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Biology Paper 2 > Classification and Evolution > Flashcards

Classification and Evolution Flashcards

1
Q

Define classification

A
  • Placing living organisms into groups
  • Based on similarities and differences
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2
Q

How are species classified?

A
  • Morphology (observable features)
  • Biochemistry e.g. cytochrome C
  • Genes
  • Shared evolutionary past (phylogeny) - determined through genetic analysis and fossil record
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3
Q

What is a hierarchy of taxa?

A
  • When species are classified into a series of taxa
  • Each taxa contains a larger range of organisms than the one before
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4
Q

List the hierarchy of taxa

A
  • Domain
  • Kingdom
  • Phylum
  • Class
  • Order
  • Family
  • Genus
  • Species

Did King Philip Came Over For Good Soup

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5
Q

What is the mnemonic for hierarchy of taxa?

A

Did King Philip Come Over For Good Soup

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6
Q

What are the 3 domains?

A

Archaea, Eubacteria, Eukaryote

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7
Q

What are the 5 kingdoms?

A

Prokaryotae, Protocista, Fungi, Plantae, Animalia

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8
Q

Explain why viruses are not assigned to any domains

A

Viruses are not considered to be living organisms

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9
Q

Explain why viruses can be considered to be non-living

A
  • No metabolism
  • Cannot reproduce by themselves - need a host cell
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10
Q

What is the binomial system?

A

System used to name species

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11
Q

How is the binomial system used?

A

Genus species

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12
Q

How and why have classification systems changed over time?

A
  • Living organisms classified based on major differences in characteristics.
  • Scientific advances allowed smaller details to be observed.
  • Further advances allowed DNA and proteins to be studied - provided evidence for evolutionary relationships
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13
Q

Explain why prokaryotes are now classified as two separate domains

A

Advances in biological techniques found
- rRNA differs
- Cell walls differ (peptidoglycan not found in archaea)

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14
Q

Define species

A

Group of organisms that can reproduce with one another and produce fertile offspring

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15
Q

What is the purpose of using classification systems?

A
  • Allows easier identification of a species
  • Can help identify common ancestors
  • It is universal so avoids problems of local names of organisms
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16
Q

What could cause a species to be reclassified?

A

New evidence showing that a previous taxon contains species that have evolved from different ancestral species

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17
Q

Give the molecule evidence that can be used to identify organisms as belonging to a different species

A
  • Genetics (DNA)
  • RNA
  • Cytochrome C (protein found in living organisms)
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18
Q

How is it possible to confirm over a long period of time if organisms belong to the same species?

A
  • Interbreed organisms
  • Determine if offspring are fertile
  • If offspring are infertile then different species
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19
Q

What is the function of a dichotomous key?

A
  • Used to identify plant and animal species
  • Based on their charachteristics
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20
Q

Define phylogeny

A

Phylogeny is the evolutionary relationships between organisms

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21
Q

Explain how phylogeny is related to classification

A
  • Phylogeny is the basis of scientific classification
  • The closer the evolutionary relationship, the closer the taxonomic grouping
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22
Q

Define phylogenic tree

A
  • Tree diagrams that show the most probable sequence of evolutionary divergence
  • A branch ‘node’ contains organisms that are related and must share common ancestry
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23
Q

How can phylogenic trees be used to discover evolutionary relationships?

A
  • Used to find out how closely related organisms are
  • Used to find the probable sequence in which the groups split
  • A % difference in amino acid sequence used to estimate a time scale
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24
Q

How does phylogenic approach differ from biological species concept?

A
  • No need to test for interbreeding (to see if offspring fertile)
  • Seeks to determine common ancestor
  • Can apply to organisms that reproduce asexually
  • Can apply to extinct organisms
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25
Q

What is the advantage of phylogenic classification?

A
  • Takes into account evolutionary relationships that are not obvious from characteristics
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26
Q

What is the biological definition of the term evolution?

A

The cumulative change in the heritable characteristics of a population

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27
Q

Define the theory of evolution

A
  • Many species extinct/alive came from simple life forms which first developed more than 3 billion years ago
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28
Q

Which two scientists first published the theory of evolution?

A

Darwin and Wallace

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29
Q

Describe the work of Lyell, Darwin and Wallace

A
  • Lyell - suggested fossils were evidence of animals that lived millions of years ago
  • Darwin - came up with theory of evolution by studying finches in Galápagos islands
  • Wallace - came up with theory of evolution by natural selection in Borneo
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30
Q

Summarise Charles Darwin’s finding on the HMS Beagle

A
  • Visited Galápagos islands
  • Large seeds require large beak finches
  • Small seeds require small beak finches
  • Medium beak finches feed on a variety of size seeds
  • Beak size = heritable characteristic
  • Climate on Galapagos varied a lot - in droughts only larger seeds survive
  • Darwin found a significant drop in small beak finches after drought
31
Q

Explain how evolution may happen in response to an environmental change

A
  • Variation in population due to mutation
  • More offspring are produced than can survive
  • Struggle for survival / survival of fittest
  • Those with most favourable alleles more likely to survive and reproduce
  • Favourable alleles passed on to offspring
  • Frequency of favourable alleles increases in population over many generations
  • This is evolution by natural selection
32
Q

Outline the types of evidence that can be used to support the theory of evolution

A

Fossils
- Show species changed over time

Comparative biochemistry
- Show common ancestry and when species diverged

Comparative anatomy (homologous structures)
- e.g. pentadactyl limb
- Show common ancestry

33
Q

Why is natural selection now more widely accepted by scientists than it was in the 19th Century?

A
  • Fits current evidence
  • More evidence since nineteenth century
  • Development of scientific techniques (e.g. DNA sequencing)
34
Q

Define fossil

A

Remains of plants and animals found in rocks

35
Q

How are fossils formed?

A

Hard parts of plants and animals which do not decay
- Conditions for decay are absent e.g. low temperatures, no oxygen
- Preserved traces e.g. plant rootlets, footprints

36
Q

Why is the fossil record incomplete?

A

Many organisms are soft bodied
- Decompose before they can fossilise
- Conditions for fossilisation often not present
- Many fossils destroyed by natural processes or not yet discovered

37
Q

Outline how fossil records can provide evidence for evolution

A
  • Fossils show changes over time
  • Fossils can be dated e.g. with radioisotopes
  • Simplest / most different from modern species found in oldest rocks
  • Shows relationships between species
  • Many fossilised organisms no longer exist
  • DNA extracted from some fossils can be compared with living organisms
38
Q

Explain how comparative biochemistry provides evidence of evolution

A

Study of similarities and differences in proteins and DNA of an organism
- Changes in molecules can help identify evolutionary links
- e.g. cytochrome c, ribosomal RNA
- Species that are closely related have the most similar DNA and proteins

39
Q

Define homologous structures

A

Structures which have evolved from the same part of a common ancestor
- e.g. pentadactyl limb

40
Q

Describe how the pentadactyl limb can be used as evidence for evolution

A

4 groups of vertebrates have pentadactyl limb: amphibians, mammals, reptiles and birds
- Pentadactyl limb has multiple functions
- All groups have a common ancestor
- Through evolution the limb became adapted to suit different uses - adaptive radiation

41
Q

Define divergent evolution

A

Different species have evolved from a common ancestor
- Each with a different set of adaptive features

42
Q

Outline the process of adaptive radiation

A

Ancestral species occupies new environment
- Different members of the species exposed to different selection pressures
- Gives rise to new species that share common structures adapted to new environment
- e.g. pentadactyl limb, Galapagos finch beaks

43
Q

Define variation

A

Differences between organisms

44
Q

Define interspecific variation

A

Variation between members of different species e.g. numbers of legs

45
Q

Define intraspecific variation

A

Variation within a species e.g. hair colour

46
Q

Give the factors that cause variation

A

Genetic variation - differences in the genetic material inherited
Environmental variation

47
Q

List the causes of genetic variation

A
  • Different alleles
  • Mutation
  • Meiosis
  • Sexual reproduction
  • Chance
48
Q

How can different alleles lead to genetic variation?

A

Genes have different alleles - individuals in a species population may inherit
different alleles of a gene

49
Q

How can meiosis lead to genetic variation?

A

Crossing over of non-sister chromatids leads to mixing of genetic information
- Independent assortment leads to gametes of an individual showing variation

50
Q

Give an example of a characteristic that shows both environmental and genetic causes

A
  • Skin colour
  • Height
51
Q

Explain why genetic variation is more common in organisms that reproduce sexually

A
  • DNA can only be altered by mutation
  • Individuals produced by asexual reproduction are clones
  • Meiosis does not take place
52
Q

What two types of characteristics caused by variation exist?

A

Discontinuous and continuous

53
Q

Define discontinuous variation

A

Usually affected by genes alone (not the environment)
- e.g. blood groups are A, AB, B, O

It can only take particular values

Categoric

54
Q

Define continuous variation

A

May be affected by both genes and the environment
- e.g. height and weight

Can take range of values

Not categoric

55
Q

State the pattern of inheritance that contributes to continuous variation

A

Polygeny (more than one gene)

56
Q

Define polygenic inheritance

A

Continuous variation which depends on the effect of more than two genes

57
Q

Explain how polygenic inheritance gives rise to continuous variation

A

Example: Human skin colour
- Can vary from pale to very dark
- Skin colour controlled by alleles from several genes
- No alleles are dominant (alleles are co-dominant)
- Many different possible combinations of alleles
- Skin colour controlled by combination of alleles

58
Q

When plotted onto a graph, what shape does continuous data usually produce?

A

Normal distribution curve (bell-shaped)

59
Q

What is standard deviation a measure of?

A

How spread out data is
The greater the SD, the greater the spread

60
Q

What does a large SD tell you about the the variation in a population?

A

Large SD = large amount of variation

61
Q

Define adaptation

A

Characteristics that increase an organism’s chance of survival

62
Q

List three types of adaptations

A

Anatomical
- Physical features

Behavioral
- The way an organism acts

Physiological
- Process that takes place inside an organism

63
Q

Examples of anatomical adaptations

A

Camouflage - allows organism to blend in
Teeth - sharp teeth kill prey and tear meat

64
Q

Define innate behaviour

A

Ability inherited through genes e.g. spider spinning web

65
Q

Define learned behaviour

A

Learnt from experience and observing others e.g. using tools

66
Q

Give examples of behavioral adaptations

A

Survival behaviors e.g. playing dead
Migration
Courtship e.g. feather display

67
Q

Examples of physiological adaptations

A

Poison production
Water holding e.g. cactus

68
Q

Define analogous structures

A

Features that have adapted to perform same function
Have different genetic origin e.g. tall fins of whales and fishes

69
Q

State the difference between analogous and homologous structures

A

Analogous structures - have adapted to perform same function but have different origin

Homologous structures - appear superficially different but have same underlying structure

70
Q

Define convergent evolution

A
  • When unrelated species share similar traits
  • Occurs when organisms adapt and evolve to similar environments or selection pressures
71
Q

How do marsupial moles and placental moles provide evidence for convergent evolution?

A

They have analogous structures
- Both burrow through soft soil to find insects, both have velvety fur for smooth movement through soil

72
Q

Define selection pressures

A

Factors that affect an organism’s chance of survival or reproductive success

73
Q

Outline the process of natural selection

A
  • Variation due to mutation
  • Change in selection pressures
  • Those with most favourable alleles more likely to survive and reproduce.
  • Less well adapted organisms die or fail to reproduce
  • Advantageous alleles passed to offspring
  • Frequency of favourable alleles increases over generations
  • Can eventually lead to evolution of a new species
74
Q

Prokaryotae features

A
  • Unicellular
  • Peptidoglycan cell wall
  • No nucleus or membrane-bound organelles

Biology Paper 2 (13 decks)

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