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Biology aqa AS > diversity, classification and variation > Flashcards

diversity, classification and variation Flashcards

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1
Q

how is DNA passed from one generation to the next

A

gametes

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2
Q

what are gametes

A

sperm cells in males, egg cells in females,that join together during fertilisation to form a zygote

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3
Q

what does a zygote do

A

divides and develops to from a new organism

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4
Q

what do normal body cells have

A

diploid number of chromosomes

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5
Q

what does diploid mean

A

contains 2 of each chromosome, one from mother and one from father

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6
Q

what do gametes contain

A

haploid number

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7
Q

what does haploid mean

A

only one copy of each chromosome

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8
Q

what happens during fertilisation

A

haploid sperm fuses with haploid egg to produce diploid cell

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9
Q

how does fertilisation create genetic variation

A

it is random, so means zygotes with different combinations of chromosomes are produced

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10
Q

how are gametes formed

A

meiosis

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11
Q

what is meiosis

A

type of cell division that takes place in reproductive organs

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12
Q

what happens to diploid cells during meiosis

A

they become haploid

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13
Q

what happens before meiosis begins

A

DNA unravels and replicates, so there are 2 copies of each chromosome called chromatids, them the DNA condenses to form double-armed chromosomes each made from two sister chromatids

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14
Q

what are sister chromatids joined by

A

centromere

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15
Q

what happens during meiosis I (first division)

A

chromosomes arrange themselves into homologous pairs which are then seperated, halving the chromosome number

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16
Q

what are homologous pairs

A

chromosomes in the pair are the same size and have the same genes (but could have different versions of the genes)

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17
Q

what are different versions of the same gene called

A

alleles

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18
Q

what happens during meiosis II (second division)

A

the pairs of sister chromatids that make up each chromosome are seperated through the centromere dividing

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19
Q

what are produced from meiosis

A

4 haploid cells that are genetically different

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20
Q

what occurs during meiosis I

A

chromatids can cross over

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21
Q

what does chromatids crossing over produce

A

genetic variation

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22
Q

what occurs during the crossing over of chromatids

A

chromatids swap over and change alleles of the same gene

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23
Q

what does the crossing over mean for the 4 daughter cells produced

A

each cell has a different chromatid and so has a different set of alleles

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24
Q

what does independant segregation of chromosomes produce

A

genetic variation

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25
Q

what is independant segregation of chromosomes

A

when the chromosomes pair up randomly in meiosis I, leading to the 4 daughter cells having completely different combinations of the maternal and parental chromosomes

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26
Q

mitosis summary

A

produces 2 daughter cells with same number of chromosomes that are genetically identical

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27
Q

meiosis summary

A

produced 4 daughter cells with half number of chromosomes than parent cells that are genetically different

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28
Q

how many chromosomes do human cells

A

46, 23 pairs

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29
Q

what causes chromosome mutations

A

errors in cell division

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30
Q

what do chromosome mutations lead to

A

inherited conditions (as mutations are passed down through gametes)

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31
Q

examples of chromosome mutations

A

non-disjunction

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32
Q

what is non-disjunction

A

failure of chromosomes seperating properly

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33
Q

what can non-disjunction cause

A

downs syndrome

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34
Q

which chromosome causes downs syndrome

A

the failed seperation of chromosome 21 during meiosis leading to someome having an extra copy

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35
Q

what are mutations

A

changes to the base sequence of DNA

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36
Q

types of errors in the base sequence of DNA that leads to mutation

A

deletion or substitution of bases

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37
Q

what occurs during deletion of bases

A

one base is deleted

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38
Q

what occurs during substitution of bases

A

one base is substitutes with another (swapped)

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39
Q

do substitution of bases change the amino acid coded for

A

not always as some amino acids are coded for by more than one DNA triplet so the substitution could still code for the same amino acid

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40
Q

do deletion of bases change the amino acid coded for

A

yes as the triplets will shift, meaning all the amino acids coded for after the deletion will change

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41
Q

what are mutagenic agents

A

things that cause an increase in the rate of mutation

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42
Q

mutagenic agents examples

A

ultraviolet radiation, ionising radiation, some chemicals and some virus’

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43
Q

what is genetic diversity

A

number of different alleles of genes in a species or population

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44
Q

what increases genetic diversity within a population

A

mutations in the DNA following new alleles, different alleles being introduced into a population when individuals from another population migrate into them and reproduce

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45
Q

what is different alleles being introduced into a population when individuals from another population migrate into them and reproduce called

A

gene flow

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46
Q

what does genetic diversity allow to occur

A

natural selection

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47
Q

what is a genetic bottleneck

A

event that causes a big reduction in a population (e.g. death before reproduction)

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48
Q

what does a genetic bottleneck do

A

reduces genetic diversity by reducing the number of different alleles in the gene pool

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49
Q

what is a gene pool

A

complete range of alleles in a population

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50
Q

what is a population

A

group of organisms of one species living in a particular habitat

51
Q

example of a recovery from a genetic bottleneck

A

nothern elephant selas went from 50 to 170,000 but has little genetic diversity than it would if htey weren’t hunted by humans

52
Q

what is the founder effect

A

type of genetic bottleneck

53
Q

what does the founder effect describe

A

what happens when a few organisms from a population start a new colony and there are only a small number of different alleles in the initial gene pool

54
Q

what might occur due to the founder effect

A

high number of genetic disease, as an allele that was once rare would become more common (e.g in the Amish)

55
Q

what does natural selection do

A

increases advantageous alleles in a population

56
Q

what is natural selection

A

when individuals that contain a beneficial allele are more likely to survive and are therefore more likely to reproduce and pass the allele on, meaning the frequency of the beneficial allele increases through generations which allows species to evolve

57
Q

what does natural selection lead to

A

better adapted populations

58
Q

what are the types of adaptations

A

behavioural, physiological, anatomical

59
Q

what are behavioural adaptations

A

ways an organism acts that increases its chance of survival or reproduction (e.g possums playing dead)

60
Q

what are physiological adaptations

A

process inside an organisms body that increase its chances of survival (e.g brown bears hybernating to conserve energy)

61
Q

what are anatomical adaptations

A

structural features of an organisms body that increase its chance of survival (e.g whale blubber)

62
Q

what are the types of natural selection

A

stabilising selection or directional selection

63
Q

what shows stabilising selection

A

human birth weight

64
Q

what is stabilising selection

A

individuals with alleles for characteristics work towards the middle of the range are more likely to survive and reproduce

65
Q

when does stabilising selection occur

A

when the environment isnt changing

66
Q

what does stabilising selection reduce

A

the range of possible characteristics

67
Q

how does human birth weight show stabilising selection

A

small babies = less likely to survive (hard to maintain body temp) big babies = less likely to survive (hard to give birth to) medium babies = perfect

68
Q

what shows directional selection

A

antibiotic resistance

69
Q

what is directional selection

A

individuals with alleles for characteristics of an extreme type are more likely to survive and reproduce

70
Q

what could directional selection survival be in response to

A

an environmental change

71
Q

how is antibiotic resistance an example of directional selection

A

bacteria with resistant allele = survive and reproduce so pass onto offspring

72
Q

interpreting data on the effects of selection

A

describe what the data shows (which type), suggest cause

73
Q

testing effects of antibiotics using agar plates

A

liquid broth, sterile equipment, incubation at 25 degrees, inhibition zone

74
Q

why are aseptic techniques used

A

to prevent contamination of cultures by unwanted microorganisms

75
Q

what are aseptic techniques

A

disinfectant, flame, minimise time spent in open

76
Q

what does phylogeny tell us

A

the evolutionary history of organisms and how closely related organisms are

77
Q

what is phylogeny

A

the study of the evolutionary history of organisms

78
Q

branches of phylogeny tree

A

first branch = common ancestor of all family members, now extint, close branches = closely related

79
Q

what is taxonomy

A

science of classification, naming organisms and organising them into groups to make them easier to identify and study organisms

80
Q

how many groups are there of organising organisms

A

8

81
Q

how are these groups arranged

A

hierachy, largest at the top and smallest at the bottom

82
Q

order of the group

A

domain, kingdom, phylum, class, order, family, genus, species

83
Q

what is a species

A

a group of similar organisms able to reproduce to give fertile offspring

84
Q

what is the nomenclature

A

naming system

85
Q

what is nomenclature used for classification

A

binomial naming system

86
Q

what is the binomial naming system

A

first part = genus name and has capital letter, second part = species and lower case, always written in italics or underlined if hand written

87
Q

what is courtship behaviour

A

species specific, carried out by organisms to attract a mate of the right species

88
Q

what does courtship behaviour do

A

prevents interbreeding and so makes mating more successful

89
Q

how can courtship behaviour be useful in classification

A

similar courtship behaviour means more closely related

90
Q

courtship behaviour examples

A

fireflies = pulses of light
crickets = sounds
male peacocks = colourful tails
male butterlflies = chemicals

91
Q

technologies useful for clarifying evolutionary relations

A

genome sequencing, comparing amino acid sequence, immunological comparisons

92
Q

what is genome sequencing

A

determining entire base sequence of an organisms DNA

93
Q

using genome squencing in classification

A

closely related species = higher percentage of similarity in DNA base order

94
Q

using comparing amino acid sequence in classification

A

related organisms have a similar DNA sequence and so similar amino acid sequence in their proteins

95
Q

using immunological comparisons in classification

A

similar proteins will bind to the same antibodies, so if they bind = animals are closely related

96
Q

how do we measure genetic diversity

A

comparing DNA base sequences (different alleles of the same gene have slightly different DNA base sequences) and comparing amino acid sequences (different alleles have different mRNA sequences so produce different proteins)

97
Q

how is variation caused

A

genes, environment or both

98
Q

what is variation

A

the differences that exists between individuals

99
Q

how do genes cause variation

A

genes have different alleles that cause variation

100
Q

examples of environment differences causing variation

A

climate, food, lifestyle

101
Q

example of genes and environment causing variation

A

genes decides how tall an organism can grow, but nutrient availability affects how tall the organism actually grows

102
Q

how to study variation

A

use a random sample of a population

103
Q

why only use a sample

A

too time-consuming or impossible

104
Q

why does a sample have to be random

A

to ensure the sample isnt biased

105
Q

how to see if the variation observed is due to chance

A

analyse the results statistically

106
Q

method to look for variation between samples

A

finding the mean

107
Q

how do you find the mean

A

total of all the values in your data / number of values in the data (add all the data together and divide by how many there are)

108
Q

how to find information about variation within a sample

A

standard deviation

109
Q

what does standard variation tell you

A

how much the values in a single sample vary , close to mean = doesnt vary (small standard deviation) spread from mean = varies (large standard deviation)

110
Q

what do error bars using standard deviation tell you

A

how spread out the data is (large error bar = spread out, small error bar = not spread out)

111
Q

what is biodiversity

A

the variety of living organisms in an area

112
Q

what is a habitat

A

the place where an organism lives

113
Q

what is a community

A

all the populations of different species in a habitat

114
Q

what does high biodiversity mean

A

lots of different species

115
Q

what are the layers of biodiversity

A

local and global

116
Q

what is local biodiversity

A

variety of different soecies living in a small habitat that’s local to you

117
Q

what is global biodiversity

A

variety of species on earth, greater at the equator and decreases towards the poles

118
Q

what is the index of diversity

A

method of measuring biodiversity

119
Q

what is species richness

A

a measure of the number of different species in a community

120
Q

how to work out species richness

A

taking a random sample and counting the number of different species

121
Q

how to calculate index of diversity

A

N(N-1)/totaln(n-1)
N=total of all organisms
n=total in one species

122
Q

which agricultural practices can reduce biodiversity (5)

A

woodland clearance (recudes tree habitats)
hedgerow removal (removes habitats)
pesticides (kills organisms)
herbicides (reduces plant diversity and removes habitats)
monoculture (only one type of habitat)

123
Q

conservation scheme examples (3)

A

legal protection for endangered species, protected areas, environmental stewardship scheme that encourages farmers to conserve biodiversity

Biology aqa AS (7 decks)

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