diversity, classification and variation Flashcards
(123 cards)
1
Q
how is DNA passed from one generation to the next
A
gametes
2
Q
what are gametes
A
sperm cells in males, egg cells in females,that join together during fertilisation to form a zygote
3
Q
what does a zygote do
A
divides and develops to from a new organism
4
Q
what do normal body cells have
A
diploid number of chromosomes
5
Q
what does diploid mean
A
contains 2 of each chromosome, one from mother and one from father
6
Q
what do gametes contain
A
haploid number
7
Q
what does haploid mean
A
only one copy of each chromosome
8
Q
what happens during fertilisation
A
haploid sperm fuses with haploid egg to produce diploid cell
9
Q
how does fertilisation create genetic variation
A
it is random, so means zygotes with different combinations of chromosomes are produced
10
Q
how are gametes formed
A
meiosis
11
Q
what is meiosis
A
type of cell division that takes place in reproductive organs
12
Q
what happens to diploid cells during meiosis
A
they become haploid
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
14
Q
what are sister chromatids joined by
A
centromere
15
Q
what happens during meiosis I (first division)
A
chromosomes arrange themselves into homologous pairs which are then seperated, halving the chromosome number
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)
17
Q
what are different versions of the same gene called
A
alleles
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
19
Q
what are produced from meiosis
A
4 haploid cells that are genetically different
20
Q
what occurs during meiosis I
A
chromatids can cross over
21
Q
what does chromatids crossing over produce
A
genetic variation
22
Q
what occurs during the crossing over of chromatids
A
chromatids swap over and change alleles of the same gene
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
24
Q
what does independant segregation of chromosomes produce
A
genetic variation
25
what is independant segregation of chromosomes
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
26
mitosis summary
produces 2 daughter cells with same number of chromosomes that are genetically identical
27
meiosis summary
produced 4 daughter cells with half number of chromosomes than parent cells that are genetically different
28
how many chromosomes do human cells
46, 23 pairs
29
what causes chromosome mutations
errors in cell division
30
what do chromosome mutations lead to
inherited conditions (as mutations are passed down through gametes)
31
examples of chromosome mutations
non-disjunction
32
what is non-disjunction
failure of chromosomes seperating properly
33
what can non-disjunction cause
downs syndrome
34
which chromosome causes downs syndrome
the failed seperation of chromosome 21 during meiosis leading to someome having an extra copy
35
what are mutations
changes to the base sequence of DNA
36
types of errors in the base sequence of DNA that leads to mutation
deletion or substitution of bases
37
what occurs during deletion of bases
one base is deleted
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what occurs during substitution of bases
one base is substitutes with another (swapped)
39
do substitution of bases change the amino acid coded for
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
40
do deletion of bases change the amino acid coded for
yes as the triplets will shift, meaning all the amino acids coded for after the deletion will change
41
what are mutagenic agents
things that cause an increase in the rate of mutation
42
mutagenic agents examples
ultraviolet radiation, ionising radiation, some chemicals and some virus'
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what is genetic diversity
number of different alleles of genes in a species or population
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what increases genetic diversity within a population
mutations in the DNA following new alleles, different alleles being introduced into a population when individuals from another population migrate into them and reproduce
45
what is different alleles being introduced into a population when individuals from another population migrate into them and reproduce called
gene flow
46
what does genetic diversity allow to occur
natural selection
47
what is a genetic bottleneck
event that causes a big reduction in a population (e.g. death before reproduction)
48
what does a genetic bottleneck do
reduces genetic diversity by reducing the number of different alleles in the gene pool
49
what is a gene pool
complete range of alleles in a population
50
what is a population
group of organisms of one species living in a particular habitat
51
example of a recovery from a genetic bottleneck
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
what is the founder effect
type of genetic bottleneck
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what does the founder effect describe
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
what might occur due to the founder effect
high number of genetic disease, as an allele that was once rare would become more common (e.g in the Amish)
55
what does natural selection do
increases advantageous alleles in a population
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what is natural selection
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
what does natural selection lead to
better adapted populations
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what are the types of adaptations
behavioural, physiological, anatomical
59
what are behavioural adaptations
ways an organism acts that increases its chance of survival or reproduction (e.g possums playing dead)
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what are physiological adaptations
process inside an organisms body that increase its chances of survival (e.g brown bears hybernating to conserve energy)
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what are anatomical adaptations
structural features of an organisms body that increase its chance of survival (e.g whale blubber)
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what are the types of natural selection
stabilising selection or directional selection
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what shows stabilising selection
human birth weight
64
what is stabilising selection
individuals with alleles for characteristics work towards the middle of the range are more likely to survive and reproduce
65
when does stabilising selection occur
when the environment isnt changing
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what does stabilising selection reduce
the range of possible characteristics
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how does human birth weight show stabilising selection
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
what shows directional selection
antibiotic resistance
69
what is directional selection
individuals with alleles for characteristics of an extreme type are more likely to survive and reproduce
70
what could directional selection survival be in response to
an environmental change
71
how is antibiotic resistance an example of directional selection
bacteria with resistant allele = survive and reproduce so pass onto offspring
72
interpreting data on the effects of selection
describe what the data shows (which type), suggest cause
73
testing effects of antibiotics using agar plates
liquid broth, sterile equipment, incubation at 25 degrees, inhibition zone
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why are aseptic techniques used
to prevent contamination of cultures by unwanted microorganisms
75
what are aseptic techniques
disinfectant, flame, minimise time spent in open
76
what does phylogeny tell us
the evolutionary history of organisms and how closely related organisms are
77
what is phylogeny
the study of the evolutionary history of organisms
78
branches of phylogeny tree
first branch = common ancestor of all family members, now extint, close branches = closely related
79
what is taxonomy
science of classification, naming organisms and organising them into groups to make them easier to identify and study organisms
80
how many groups are there of organising organisms
8
81
how are these groups arranged
hierachy, largest at the top and smallest at the bottom
82
order of the group
domain, kingdom, phylum, class, order, family, genus, species
83
what is a species
a group of similar organisms able to reproduce to give fertile offspring
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what is the nomenclature
naming system
85
what is nomenclature used for classification
binomial naming system
86
what is the binomial naming system
first part = genus name and has capital letter, second part = species and lower case, always written in italics or underlined if hand written
87
what is courtship behaviour
species specific, carried out by organisms to attract a mate of the right species
88
what does courtship behaviour do
prevents interbreeding and so makes mating more successful
89
how can courtship behaviour be useful in classification
similar courtship behaviour means more closely related
90
courtship behaviour examples
fireflies = pulses of light
crickets = sounds
male peacocks = colourful tails
male butterlflies = chemicals
91
technologies useful for clarifying evolutionary relations
genome sequencing, comparing amino acid sequence, immunological comparisons
92
what is genome sequencing
determining entire base sequence of an organisms DNA
93
using genome squencing in classification
closely related species = higher percentage of similarity in DNA base order
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using comparing amino acid sequence in classification
related organisms have a similar DNA sequence and so similar amino acid sequence in their proteins
95
using immunological comparisons in classification
similar proteins will bind to the same antibodies, so if they bind = animals are closely related
96
how do we measure genetic diversity
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
how is variation caused
genes, environment or both
98
what is variation
the differences that exists between individuals
99
how do genes cause variation
genes have different alleles that cause variation
100
examples of environment differences causing variation
climate, food, lifestyle
101
example of genes and environment causing variation
genes decides how tall an organism can grow, but nutrient availability affects how tall the organism actually grows
102
how to study variation
use a random sample of a population
103
why only use a sample
too time-consuming or impossible
104
why does a sample have to be random
to ensure the sample isnt biased
105
how to see if the variation observed is due to chance
analyse the results statistically
106
method to look for variation between samples
finding the mean
107
how do you find the mean
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
how to find information about variation within a sample
standard deviation
109
what does standard variation tell you
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
what do error bars using standard deviation tell you
how spread out the data is (large error bar = spread out, small error bar = not spread out)
111
what is biodiversity
the variety of living organisms in an area
112
what is a habitat
the place where an organism lives
113
what is a community
all the populations of different species in a habitat
114
what does high biodiversity mean
lots of different species
115
what are the layers of biodiversity
local and global
116
what is local biodiversity
variety of different soecies living in a small habitat that's local to you
117
what is global biodiversity
variety of species on earth, greater at the equator and decreases towards the poles
118
what is the index of diversity
method of measuring biodiversity
119
what is species richness
a measure of the number of different species in a community
120
how to work out species richness
taking a random sample and counting the number of different species
121
how to calculate index of diversity
N(N-1)/totaln(n-1)
N=total of all organisms
n=total in one species
122
which agricultural practices can reduce biodiversity (5)
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
conservation scheme examples (3)
legal protection for endangered species, protected areas, environmental stewardship scheme that encourages farmers to conserve biodiversity
