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Biology > GENETIC DIVERSITY - meoisiis + adaption > Flashcards

GENETIC DIVERSITY - meoisiis + adaption Flashcards

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1
Q

gene mutation

A

change in the sequence of base pairs in a DNA molecule that may result in an altered polypeptide
occur continuously
sometimes lead to a change in the polypeptide that the gene codes for

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2
Q

genetic code being degenerate

A

Most mutations do not alter the polypeptide or only alter it slightly so that its structure or function is not changed

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3
Q

different ways that a mutation in the DNA base sequence can occur:

A

Deletion of nucleotides
Substitution of nucleotides

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4
Q

deletion of nucleotides

A

when a nucleotide s randomly deleted from the DNA sequence
changes the amino acid that would have been coded for
changing the groups of three bases further on in the DNA sequence
may dramatically change the amino acid sequence produced therefore the ability of the polypeptide to function

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5
Q

types of Substitution of nucleotides

A

Silent mutations
Missense mutation
Nonsense mutations

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6
Q

what is subtstitution

A

a base in the DNA sequence is randomly swapped for a different base
only change the amino acid for the triplet
not have a knock-on effect

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7
Q

silent mutations

A

does not alter the amino acid sequence of the polypeptide (this is because certain codons may code for the same amino acid as the genetic code is degenerate)

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8
Q

Missense mutations

A

mutation alters a single amino acid in the polypeptide chain (sickle cell anaemia is an example of a disease caused by a single substitution mutation changing a single amino acid in the sequence)

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9
Q

Nonsense mutations

A

the mutation creates a premature stop codon (signal for the cell to stop translation of the mRNA molecule into an amino acid sequence), causing the polypeptide chain produced to be incomplete and therefore affecting the final protein structure and function (cystic fibrosis is an example of a disease caused by a nonsense mutation, although this is not always the only cause)

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10
Q

effect of gene mutations on polypeptides

A

Most mutations do not alter the polypeptide or only alter it slightly so that its appearance or function is not changed
However, a small number of mutations code for a significantly altered polypeptide with a different shape
This may affect the ability of the protein to perform its function.

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11
Q

affecting the ability of the protein to perform its function. For example:

A

If the shape of the active site on an enzyme changes, the substrate may no longer be able to bind to the active site
A structural protein (like collagen) may lose its strength if its shape changes

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12
Q

mutagnic agent

A

environmental factors that increase the mutation rate of cells
Examples include:
High-energy radiation such as UV light
Ionising radiation such as X rays
Toxic chemicals such as peroxides

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13
Q

Non-disjunction

A

occurs when chromosomes fail to separate during meiosis
This occurs spontaneously
gametes may end up with one extra copy of a particular chromosome or no copies of a particular chromosome
If the abnormal gametes take part in fertilization, then a chromosome mutation occurs as the diploid cell will have the incorrect number of chromosomes
Chromosome mutations involve a change in the number of chromosomes

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14
Q

Meiosis produces daughter cells that are genetically different from each other and to the parent cell
This is due to the processes of

A

crossing over
Independent assortment

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15
Q

independent assortmant

A

production of different combinations of alleles in daughter cells due to the random alignment of homologous pairs along the equator of the spindle during metaphase
different combinations of chromosomes in daughter cells increases genetic variation between gametes
ach pair can be arranged with either chromosome on top, this is completely random
The orientation of one homologous pair is independent / unaffected by the orientation of any other pair

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16
Q

crossing over

A

The process whereby a chromatid breaks during meiosis and rejoins to the chromatid of its homologous chromosome so that its alleles are exchanged

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17
Q

process of crossing ovrt

A

During meiosis I homologous chromosomes pair up and are in very close proximity to each other
The non-sister chromatids can cross over and get entangled
These crossing points are called chiasmata
The entanglement places stress on the DNA molecules
As a result of this a section of chromatid from one chromosome may break and rejoin with the chromatid from the other chromosome
can result in a new combination of alleles on the two chromosomes

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18
Q

The different combinations of chromosomes following meiosis

A

The number of possible chromosomal combinations resulting from meiosis is equal to 2n
n is the number of homologous chromosome pairs

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19
Q

The different combinations of chromosomes following fertilisation

A

In random fertilisation, any two gametes may combine
Therefore the formula to calculate the number of combinations of chromosomes after the random fertilisation of two gametes is (2n)2
n is the haploid number and 2 is the number of gametes
This explains why relatives can differ so much from each other. Even with the same parents, individuals can be genetically distinct due to variation at the meiosis and fertilisation stage (as well as other possible mutations and crossing-over)

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20
Q

DIFFERENCES OF THE PROCESSES OF MITOSIS AND MESOISIS

A

Mitosis contributes to the growth of an organism or to replace dead/dying cells
Meiosis produces genetically different gametes for sexual reproduction

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21
Q

The Different Outcomes of Mitosis and Meiosis

A

Number of daughter cells
Mitosis = 2
Meiosis = 4
Mitosis = 2n
Meiosis = n

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22
Q

what mitosis ends u wirh

A

two daughter cells genetically identical to each other and the parent cell
This is important so that growth and cell replacement can occur within a body continually
Every cell in an organism’s body (other than gametes) contain exactly the same genetic material

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23
Q

what mesoiss eds up with

A

four daughter cells all of which contain half the genetic material of the parent cell and are all different from each other and the parent
This is important for genetic variation within families and the population
Genetic variation can reduce the risk of inheriting genetic diseases

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24
Q

genetic variation

A

The small differences in DNA base sequences between individual organisms within a species population

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25
Q

what results in genetic diversity

A

Genetic variation is transferred from one generation to the next and it results in genetic diversity within a species population
is the number of different alleles of genes in a population

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26
Q

what does mutation reuslt in

A

the generation of new alleles and contributes to genetic diversity or the size of the gene pool
new allele may be advantageous,disadvantageous or have no apparent effect on phenotype

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27
Q

new alleles

A

The new allele may be advantageous, disadvantageous or have no apparent effect on phenotype (due to the fact that the genetic code is degenerate
New alleles are not always seen in the individual that they first occur in
They can remain hidden (not expressed) within a population for several generations before they contribute to phenotypic variation

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28
Q

effect of genetic diversity

A

There needs to be some level of genetic diversity within a population for natural selection to occur

Differences in the alleles possessed by individuals within a population result in differences in phenotypes

Environmental factors affect the chance of survival of an organism; they, therefore, act as a selection pressure

increase the chance of individuals with a specific phenotype surviving and reproducing over others

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29
Q

f a population has a small gene pool

A

low genetic diversity then they are much less able to adapt to changes in the environment and so can become vulnerable to extinction

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30
Q

Principles of Natural Selection

A

Random mutation can produce new alleles of a gene
Many mutations are harmful or neutral but, under certain environmental conditions, the new alleles may benefit their possessor, leading to an increased chance of survival and increased reproductive success
The advantageous allele is passed onto the next generation
As a result, over several generations, the new allele will increase in frequency in the population

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31
Q

Example of Natural selection in Rabbits

A

Variation in fur colour exists within rabbit populations
At a single gene locus, normal brown fur is produced by a dominant allele whereas white fur is produced by a recessive allele in a homozygous individual
Rabbits have natural predators like foxes which act as a selection pressure
Rabbits with a white coat do not camouflage as well as rabbits with brown fur, meaning predators are more likely to see white rabbits when hunting
As a result, rabbits with white fur are less likely to survive than rabbits with brown fur
Therefore, the rabbits with brown fur have a selection advantage, so they are more likely to survive to reproductive age and be able to pass on their alleles to their offspring
Over many generations, the frequency of alleles for brown fur will increase and the frequency of alleles for white fur will decrease

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32
Q

Natural selection causes

A

a change in allele frequencies over time
Selection pressures (caused by the environment an organism is in) increase the likelihood that certain individuals with specific alleles survive to reproductive age, enabling them to pass on their alleles to their offspring

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33
Q

community

A

Multiple populations (of different species) living and interacting in the same area

34
Q

Ecosystems

A

Communities interact with the non-living components of the environment they live in, forming ecosystems

The interaction between a community (the living, biotic part) and the non-living (abiotic) parts of the environment

35
Q

Niche

A

The place where a species lives within an ecosystem is its habitat
The role that a species plays within its habitat is known as its niche
biotic interactions
abiotic interactions

36
Q

how many species can a niche be occupied by

A

only be occupied by one species, meaning that every individual species has its own unique niche

37
Q

what happens when two species occupy a niche

A

they will compete with each other for the same resources
One of the species will be more successful and out-compete the other species until only one species is left and the other is either forced to occupy a new, slightly different niche or to go extinct from the habitat or ecosystem altogether

38
Q

Adaptations to abiotic and biotic conditions

A

Adaptations are features of organisms that increase their changes of surviving and reproducing. These adaptations can be:
Anatomical (e.g. structural features such as horns, claws or feathers)
Behavioural (e.g. courtship of defensive behaviours)
Physiological (e.g. processes inside the body such as venom production or the ability to digest cellulose)

39
Q

The Effect of Abiotic Factors on Biodiversity

A

The changes that species produce in their abiotic environment can actually result in a less hostile environment
As a result, this can change or sometimes increase the biodiversity within that environment

40
Q

maximum stable population size

A

that an ecosystem can support is known as the carrying capacity

41
Q

Abiotic factors affecting population size

A

Abiotic factors involve the non-living parts of an ecosystem
Some examples of abiotic factors that can limit population size include:
light availability
water supply
temperature
amount of space available
soil pH

42
Q

if the temperature of their surroundings is significantly lower or higher than the optimum body temperature for that species

A

individuals will have to use up a significant amount of energy to maintain their optimum body temperature (via homeostasis)
As each individual now has less energy available for growth and reproduction, fewer individuals reach reproductive age and successfully reproduce, meaning that population growth is limited

43
Q

Biotic factors affecting population size

A

Biotic factors involve the living parts of an ecosystem
Biotic factors are the interactions between organisms
This includes things like competition for resources and predation

44
Q

Biotic factors can be split into three main types:

A

Interspecific competition
Intraspecific competition
Predation

45
Q

Interspecific competition

A

ompetition for the same resources between individuals from different species
competition between species means that the sizes of both populations are limited
competition between species can lead to a decrease in the population size of one of the species and an increase in the population size of the other

46
Q

Intraspecific competition

A

This is competition for the same resources between individuals from the same species

47
Q

Example of infra specific competition

A

When resources are plentiful, the population of grey squirrels increases
As the population increases, however, there are more individuals competing for these resources (e.g. food and shelter)
At some point, the resources become limiting and the population can no longer grow in size - the carrying capacity has been reached

48
Q

Predation

A

Producers are eaten by primary consumers, which in turn may be eaten by secondary consumers who are themselves eaten by tertiary consumers

Consumers that kill and eat other animals are known as predators

49
Q

Predator prey cycle

A

The number of predators increases as there is more prey available
The number of prey then decreases as there are now more predators
The number of predators decreases as there is now less prey available
The number of prey increases as there are now fewer predators
The cycle now repeats

50
Q

What is sampling

A

Sampling is a method of investigating the abundance and distribution of species and populations

51
Q

are two different types of sampling:

A

Random
Systematic

52
Q

In random sampling

A

the positions of the sampling points are completely random or due to chance
This method is beneficial because it means there will be no bias by the person that is carrying out the sampling that may affect the results

53
Q

Systematic sampling

A

the positions of the sampling points are chosen by the person carrying out the sampling
There is a possibility that the person choosing could show bias towards or against certain areas
Individuals may deliberately place the quadrats in areas with the least species as these will be easier and quicker to count
This is unrepresentative of the whole area

54
Q

Sampling methods

A

Quadrats

Transects

Mark-release-recaptur

55
Q

Frame quadrats

A

Quadrats must be laid randomly in the area to avoid sampling bias
This random sampling can be done by converting the sampling area into a grid format and labelling each square on the grid with a number
Then a random number generator is used to pick the sample points
Once the quadrat has been laid on the chosen sample point the abundance of all the different species present can be recorded

56
Q

Why use transects

A

can help show how the distribution or abundance of a species changes with the different physical conditions in the area
A transect is a line represented by a measuring tape, along which samples are taken

57
Q

For a belt transect

A

Place quadrats at regular intervals along the tape and record the abundance of each species within each quadrat
This produces quantitative data

58
Q

Mark release and capture

A

The first large sample is taken. As many individuals as possible are caught, counted and marked in a way that won’t affect their survival e.g. if studying a species of beetle, a small amount of brightly coloured non-toxic paint can be applied to their carapace (shell)
The marked individuals are returned to their habitat and allowed to randomly mix with the rest of the population
When a sufficient amount of time has passed another large sample is captured
The number of marked and unmarked individuals within the sample are counted
The proportion of marked to unmarked individuals is used to calculate an estimate of the population size

59
Q

Belt transects equation

A

N = (n1 × n2) ÷ m2

N = population estimate
n1 = number of marked individuals released
n2 = number of individuals in the second sample (marked and unmarked)
m2 = number of marked individuals in the second sample

60
Q

Assumptions from mar release capture

A

marked individuals are given sufficient time to disperse and mix back in fully with the main population
The marking doesn’t affect the survival rates of the marked individuals (e.g. doesn’t make them more visible and therefore more likely to be predated)
The marking remains visible throughout the sampling and doesn’t rub off
The population stays the same size during the study period (i.e. there are no significant changes in population size due to births, deaths or migrations into or out of the main population)

61
Q

Ecosystem

A

A relatively self-contained unit consisting of a community (or multiple communities) of species interacting with each other and with the non-living components of their environment

There are both living (biotic) and non-living (abiotic) components within an ecosystem

62
Q

succession

A

ecosystems change from being very simple to being relatively complex
Stages where new species colonise an area and change the environment
May make the encvironment less suitable for existing species and more suitable for others with different adaptions

63
Q

Primary succession

A

when newly formed or newly exposed land (with no species present) is gradually colonised (inhabited) by an increasing number of species

This new uninhabited land can be created in several ways.

64
Q

How new uninhabitable land can be created

A

The magma from erupting volcanoes cools and often leads to the formation of new rock surfaces or even new rocky islands in the sea
Another way new land can be exposed is by sea-level dropping or the drying up of a lake, leaving areas of bare rock

65
Q

Sand dunes primary succession

A

coastal areas (marram grasses are the pioneer species in these environments as they have deep roots to access water that other plants can’t reach and are able to tolerate the salty environment i.e. the high concentrations of sodium and calcium ions caused by sea spray)

66
Q

prey

A

Consumers that kill and eat other animals are known as predators, and those eaten are known as prey

67
Q

Primary Succession Occurs in a Series of Stages

A

Firstly, seeds and spores that are carried by the wind land on the exposed rock and begin to grow pioneer species die and decompose, the dead organic matter (humus) forms a basic soil

Seeds of small plants and grasses land on this basic soil and begin to grow

these small plants and shrubs die and decompose, the new soil becomes deeper and more nutrient-rich

Larger plants and shrubs, as well as small trees, that require deeper, more nutrient-rich soil, can now begin to grow
soil is sufficiently deep, contains enough nutrients and can hold enough water to support the growth of large trees
These final species to colonise the new land become the dominant species of the now relatively complex ecosystem
The final community formed, containing all the different plant and animal species that have now colonised the new land, is known as the climax community

68
Q

Examples of a Changing Environment During Succession

A

Pioneer species that first colonise and grow on the bare rock, such as lichens, help to slowly break apart the top surface of the rock. As pioneernspecies die and decompose humus builds up. In this way, the lichens gradually change the local environment so that it becomes more suitable for other species, such as mosses. This cast shades to stop further growth of lichens . Their roots are longer and so further break up the rock.
Organic matter increases as these bigger plants die more water retained so grasses shrubs and more flowering plants grownEventually, these species result in the formation of a thin soil layer that covers the newly formed rock surface completely. As lichens cannot grow on soil, they now disappear from the ecosystem.
Finally, as the soil deepens further and trees are able to grow, they may then out-compete certain shrubs and other smaller plant species, which may no longer be able to grow beneath the trees due to a lack of light
Eventually the area colonised by dominant plant species and a stable climax community is reached.

69
Q

what interrupts process of succession

A

Human activities
stops a climax community from developing

70
Q

what interrupts process of succession examples

A

If left alone, a grassy field would eventually develop into an area of shrubs and trees due to the process of succession. However, regular mowing prevents these larger, more woody plants from establishing themselves, so succession can’t occur (only the small grasses can survive being regularly mowed)
Similarly, in areas where livestock such as sheep, horses or cattle are kept, succession is halted by the grazing activity of these animals, which eat any new plant shoots trying to grow. Again, grasses are the main plant species that can remain established in these areas

71
Q

Managing Succession

A

the protection and management of ecosystems

72
Q

Preventing Succession

A

Grazing animals can be introduced temporarily.
Managed burning can be used, during which controlled fires are deliberately lit and allowed to burn away the shrubs and trees.

73
Q

burning fires

A

. Species such as heather (a key moorland plant) grow back quickly in their place. This resets the process of succession, meaning the larger, woody plants will take a long time to grow back, at which point the burning can be repeated

74
Q

Grazing animals

A

they eat the growing shoots of shrubs and trees, this stops these plants from establishing themselves and prevents succession

75
Q

Methods of Conservation

A

National parks- several restrictions
Humans access is strictly controlled
Industrial activities such as agriculture and building are tightly regulated
Hunting is limited or completely prohibited

Marine parks-also have restrictions to prevent overfishing and pollution

Public engagement-Some of the profits made from parks can be used to improve the health and education standards in the nearby communities to illustrate the benefits of having such areas nearby

76
Q

Conservation in Captivity

A

Zoos can also contribute towards the conservation of endangered animal species
Captive breeding programmes can breed individuals of a species so their offspring can be released into the wild

77
Q

problems with zoos

A

Captive breeding of small species populations can reduce genetic diversity
Certain animal species will not breed in captivity
Not all zoos can provide adequate habitats for animals with specific needs

78
Q

Botanic gardens

A

cuttings and seeds collected from the wild to establish a population of the endangered species in captivity

79
Q

Frozen zoos

A

Storing Genetic Material for Conservation
deally, samples are collected from different individuals of the same species to maintain the gene pool
The temperature used is roughly -196oC
A large amount of genetic material can be stored in a relatively small space
In the future genetic materials from extinct animal species could be used to breed and reintroduce a species through IVF and genetic engineering

80
Q

seed bank

A

conserves plant diversity by drying and storing seeds in a temperature-controlled environment
Usually, seeds of the same species are collected from different sites to maintain the gene pool
If the plant species goes extinct then the seeds can be used to grow them again
Seeds can only be stored for so long. After a certain period of time, the stored seeds are grown into plants and fresh seeds for storage are taken from those plants

81
Q

Secondary succession

A

Event that disrupts the community but soil structure remains in plants

82
Q

Typical colonisers

A

Large quantities of wind dispersed seeds
Rapid termination
Photosyytetic
Fix nitrogen
Tolerate extreme conditions

Biology (58 decks)

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