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biology ~ genetics, variation and interdependence > genetic diversity and adaptation > Flashcards

genetic diversity and adaptation Flashcards

1
Q

differences in organisms

A

-organisms of the same species have very similar genomes
-there will be differences between their DNA base sequence

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2
Q

size of differences between individuals of the same species

A

small differences

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3
Q

genetic variation

A

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

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4
Q

genetic variation transferred

A

genetic variation is transferred from one generation to the next

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5
Q

result of Genetic variation is transferred from one generation to the next

A

genetic diversity within a species population

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6
Q

genetic diversity

A

number of different alleles of genes in a population

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7
Q

mutation results in

A

genetic diversity if new alleles and contributes to genetic diversity or size of the gene pool

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8
Q

effect of mutation

A

-new allele may be advantageous, disadvantageous or have no apparent effect phenotype (due to genetic code being 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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9
Q

what is needed for natural selection to occur

A

some level of genetic diversity within a population

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10
Q

differences in alleles possessed by individuals within a population results in

A

difference in phenotypes

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11
Q

environmental factors affect the chance of individuals within a specific phenotype surviving and reproducing over others acts as a

A

selection pressure

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12
Q

individuals described as having a higher fitness have

A

favored phenotype

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13
Q

fitness of an organism

A

-defined as its ability to survive and pass on its alleles to offspring
-organisms with higher fitness posses adaptations that make them better suited to their environment

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14
Q

population with a large gene pool or high genetic diversity

A

has a string ability to adapt to change

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15
Q

population has a small gene pool or very low genetic diversity

A

much less able to adapt to changes in the environment and so become vulnerable to extinction

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16
Q

cheetahs as an example of having a small gene pool

A

-cheetahs are an example of a species with an extremely small gene pool
-they experienced a very large decline in numbers approximately 10,000 years ago
-this left small, fragmented populations of individuals remaining
-there was no mixing between population and large amounts of inbreeding occurred
-this is problematic for conservation as low genetic variation means the species are less likely to be able to respond (survive) in the event if any environmental changes

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17
Q

bacteria colonies growth

A

can grow at rapid rates when in culture with very large numbers of bacteria produced within long hours

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18
Q

why is dealing with experimental data relating to large numbers of bacteria difficult using traditional linear scales

A

-there is a wide range of very small and very large numbers
-this makes it hard to work out a suitable scale for the axes of graphs

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19
Q

useful scales when investigating bacteria

A

logarithmic scales

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20
Q

logarithmic scales allow for

A

a wide range if values to be displayed on a single graph

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21
Q

example of logarithmic graph using yeast cells

A

-yeast cells were grown in culture over several hours. the number of cells increased very rapidly form original number of yeast cells present
-can be shown on a log scale
-the number of yeast cells present at each time interval was converted to a logarithm before being plotted on the graph
-the log scale is easily identifiable as there are no equal intervals between numbers on the y-axis
-the wide range of cell numbers fit easily onto the same scale

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22
Q

why is pH scale logarithmic

A

concentration of hydrogen ions varies massively between each pH level

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23
Q

why does genetic variation exist within populations

A

presence of different alleles

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24
Q

where is there different reproductive success

A

between organisms with different alleles of the same gene

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25
Q

reproductive success

A

number of offspring an individual produces (per breeding event or in their lifetime)

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26
Q

when will individuals with certain alleles have an increased chance of survival and reproduction

A

under certain environmental conditions

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27
Q

how can new alleles arise on populations

A

random mutation

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28
Q

natural selection can cause

A

the frequency of alleles in a population to change overtime

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29
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 reproductive success
-this advantageous allele is passed onto the next generation
-as a result, over several generations, the new allele will increase in frequency in the population

30
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 selection pressure
-rabbits with a white coat do not camouflage as well as rabbits with brown fur, meaning predators are more likely to see rabbits with brown fur
-therefore, the rabbits with brown fir have a selection advantage, so they are more likely to survive to a 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 of white fur will decrease

31
Q

what does natural selection cause

A

a change in allele frequencies over time

32
Q

why does Natural selection causes a change in allele frequencies over time

A

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 alleles to their offspring

33
Q

natural selection

A

Darwin’s theory to explain the mechanism of evolution. the processes by which organisms better adapted to their environment survive and reproduce and pass on their advantageous alleles to their offspring, whilst those less well adapted fail to do so

34
Q

other factors or processes that can effect allele frequencies in a population

A

-founder effect
-genetic drift
-the bottleneck effect

35
Q

the founder effect

A

-occurs when only a small number of individuals from a large parent population start a new population
-as the new population is made of only a few individuals from the original population only some of the total alleles from the parent population will be present
-so not all the gene pool is present in the smaller population –> a gene pool is the complete range of DNA sequences (allele) that exist in all the individuals of a population or species
-which alleles end up in the new founding population is completely up to chance
-as a result, the changes in allele frequencies may occur in a different direction for the new small population vs the larger parent population

36
Q

the founder effect in lizards

A

-anole lizards inhibit mist Caribbean islands and they can travel from one island to another via floating debris or vegetation
-the individual lizards that arrive on the island, as well as they alleles they carry is due to chance
-they may only carry a small selection of alleles, with many more alleles present in the lizard population on the original island
-the lizards on the island could display a range of scale colours from white to yellow and the two individual lizards that arrived on the island might only have individuals with white scales
-this means hat the whole population that grows on that island might only have individuals with white scales
-In comparison, the original island population has a mixture of white and yellow scaled individuals. This difference between the two populations is completely due to chance

37
Q

genetic drift

A

-when a population is significantly small, chance can affect which alleles get passed onto the next generation
-over time some alleles can be lost of favoured purely by chance
-when there is a gradual change in allele frequency in a small population due to chance and not natural selection then genetic drift is occurring

38
Q

example of genetic drift in plants

A

-in a small population of 5 plants growing near a playground with rubber floor: 3 of the plants have pink and white flowers
-by chance, most of the seeds from the pink-and-white flowered plants end up on the rubber floor of the playground, whereas all the seeds from the blue-and-white flowered plants land on fresh fertile soil where they are able to germinate and grow
-Over several generations, the allele for the pink-and-white flowers may disappear from this population due to chance (because the seeds carrying pink-and-white alleles for flower colour cannot germinate on rubber)

39
Q

bottleneck effect

A

-similar to the founder effect
-it occurs when a previously large population suffers a dramatic fall in numbers
-a major environmental event can massively reduce the number of individuals in a population which in turn reduced the genetic diversity in the population as alleles are lost
-the supervising individuals end up breeding and reproducing with close relatives

40
Q

example of the bottleneck effect

A

A clear example of a genetic bottleneck can be seen in cheetahs today
Roughly 10,000 years ago there was a large and genetically diverse cheetah population
Most of the population was suddenly killed off when the climate changed drastically at the end of the Ice Age
As a result, the surviving cheetahs were isolated in small populations and lots of inbreeding occurred
This meant that the cheetah population today has a serious lack of genetic variation
This is problematic for conservation as genetic variation within a species increases the likelihood that the species is able to respond (survive) in the event of any environmental changes
Remember the environment exerts a selection pressure on organisms

41
Q

selection pressures

A

environmental factors that affect the chance of survival of an organism are selection pressures

42
Q

example of selection pressures

A

there could be high competition for food between lions if there is not plentiful prey available, this environmental factor selects faster, more powerful lions that are better hunters

43
Q

effects of selection pressures

A

the allele frequencies of a population through natural selection

44
Q

types of selection

A

-stabilising
-directional

45
Q

stabilising selection

A

natural selection that keeps allele frequencies relatively constant over generations

46
Q

what does stabilising selection means

A

things stay as they are unless there is a change in the environment

47
Q

example of stalibilsing selections in human birth rates

A

very-low and very-high birth weights are selected against leading to the maintenance of the intermediate birth weights

48
Q

directional selection

A

natural selection that produces a gradual change in allele frequency over several generations

49
Q

when does gradual selection usually occur

A

when there is a change in environment/selection pressures or a new allele has appeared in the population that is advantageous

50
Q

example of directional selection in antibiotic resistant bacteria strains are becoming more common due to overuse of antibiotics

A

-the presence if antibiotics is a selection pressure
-mutations are becoming in bacteria populations randomly
-a mutation arises that confers antibiotic resistance - it has a beneficial allele
-bacteria with this mutation are more likely to survive and reproduce
-most bacteria with this mutation are more likely to survive and reproduce
-most bacteria without the resistance mutation die
-over generations, this leads to an increase in the frequency of beneficial allele that produces antibiotic resistance

51
Q

affect of selection pressures on allele frequencies

A

have different effects on allele frequencies of a population through natural selection

52
Q

adaptations

A

certain alleles within a species population can produce features that make an organism better suited to its environment

53
Q

when is there potential for relatively rapid changes in a species

A

when new alleles of genes reult form mutations there is the potential for relatively rapid change in a species if their environement changes

54
Q

example of favourable allele in lion population

A

a higher proportion of fast-twitch muscle fibres in their legs, which is advantageous for sprinting after prey

55
Q

natural selection will select

A

favourable alleles that produce adaptations

56
Q

what will natural selection select against

A

unfavourable alleles

57
Q

over time natural selection will cause

A

favourable allele frequencies to increase and unfoavourable allele frequencies to decrease, making the sapecies better adapted for the environment

58
Q

3 types of adaptations

A

-anatomical adaptations
-physiological adaptations
-behavioral adaptations

59
Q

anatomical adaptations

A

-structural/physical feature
-for example the white fur of polar bears provides camouflage in the snow so it has less chance of being detected by prey

60
Q

physiological adaptations

A

-biological processes within the organisms
-for example mosquito’s produce chemicals that stop the animal’s blood clotting when they bite, so they can feed more easily

61
Q

behavioural adaptations

A

-the way an organism behaves
-for example cold-blooded reptiles bask in the sun to absorb heat

62
Q

2 major factors in the process of evolution

A

adaptation and selection

63
Q

evolution

A

change in adaptive features of a population over time as a result of natural selection

64
Q

evolution in a static environment

A

will not occur as selection pressures will not change

65
Q

effect of environmental changes or chance mutations on selection pressures

A

may favour individuals with different characteristics or with the new allele

66
Q

what processes does natural selection result in

A

adaptation. which means that over generations, those features that are better adapted to the environment became more common, this means whole populations of organisms become better suited to the environment

67
Q

what happens if two species are isolated from each other

A

they may become so different in phenotype that they can no longer interbreed to produce fertile offspring, they have formed 2 new species

68
Q

what is formation of new species from pre-existing species over time a result of

A

accumulated genetic differences

69
Q

what is evolution responsible for

A

large number of species that exist on earth as drives speciation

70
Q

practical of affecting microbial growth- important techniques used

A

aseptic techniques

71
Q

why are aseptic techniques used

A

ensure microbes being investigated don’t escape or become contaminated with another unwanted, and possibly pathogenic microbe

72
Q

examples of aseptic techniques

A

-disinfecting work surfaces with disinfectant/alcohol
-not allowing growth if microorganisms at body temperature
-using famed loops or sterile swabs when transferring cultures
-wearing gloves and googles
-flaming culture bottlenecks to prevent contamination
-having a lit Bunsen burner in the room
-only removing perti dish lids when necessary

biology ~ genetics, variation and interdependence (4 decks)

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