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Biology Year 2 > classification, variation and evolution > Flashcards

classification, variation and evolution Flashcards

1
Q

the different types of variation and their descriptions

A

Continuous: controlled by a number of genes character shows a gradation from one extreme to the other

Discontinuous: controlled by a single gene
no intermediate forms
characteristics are clear cut and easy to tell apart

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2
Q

Heritable variation

A

results from genetic changes due to sexual reproduction

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3
Q

three processes that result in heritable variation

  1. what do these processes generate
A

the mixing of two different parental genotypes in cross-fertilization

the random assortment of homologous chromosomes in metaphase 1

crossing over between homologous chromosomes during prophase 1

  1. new allele combinations
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4
Q

what generates novel long-lasting variations

A

only mutations

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5
Q

non-heritable variation

A

environmental influences that determine phenotypic variation

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6
Q

what causes non-heritable variation in humans

A

diet
exercise….etc

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7
Q

what causes non-heritable variation in plants

A

temperature
light
availability of inorganic ions

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8
Q

what happens if organisms of identical genotypes are subject to different environmental influences

A

they show considerable variety

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9
Q

interspecific competition
what is this type of competition illustrated by

A

competition between individuals of different species

predator-prey relationships

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10
Q

intra-specific competition

this type of competition is the basis of the origin of species by?

A

competition between individuals of the same species

Natural Selection

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11
Q

if a population reproduces sexually, then it has a large number of variations. true or false

A

true

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12
Q

gene pool

A

all the alleles of all the genes of all the individuals in a population at any one time

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13
Q

allele frequency

A

a measure of the relative frequency of an allele on a genetic locus in a population

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14
Q

under which circumstances does the gene pool remain stable

A

if the environment is stable

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15
Q

what happens in a population if there is a sudden change of the environment

A

some phenotypes become more advantageous than others

they are therefore selected for whilst the disadvantaged phenotypes will be selected against

therefore the gene pool changes over time and certain alleles become more frequent than others

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16
Q

selection pressures

A

external factors that affect the frequency of certain alleles within a gene pool

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17
Q

selection

A

the process by which organisms better adapted to their environment survives and breed, while those less well-adapted fail to do so.

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18
Q

after selection, the better-adapted organisms are …………………… to pass on their ……………………….. to ………………………………

A

more likely
characteristics
succeeding generations

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19
Q

give four examples of selective agents

A

supply of food
breeding sites
climate
human impact

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20
Q

what does the selection pressure determine

A

the frequency of an allele in a gene pool

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21
Q

what is the hardy-weinberg equation for predicting genotype frequencies?

where p^2 represents?
q^2 represents?
2pq represents?

A

p^2+2pq+q^2= 1

the frequency of homozygous dominant alleles

the frequency of homozygous recessive alleles

the frequency of heterozygote alleles

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22
Q

the hardy-weinberg principle suggests that the frequency of dominant and recessive alleles will remain constant in a population if five conditions are true.

what are the 5 conditions?

A

there is a large population

the population is isolated, so there is no emigration and immigration

there is no selection for or against any phenotype

there is random mating throughout the population

there are no new mutations

23
Q

will there be evolution if the conditions under which the hardy-weinberg principles apply do not change?

A

no there would not

24
Q

natural selection

A

refers to when organisms which are better adapted to their environments are likely to survive and reproduce to produce fertile offspring

25
processes leading to natural selection
variation due to new (random) mutations overproduction (the production of a large number of offsprings) struggle for survival, whereby only the fittest survive the individuals that survive reproduce, passing on their characteristics to their offsprings the offspring therefore gain a selective advantage over many generations, individuals that once belonged to the same species may give rise to two different groups, which are significantly distinct to belong to separate species
26
species
a group of similar individuals that are able to interbreed and produce fertile offspring, and it is reproductively isolated from other such groups
27
speciation
features of behaviour, morphology or genetics which serve to prevent breeding between species
28
name factors that can cause changes in the equilibrium of a gene pool
genetic drift mutations natural selection
29
founder effect
when a population is isolated on an island or a new habitat, the founder members are a small sample of the original population
30
how does founder effect cause a genetic drift
the founder members may have very different allele frequencies to the original population by chance so if the population size remains small, they may undergo a genetic drift
31
bottleneck effect
effects resulting from a disaster that drastically reduces population size, like earthquakes and volcanic eruptions
32
types of speciation and their descriptions
2 types allopatric: speciation resulting from geographical features sympatric: speciation resulting from habitat changes, morphology, breeding mechanisms and behavioural changes
33
what happens to the population in allopatric speciation
the population becomes physically split in separate demes
34
adaptive radiation
this is where present day species have all descended from a common ancestor and have over time occupied different niches via natural selection
35
reproductive isolation
when organisms inhabiting the same area become reproductively isolated into two groups where there are no physical barriers
36
give 4 barriers to breeding
temporal or seasonal isolation behavioural isolation mechanical isolation gamete isolation hybrid sterility hybrid unviability
37
seasonal or temporal isolation
when the breeding season or time of activity of two closely related populations don't exactly correspond
38
behavioural isolation
where traits develop which are very specific to closely related species, thereby preventing them from mating
39
morphology
when closely related species are unable to physically mate due to incompatibility between their genitals
40
hybrid sterility
this is when the set of chromosomes from each parent are different and can therefore not pair up in meiosis 1 and produce gametes
41
give an example of a case of hybrid sterility
horses and donkeys reproducing to produce sterile mules horses have 64 chromosomes and donkeys have 62, their offspring has 63 chromosomes mules are sterile because their parental chromosomes cannot pair up in prophase 1 of meiosis 1, because they are not homologous so meiosis in fails and gametes are not produced
42
how do plants deal with the problem of hybrid sterility
plants can reproduce asexually to produce a colony of sterile hybrids occasionally, the hybrids undergo mutations to become polyploid, meaning they double their chromosome set now their chromosomes can pair up in prophase 1 of meiosis, making them a new species of fertile, mutant hybrids
43
biodiversity
the number of species and the number of individuals of each species in a given environment
44
the three main reasons for which biodiversity can vary
succession natural selection human influence
45
ecological succession
the observed process of change in the species structure of an ecological community over time
46
adaptive radiation
this occurs when a species colonises an area with several niches available
47
adaptation
organisms specialising to suit the environment they live in
48
why do organisms adapt
so that they are uniquely able to exploit their own niche thereby ensuring that their niche is different enough to that of others, to avoid competition
49
behavioural adaptation
these are actions by the organism which help them to survive or reproduce
50
physiological adaptation give example of a physiological adaptation
these are internal workings within the organism which helps it to survive or reproduce fish, birds and whales are able to drink salt water, whereas humans cannot
51
a low level of diversity from the simpson's diversity index suggests?
dominance by just one or few species that a change in one species is more likely to affect the others the community is unstable and could be able to withstand change
52
what are the measures taken to ensure the data is accurate when calculating the species density of a grassland
do a random sampling use a reliable number of quadrats identification of species standardisation of techniques sure that the species are not larger than the quadrat
53
a gene's position on a chromosome
locus
54
polymorphism
it results from multiple alleles for the same gene

Biology Year 2 (21 decks)

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