer 30

Each of the Galapagos islands have an ecological niche
as allopatric speciation occurred, the birds speciated to survive in each of the environments on each of the islands

Question 31

Howea palms speciation

Answer 31

Researchers have concluded that sympatric speciation was driven by the flowering times of the different palms, which was affected by the differing soil pH that they grew in. H. forsteriana prefers alkaline pH soils such as calcarenite, whilst H. belmorana prefers acidic or neutral pH soils such as volcanic soil

Question 32

homologus structures

Answer 32

features present in two or more species that may look and function very differently in each species, but are derived from a common ancestor

Question 33

vestigial structures

Answer 33

vestigial structures features that have lost all or most of their usefulness as a result of evolution by natural selection

Question 34

how is DNA used to determine relatedness (pros and cons)

Answer 34

DNA bases are compared to find the degree of relatedness between species

A limitation to analysing amino acid sequences is that closely related species are likely to share very similar sequences for certain proteins.
In these instances, scientists determine relatedness by comparing nucleotide sequences, looking for silent mutations that, due to the redundancy of the genetic code, may have accumulated without altering the amino acid sequence.

Amino acid sequences are easier to interpret and are therefore
used to determine relatedness in more distantly related species.

Besides DNA and amino acid sequences, we can also compare whole genomes of different
species. The higher the degree of similarity between the genomes of different species,
the more related they are and the more recent they diverged from a common ancestor.

Question 35

how is amino acid sequences used to determine relatedness (and pros and cons)