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AQA A Level Biology > 4-9/10 Genetics + Biodiversity > Flashcards

4-9/10 Genetics + Biodiversity Flashcards

1
Q

What is base substitution mutation?

A

when a nucleotide in the DNA sequence is replaced by another, a quick mutation

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2
Q

What is base deletion mutation?

A

a nucleotide is lost, more harmful, causes frameshift

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3
Q

What is a mutagenic agent?

A

factors increase the rate of gene mutation: x-rays, UV light

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4
Q

What are chromosome mutations?

A

when an individual has 3 or more sets of chromosomes instead of two

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5
Q

What is meiosis?

A

a form of cell division that produces four genetically different haploid cells

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6
Q

What happens during meiosis 1?

A

homologous chromosomes pair to form bivalents
crossing over occurs at chiasmata
the cell divides in two, separate randomly
each cell contains either a maternal or paternal copy

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7
Q

What happens during meiosis 2?

A

independent segregation of sister chromatids, the cell divides again to create 4 haploid cells

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8
Q

How does meiosis create a genetic variation?

A

crossing over, the independent assortment of chromosomes, resulting in new alleles

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9
Q

What is the importance of meiosis?

A

if gametes are haploid, chromosome number would double indefinitely

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10
Q

What is genetic combination?

A

exchange of genetic material between organisms resulting in reshuffling

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11
Q

What is genetic diversity?

A

the total number of different alleles in a population

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12
Q

What is the advantage of a high genetic diversity?

A

the ability to adapt to change in the environment allows natural selection

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13
Q

How does natural selection affect evolution?

A

random mutations result in new alleles, some more advantageous so they will survive and reproduce

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14
Q

What is directional selection?

A

when environmental conditions change, individuals with phenotypes suited to new conditions will survive to pass on genes, over time population will move towards those characteristics

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15
Q

What is stabilising selection?

A

when environmental conditions stay the same, individuals closest to the mean are favoured, any new characteristics are selected aginst

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16
Q

What are the three types of adaptation?

A

behavioural, physiological, anatomical

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17
Q

What is a species?

A

a group of organisms that can interbreed to produce fertile offspring

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18
Q

What is courtship behaviour?

A

identifying sexually mature members of their own species of the opposite sex, synchronise mating, form a pair bond and breed

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19
Q

How do you name species?

A

the binomial system

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20
Q

What are the principles of classification?

A

artificial
- observable characteristics
phylogenic
- evolutionary relationships + characteristics

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21
Q

How do you organise groups of species?

A 
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
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22
Q

What is phylogeny?

A

arranging organisms into groups based on evolutionary relationships and origins

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23
Q

What is biodiversity?

A

the variety of living organisms measured in species diversity ecosystem and genetic diversity

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24
Q

What is the species diversity index?

A

D = Σ(n / N)2

∑ = n(n-1)
N(N-1)

n = the total number of organisms of a particular species
N = the total number of organisms of all species
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25
Q

What is the impact of agriculture?

A

decreases species richness, pesticides, loss of habitat

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26
Q

How is the balance between conservation and farming maintained?

A

hedges > fences, rotate crops, limit pesticides

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27
Q

How do you compare DNA base sequences?

A

using gene technology + computers to read sequences, species have similar DNA

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28
Q

How do you compare mRNA sequences?

A

mRNA is reliant on DNA, the two will show the same results

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29
Q

How do you compare by amino acid sequence?

A

the amino acid sequence is determined by mRNA, which comes from DNA

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30
Q

How do you carry out random sampling?

A

randomly generated coordinates for a quadrant until sufficient data collected

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31
Q

How do you calculate standard deviation?

A 
√∑ (x-x_)2
       n-1
x = measured value
x_ = mean value
n = total values in samples
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32
Q

What is the process of prophase 1?

A

Chromosomes condense and become visible
Nuclear envelope breaks down

Contains 4n genetic material

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33
Q

What is the process of metaphase 1?

A

Homologous pairs of chromosomes line up next to each other
Spindle fibres connect to the centrioles

Contains 4n genetic material

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34
Q

What is the process of anaphase 1?

A

Homologous pairs are pulled apart to opposite poles of the cell
Contains 4n genetic material

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35
Q

What is the process of telophase 1?

A

Nuclei reform
Cytokinesis

Forms two cells with 2n genetic material each

36
Q

What is the process of prophase 2?

A

Nuclei break down

Contains 2n genetic material

37
Q

What is the process of metaphase 2?

A

Chromosomes lime up on the equator of the cell
Spindle fibres attach to the centromeres

Contains 2n genetic material

38
Q

What is the process of anaphase 2?

A

Chromatids are separated by the contraction of the spindle fibres
They’re pulled apart to opposite poles

Contains 2n genetic material

39
Q

What is the process of telophase 2?

A

Nuclei reform
Cell divides

Produces n genetic material per cell

40
Q

What are the two forms of variation during meiosis?

A

Independent segregation

Crossing over

41
Q

What is the process of independent segregation?

A

The homologous chromosomes randomly line up in meiosis 1 along the equator so the chromosomes at the poles are randomly selected

42
Q

What is the process of crossing over?

A

During meiosis 1, the chromatids become twisted round each other
The twisting creates tension where portions are broken off

43
Q

What is the aim of meiosis?

A

To create gametes (haploid cells) with half the number of normal chromosomes
To create sperm and ovum

To introduce variation

44
Q

What is a substitution reaction?

A

A nucleotide in a DNA molecule is replaced by another nucleotide that has a different base
This changes the amino acid and disrupts the primary structure

This could mess up the whole chain because the R groups affect the secondary and tertiary structure
A mutation could give you exactly the same amino acid and have little or no effect
It can change an enzyme’s active site so that it doesn’t work

45
Q

What is a deletion mutation?

A

DNA bases shift to the left which completely changes the sequence, stops the polypeptide from functioning

46
Q

What is meant by random fertilisation?

A

Any egg can be fertilised by any sperm which increases variation

47
Q

What is crossing over?

A

When portions of DNA are swapped between non-sister chromatids

48
Q

What is the role of the centromere during mitosis?

A

Centromere attaches to the spindle fibres

It allows separation in anaphase as centromere splits

49
Q

What are the steps of variation on a larger scale?

A

There is an initial gene pool
A random mutation occurs- mostly harmful

If it is advantageous, the organism is better adapted and more likely to live and breed
The offspring is also likely to have a new allele
Over time the allele frequency increases

50
Q

How do the conditions an organism lives in affect a mutation?

A

Happens no matter what conditions it lives in

The benefits of a mutation are determined by the environment

51
Q

What is a species?

A

A group of organisms that can interbreed to produce fertile offspring

52
Q

What is a population?

A

A group of organisms of the same species living in the same area

53
Q

What is directional selection?

A

When the normal distribution shifts to the left or right due to an environmental charge (selection pressure) or an advantageous mutation occurs
Graph shifts in favour of the advantageous allele

54
Q

What is stabilising selection?

A

Environmental conditions are stable
Individuals with phenotypes closest to the mean are favoured

These individuals are more likely to breed
It tends to eliminate phenotypes at the extremes
Graph: peak is higher and spread is narrower

55
Q

How does a mutation affect a protein receptor?

A

Change in DNA nucleotide sequence
Change in amino acid sequence

Alters position of hydrogen/ionic/disulfide bonds
Change in tertiary structure of receptor

56
Q

What is taxonomy?

A

The practise of grouping organism

57
Q

What is the binomial system?

A

Two names per organism

Only works for physical characteristics

58
Q

What are the subgroups of the binomial system?

A

Kingdoms - five levels
Phylum

Class
Order
Family
Genus
Species
59
Q

How are animals named?

A

Genus species
E.g. Homo* sapien, H.* sapien*, (Homo sapien)

  • = italics, () = underlined
60
Q

What are the three types of traits in animals?

A

Anatomical: where the different components are
Physiological: how an organism works

Behavioural: how the organism reacts to its environment and other organisms

61
Q

What is a species?

A

Organisms that can interbreed together and produce fertile offspring

62
Q

What is a phylogenetic group?

A

A group linked by evolution/genetic relationships/common ancestry

63
Q

How can information on amino acid sequences help to construct a phylogenetic tree?

A

Those with similar groups are closely related

The larger the differences between sequences, the longer ago the groups diverged

64
Q

What are the stages of courtship?

A

Recognition: recognising a member of the same species, scent can aid this
Capability: is the organism capable of mating, sometimes communicated

Forming a bond: being in close proximity, fighting over territory or offspring, protective bond
Synchronisation: takes place when there is a maximum probability of the sperm and egg meeting, oestrus is the time in which they are fertile and can conceive
Breeding

65
Q

How are phylogenetic relationships of different species represented?

A

Shows genetic links, not observable traits
All taxons have evolved from a common ancestor

Branch node represents a speciation event (can be an event which doen not remove the common ancestor)
Sister taxa are taxa which come from the most recent branch node, this means they are more genetically similar
X axis represents time
Variation can occur within a taxon

66
Q

What do farmers do that reduces the genetic variety of alleles?

A

They select species for particular qualities that make them more productive
Most of a farmers area is taken up by desirable species which means that other species have to compete for remaining resources which will reduce their numbers or cause them to go extinct

67
Q

Why do pesticides reduce the diversity index?

A

They exclude those species that compete with the farmed species for food, light, mineral ions and water
This reduces the diversity index

68
Q

What practises reduce biodiversity?

A

Removal of hedgerows and woodland
Creating monocultures e.g replacing a field with one crop

Filling in ponds and draining marsh/wetland
Over-grazing of land e.g upland areas by sheep which prevents regeneration
Use of pesticides and inorganic fertilisers

69
Q

What are the main conservation techniques?

A

Use hedges over fences as field boundaries
Maintain existing ponds and create new ones

Plant native trees on land with a low species diversity
Reduce pesticide use
Use organic fertilisers
Introduce conservation headlands- free of pesticides to aid wildlife

70
Q

How has the government encouraged conservation efforts?

A

Conservation methods make food more expensive so financial incentives have been put in place

71
Q

How do you calculate the means of grouped or tallied data?

A

Number of data values
f = frequency, x = data value
When x is a range, use the midpoint

72
Q

What is the individual?

A

One member of the population

73
Q

What is a population?

A

Members of the same species living in the same area

74
Q

What is a community?

A

Populations that live together in a defined area

75
Q

What is an ecosystem?

A

A community plus it’s non-living surroundings

76
Q

What is a biosphere?

A

All of the ecosystems on Earth

77
Q

What is a habitat?

A

The place where an organism lives

78
Q

What is the equation for the diversity index?

A

Sum of n(n - 1)
N = total number of all organisms
n = total number of each different species

79
Q

What are the limiting factors in aquatic environments?

A

Salinity
Dissolved oxygen content

Light
Temperature

80
Q

How can genetic diversity be compared?

A

The frequency of measurable or observable characteristics
The base sequence of DNA

The base sequence of mRNA
The amino acid sequence of the proteins encoded by DNA and mRNA

81
Q

In which types of sampling are quadrats and transects used?

A

Random- quadrat

Systematic- quadrat and transect

82
Q

What is the difference between species richness and diversity index?

A

The species index is the number of different species

The diversity index looks at the species richness as well as the abundance of each

83
Q

What is an abiotic factor?

A

A non-living factor

84
Q

What is a transect?

A

Sampling at regular intervals

Needs an abiotic factor to study e.g light intensty

85
Q

What is the general population curve?

A

Exponential curve then levels off once it reaches the carrying capacity

AQA A Level Biology (19 decks)

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