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HL Bio > 5 evolution (bioninja summary) > Flashcards

5 evolution (bioninja summary) Flashcards

1
Q

evolution definition

A
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2
Q

what is evolution in terms of genes

A

a change in the allele frequency of a populations gene pool over successive generations

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3
Q

what are the 2 proposed theories of evolution?

A

lamarck – species change via habitual use and disuse (rejected bc no genetic basis)

darwin (and wallace) – species change via natural selection (reinforced by modern genetics)

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4
Q

3 ways genetic variation is maintained in a population

A
  • mutations (gene sequence changes)
  • sexual reproduction (new gene combinations)
  • gene flow (immigration and emigration)
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5
Q

2 ways population variety is altered

A
  • random chance (genetic drift) - variant just so happens to die in chance event
  • directed intervention (natural/artificial selection)
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6
Q

what is speciation?

A

when populations are isolated and the level of genetic divergence gradually increases (the longer the populations are seperated)

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7
Q

what supports speciation?

A

continuous variation over geographical range of related pops – gradual divergence

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8
Q

when does speciation occur?

A

when populations diverge to the extent that they can no longer interbreed and produce fertile, viable offspring

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9
Q

what is a fossil?

A

the preserved remains or trace of a past organism

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10
Q

what is the fossil record

A

the totality of all fossils

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11
Q

what does the fossil record show? (law of fossil sucession)

A

shows that changes have occurred in organisms
– these changes have occurred in a consistent
sequence of development

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12
Q

example of law of fossil succession

A

ferns always appear before flowering plants

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13
Q

transitional fossils definition

A

represent intermediary forms within the evolution of a genus and demonstrate species connections

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14
Q

example of transitional fossils

A

The archaeopteryx links the evolution of birds (wings and feathers) to dinosaurs (jaws and claws)

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15
Q

what is selective breeding? how is it effective?

A

mating of animals with desired characteristics (artificial selection)

changes happen over fewer generations – phenotype extremes are promoted

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16
Q

example of selective breeding

A

Large variation in types of dog breeds

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17
Q

what is the “molecular clock”

A

If a particular gene has a stable mutation rate, the time of evolutionary divergence can be estimated

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18
Q

what are vestigial sturctures

A

Some species show the presence of FUNCTIONLESS or reduced REMNANTS of organs that were once present in ancestors

19
Q

example of vestigial structures

A

whales have a pelvic bone (ancestors were terrestrial)

20
Q

what are homologous structures

A

anatomical features that share common basic structure but have different functions

21
Q

what causes anatomical features to differ

A

adaptive radiation (organisms adapt to different niches)

Closely related species demonstrate greater homology

22
Q

example of homologous structure

A

pentadactyl limb (diff appendages, same bone strcuture)

23
Q

what can be gleaned from comparing embryonic development + examples

A

suggests a common evolutionary pathway

  • All terrestrial animals have non-functioning gill slits
  • Many vertebrate have a primitive tail in early stages
24
Q

what is biogeography

A

Biogeography is the distribution of species across an area

  • Related species will usually be found in close proximity
  • E.g. Monotremes are exclusive to Australia/New Guinea
25
Q

how can exceptions to biogeography be explained?

A

continental drift

26
Q

conditions for natural selection

A
  • genetic variation present
  • competition for survival
  • environmental selection pressures
  • beneficial traits survive and repro = more common
27
Q

key components to natural selection (ICEAGE)

A
  • Inherited variation
  • Competition
  • Environmental selection
  • Adaptations
  • Genotype frequency changes
  • Evolution occurs
28
Q

examples of selection pressures (PANDAS)

A
  • Predator / prey dynamics
  • Abiotic factors (e.g. climate)
  • Nutrient supply (food source)
  • Diseases / pathogens
  • Available resources (e.g. light)
  • Space requirements (habitat)
29
Q

what are adaptations

A

traits that make an individual suited to its environment and way of life

can be structural, behavioural, physiological, biochemical or developmental

30
Q

how do populations evolve according to environmental conditions

A

different adaptations based on the functional position of the org in the enviro in its ecological niche

31
Q

example of adaptation

A

change in beaks of finches on Daphne Major

32
Q

how does binomial nomenclature work

A

proposed by carl linneaus in 1735

two parts
1. genus written first, capitalised
2. species in lower case

33
Q

what is taxonomy

A

classifying organisms based
on shared characteristics (or taxa)
more shared taxa = more closely related

34
Q

taxa order

A

Kingdom = katy
phylum = perry
class = comes
order = over
family = for
genus = grape
species = soda

35
Q

3 main domains of life/classification

A
  • eukarya (all eukaryotic)
  • archaea (prokaryotic extremophiles)
  • eubacteria (pathogenic bacteria)
36
Q

eukarya vs archaea vs eubacteria 4

A

histones: present, present, absent
introns: present, present absent
nucleus: present, absent, absent
ribosome: 80s, 70s, 70s

37
Q

what is natural classfication

A

involves grouping organisms according to common ancestry (rather than by common characteristics)
* allows for species to be identified by their evolutionary
pathways and enables the prediction of traits within a group

38
Q

disadvantage of natural classification

A

taxonomists may need to reclassify groups if new phylogenetic evidence emerges

39
Q

what is a dichotomous key

A

involves sequentially dividing organisms into two categories until every organism is individually identified

40
Q

what is cladistics

A

classifying organisms into groups of species (clades)
* A clade consists of a single common ancestor and all descendants

41
Q

what are cladograms

A

tree diagrams where each branch point represent the
splitting of two new species groups from a common ancestral species
* Each branch point (node) represents a speciation event
* The more nodes between groups, the less related the groups are

42
Q

homologous vs analogous features

A

diff structures // similar structures
diff selection pressures // similar
share common ancestry// do not
divergent evolution // convergent evo
eg. pantadactyl limb // fins (whale, shark)

43
Q

how can molecular evidence be used for cladograms

A

related species = sequences with more similarities
AA sequences accumulate diffs slower than DNA sequence

HL Bio (19 decks)

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