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VCE BIOLOGY > U4A2 > Flashcards

U4A2 Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

gene pool

A

complete set of alleles present within a particular population.

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2
Q

allele frequency

A

proportion of certain alleles in a gene pool, calculated by frequency divided by total.

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3
Q

factors that can influence gene pools

A

mutations
environmental selection pressures
genetic drift
gene flow
artificial selection pressures

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4
Q

mutation

A

permanent changes to DNA sequences

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5
Q

2 categories of mutations

A

point mutations: change to a single nucleotide in a gene
block mutations: change to larger sections of DNA

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6
Q

4 categories of point mutations

A

silent mutations: no effect on amino acid sequence due to genetic code’s degenerate nature
missense mutations: substitute mutations that code for a different amino acid. (sickle cell anaemia)
nonsense mutations: substitute mutations that prematurely end translation of gene’s mRNA
frameshift mutations: alter reading frame of all following nucleotides.

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7
Q

4 categories of block mutations

A

deletion: removal of DNA section
duplication: replication and lengthening of DNA section
inversion: reversal of DNA section
translocation: switching of DNA sections on different chromosomes.

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8
Q

environmental selection pressures

A

factors in the environment that impact an organism’s ability to survive and reproduce

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9
Q

natural selection

A

mechanism through which organisms that are better adapted to their environment have increased chance of surviving and passing on alleles.

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10
Q

4 basic conditions that facilitate natural selection

A

variation: genetic diversity leads to phenotypic differences.
selection pressure: ESP impacts survivability of oragnisms in a population.
selection advantage: ESP aids survivability of certain organisms
heritability: advantageous trait must be heritable, over time allele frequency will increase.

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11
Q

darwin’s 4 observations

A
  • there is phenotypic variation within species
  • offspring tend to inherit the traits of their parents
  • species produce more offspring than required to replace themselves
  • there is struggle to survive
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12
Q

darwin’s 2 inferences

A
  • individuals whose traits increase survivability leave more offspring than other individuals
  • the unequal chance of reproduction will lead to accumulation of favourable traits in the population
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13
Q

genetic drift

A

changes to a population’s allele frequencies due to sudden and random events

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14
Q

2 types of genetic drift

A
  • bottleneck effect
  • founder effect
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15
Q

bottleneck effect

A

large portion of a population is wiped out by a random event, decreasing population size and lowering genetic diversity.

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16
Q

founder effect

A

small unrepresentative sample of individuals seperate from larger population to colonise new region and start a new population.

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17
Q

2 risks of reducing genetic diversity

A
  • inbreeding
  • lower adaptive potential
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18
Q

gene flow

A

introduction/removal of alleles between populations through either migration or inbreeding.

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19
Q

2 types of migration

A

immigration + emigration

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20
Q

speciation

A

process in which populations genetically diverge until they become distinct species.

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21
Q

isolating mechanisms

A

pre- and post-reproductive isolating mechanisms prevent species from interbreeding.

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22
Q

5 pre-reproductive isolating mechanisms

A
  • geographical
  • ecological
  • temporal
  • behavioural
  • structural
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23
Q

geographical isolating mechanism

A

separation by barriers

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24
Q

ecological isolating mechanisms

A

separation by ecological niches or habitats

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25
Q

temporal isolating mechanisms

A

time when individuals are ready to breed differs

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26
Q

behavioural isolating mechanisms

A

mating behaviours differ

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27
Q

structural isolating mechanisms

A

physical characteristics prevent breeding

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28
Q

3 post-reproductive isolating mechanisms

A
  • gamete mortality
  • zygote mortality
  • hybrid sterility
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29
Q

gamete mortality isolating mechanism

A

sperm unable to penetrate ovum

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30
Q

zygote mortality isolating mechanism

A

zygote is not viable

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31
Q

hybrid sterility isolating mechanism

A

offspring is viable but infertile

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32
Q

2 types of speciation

A

allopatric
sympatric

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33
Q

allopatric speciation

A

formation of a new species as a result of a geographical barrier. barriers isolate populations, preventing gene flow.

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34
Q

sympatric speciation

A

formation of a new species located in the same geographical location.

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35
Q

selective breeding

A

changing a population’s gene pool due to humans altering the breeding behaviour of animals/plants to develop a specific trait. (artificial selection)

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36
Q

3 requirements for selective breeding

A
  • variation: genetic diversity leads to phenotypic variation
  • selection pressure: human intervention places artificial selection pressure, only allowing desirable traits to breed
  • heritability: selected trait must be heritable
37
Q

4 bacterial mechanisms against antibiotics developed by mutations

A
  • impermeability (modified cell wall protein)
  • inactivation (addition of phosphate group to antibiotic, reducing ability to fight antibiotics)
  • pumping out (increasing active efflux of drugs)
  • modification (changing protein shape)
38
Q

3 factors that contribute to the formation of antibiotic-resistant bacteria

A
  • inappropriate compliance with a treatment plan
  • inappropriate use of antibiotics
  • widespread use of antibiotics
39
Q

antigenic drift

A

small and gradual changes to genes encoding for surface antigens. mutations accumulate, forming a new virus subtype.

40
Q

antigenic shift

A

sudden and significant changes to genes encoding for surface antigens. 2+ different strains combine when coninfecting the same host, forming a new subtype via viral recombination.

41
Q

fossil record

A

information derived from fossils arranged chronologically.

42
Q

process of fossilisation

A
  • organism remnants are covered by sediment.
  • over time, sediment layers build + compact layer by layer until pressure cements them together to form sedimentary rock.
  • inside the rock, the fossilised remains may be a permineralised, mould or cast fossil.
43
Q

permineralised fossils

A

fossil formed when mineral-rich groundwater deposits minerals into organic material.

44
Q

mould fossil

A

fossil formed when a living thing decomposes underneath sediment, creating a cavity in the shape of the dead organism.

45
Q

cast fossil

A

fossil formed when a mould fossil is filled with sediment

46
Q

trace fossil

A

indirect evidence of an organism’s existence

47
Q

5 conditions that increase the likelihood of fossilisation

A
  • physical protection from scavengers
  • rapid sediment accumulation
  • constant cool temperatures
  • low oxygen availability
  • low light exposure
48
Q

relative dating

A

comparing its position to other fossils/rock in surrounding rock layers

49
Q

law of fossil succession in relative dating

A

fossils closer to the surface must be younger than those below them.

50
Q

geographical timelines in relative dating

A

scientists are able to assign each layer to a particular period of time based on the law of fossil succession.

51
Q

index fossils

A

help determine the relative age of a new fossil. index fossils have been dated using radiometric methods. they must be distinctive, abundant, distributed worldwide, and existed for a short period of time.

52
Q

transitional fossils

A

exhibit traits common to both an ancestors and its descendants.

53
Q

absolute dating

A

known half-lifes of different radioisoptopes can be used to measure the absolute age of a fossil.

54
Q

3 principles of absolute dating

A
  1. radioisotopes are unstable elements that will break down over time into a more stable product.
  2. on average, the rate of radioisotope breakdown is constant and can be modelled.
  3. half-life describes the amount of time before half of the radioisotope mass is broken down into predictable and stable products.
55
Q

2 common radiometric dating techniques

A
  • carbon-14 to nitrogen-15. half-life is 5730 years. dating period is 1000-50,000 years
  • potassium-40 to argon-40. half-life is 1.3 bya. dating period is 100,000+ years.
56
Q

3 principles of radiocarbon dating

A
  • all living things contain carbon. carbon exists as a ratio of two isotopes: 12C and 14C.
  • when the organism dies, its 14C will decay as it is radioactive. levels of 12C remain the same. the ratio of the two isotopes change.
  • at any time, scientists can measure the amount of 14C in the fossil to determine how long ago it died. 14C:12C ratio is compared to atmospheric ratio.
57
Q

3 categories of structural morphology

A
  • homologous structures
  • analogous structures
  • vestigial structures
58
Q

homologous structures

A

physical features that may look and function very differently from each other but can be shown to have derived from a common ancestor. example of divergent evolution.

59
Q

analogous structures

A

physical structures that serve similar biological functions but are not derived from a common ancestor. example of convergent evolution.

60
Q

divergent evolution

A

process in which a common ancestor evolves into 2+ descendant species

61
Q

convergent evolution

A

process in which distantly related species evolve similar traits over time due to similar selection pressures

62
Q

vestigial structures

A

physical structures that once served a pupose for an organism’s ancestors but, due to changing selection pressures, have lose their original function and are no longer required for survival.

63
Q

2 categories of molecular homology

A
  • amino acid sequences
  • DNA sequences
64
Q

amino acid sequences in molecular homology

A

used to determine how related different organisms are by analysing proteins from conserved genes found in a number of different species.
- haemoglobin
- cytochrome C

65
Q

haemoglobin use in molecular homology

A

can be used to assess the degree of relatedness between species.
carries oxygen around the body.
composed of 4 polypeptie chains, 146 amino acids.

66
Q

cytochrome C use in molecular homology

A

can be used to assess the degree of relatedness between species.
enzyme made by mitochondrial DNA.
composed of 104 amino acids.

67
Q

dna sequences in molecular homology

A

can be used to determine the relatedness between different organisms similar to amino acid sequences.
compare by looking at the order of bases at corresponding gene regions.

68
Q

mitochondrial dna in molecular homology

A

circular, maternally inherited DNA found in mitochondria. composed of 17,000 nucleotides and 37 genes.

69
Q

phylogenetic trees

A

diagrams that show the evolutionary relationships between different species.

70
Q

3 uses of phylogenetic trees

A
  • displaying timeline of lineages
  • displaying relatedness between taxa
  • displaying shared characteristics of different taxa
71
Q

4 components of phylogenetic tree

A
  • root (line at the origin. represents earliest common ancestor.)
  • branch (each line on phylogenetic tree.)
  • node (point where branches split; divergence between taxa.)
  • leaf (end of a branch.)
72
Q

taxon

A

unit of classification in which related organisms are classified.

73
Q

8 categories in the taxonomic classification system

A

kingdom, phylum, subphylum, class, order, family, genus, species.

74
Q

human taxonomic classification

A

kingdom: animalia
phylum: chordata
subphylum: vertebrata
class: mammalia
order: primates
family: hominidae
genus: homo
species: homo sapien

75
Q

key characteristics of primates

A

3D colour vision
large cranium relative to body weight, flexible spines, rotational hips and shoulders, prehensile hands/feet with opposible digit, receptors in fingertips.

76
Q

categories in hominoidea category

A
  • great apes: orangutans, chimps, gorillas, humans.
  • lesser apes: gibbons.
77
Q

key characteristics of hominoids

A

shorter spine, increased brain size, molar teeth in Y5 pattern, longerarms than legs, lack of tail, broader rib cage + pelvis.

78
Q

examples of hominins

A

homo sapiens, homo neanderthalensis, homo erectus, australopithecines.

79
Q

key characteristics of hominins

A

large brain size relative to body size.
cerebrum became more folded, enhanced cognitive ability.
bipedalism

80
Q

pros and cons of having larger brain

A

benefits:
- lower predation vulnerability
- shared mothering
- stable food production
negatives:
- higher energy needs
- higher complexity of childbirth
- larger diet

81
Q

reasons the human fossil record is incomplete

A
  • not all individuals die in fossilisation-promoting conditions
  • rock layers and fossils may erode and disappear over time
  • many rock layers are still inaccessible to paleontologists
82
Q

evidence for human/neanderthal interbreeding

A
  • nuclear DNA studies show 1-4% of the human genome is identical to Neanderthal DNA.
  • 100,000-year-old DNA from Neanderthal fossils contained significant amounts of human DNA
83
Q

homo denisova

A

interbred species occuring 15-44kya.

84
Q

homo luzonesis

A

small-bodied hominin ancestor that lived 50-67kya.

85
Q

2 evolutionary hypotheses

A
  • out-of-africa hypothesis
  • multi-regional hypothesis
86
Q

out-of-africa hypothesis

A

suggests homo sapiens evolved in Africa 200kya before emigrating and replacing existing hominin species in Europe and Asia.

87
Q

evidence supporting out-of-Africa hypothesis

A
  • repeated large-scale analysis of mtDNA shows our lineages can be traced to a common ancestor living in Africa
  • modern-day humans show very little genetic diversity
88
Q

multi-regional hypothesis

A

suggests evolution of modern humans was an ongoing process across all world regions.

89
Q

evidence supporting multi-regional hypothesis

A

morphological clades

VCE BIOLOGY (25 decks)

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