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Biology Year 12 > Evolution > Flashcards

Evolution Flashcards

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1
Q

What is the theory of evolution?

A

Proposes that all organisms have developed from previous organisms, all life can be traced back to one common ancestor

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2
Q

What is evolution?

A

Process of cumulative, heritable changes in a population over many generations

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3
Q

What is an ancestor?

A

A species from which another species has evolved from

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4
Q

What is a common ancestor?

A

An ancestor shared by different species where there is common genetic code

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5
Q

What are 4 things that are evidence for evolution?

A
  • Fossil record
  • Comparative anatomy
  • Comparative genomics
  • Comparative Biochemistry
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6
Q

What are fossils?

A

Preserved remains or traces of an organism, only portions of the deceased organism (bones, teeth)

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7
Q

Name and explain the 4 processes of fossilisation.

A
  1. Death and decay
    - Organism dies and soft body parts are decomposed or scavenged leaving bones
  2. Deposition
    - Remains are covered rapidly with silt and sand, over time more layers continue to build
  3. Mineralisation
    - Pressure from the covering layers causes hard organic materials to be replaced by minerals
  4. Erosion/Exposure
    - Movement of tectonic plates may displace fossil and return it to the surface for discovery
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8
Q

What are 3 alternative ways a fossil can be preserved other than the original fossilisation method?

A
  • Freezing and dehydration
  • Soft material (eg. ash) falling on impressions
  • Impressions made in sandstone and mudstone
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9
Q

What are 4 conditions for fossilisation to occur?

A
  • Hard body parts are needed, soft body parts don’t usually fossilise
  • Preservation of remains, protection from scavengers and environmental damage
  • High-pressure levels to promote mineralisation
  • Anoxic (low oxygen) to protect against oxygen damage and decomposition
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10
Q

What are 3 biases of fossilisation?

A
  • Fossilisation is rare and very few organisms are preserved
  • Favors organisms with hard body parts
  • Favors organisms that were widespread and existed for a long period before going extinct
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11
Q

What 3 key things does the fossil record show?

A
  1. Organisms in the past are not the same as organisms alive today. (eg phylogeny of a horse)
  2. Organisms have become more complex over time. (eg protists -> invertebrates -> vertebrates)
  3. Shows there are common ancestors, but may have missing links
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12
Q

What are transitional fossils? Give an example.

A
  • Fossils that fill the gaps between ancestor and descendant as they show traits from both ancestor and descendant.
  • Strongly suggestive of evolution as they show the progression form.
  • eg Archaeopteryx. Shows the dinosaur-to-bird transitional form
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13
Q

What is superposition?

A

Suggests that older lock layers are deeper while new layers are closer to the surface

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14
Q

Name and describe 2 methods for dating fossils.

A
  • Comparative dating: How old the rock containing the fossil is compared to the surrounding rock
  • Absolute dating: Involves the use of techniques that can assign a numerical age to a fossil
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15
Q

What are 3 techniques used for absolute dating?

A
  • Radiometric dating: measured with known rates of atomic decay eg. carbon dating
  • Electron spin resonance: Trapped electrons gain magnetic force to environmental radiation over time
  • Luminescence techniques: Measure light emitted from a material
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16
Q

What is comparative anatomy?

A

The study of similarities and differences in the anatomy of different species

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17
Q

What are 3 types of comparative anatomy?

A
  • Homologous structures
  • Embryology
  • Vestigial structures
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18
Q

What are homologous structures?

A

Similar structures in different species have evolved from a common ancestor to serve different functions.

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19
Q

What is embryology?

A

Study of the formation and development of an embryo and phetus

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20
Q

What are 3 things comparing embryonic development shows?

A
  • All terrestrial animals have non-functioning gill slits as early embryos suggesting an aquatic origin
  • Many vertebrates have a primitive tail in embryonic development
  • Closely related species go through similar stages of development
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21
Q

What do similarities in embryonic development suggest?

A

Organisms share a common evolutionary pathway

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22
Q

What are vestigial structures?

A

Structures in organisms that have lost most if not all function in the course of evolution

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23
Q

What is a pentadactyl limb?

A

A hand or foot with 5 fingers or toes, has been modified for a wide variety of functions

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24
Q

What do homologous structures suggest?

A

Common ancestory

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25
Q

What is the evolutionary explanation of the pentadactyl limb?

A

All 4 footed animals have descended from a common ancestor that had a pentadactyl limb, easier to evolve variations of the limb than to recompose whole limb structure

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26
Q

What are 4 examples of vestigial structures in humans?

A
  • Appendix
  • Gall bladder
  • Wisdom teeth
  • Male breast tissue & nipples
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27
Q

What are analogous structures? Give an example.

A

Features of organisms that have a different structure for the same function. eg Shark fins vs penguin fins

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28
Q

What is divergent evolution? Give an example.

A

When related species evolve traits over time away from the common ancestor to create new species. eg common ancestor evolving into lion, puma, cat, leopard

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29
Q

What is convergent evolution? Give an example.

A

When unrelated species evolve similar adaptations to their environments. eg pangolins and numbats, same elongated snout but very distantly related

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30
Q

What is genomics?

A

Study of genes and the interactions within a genome

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31
Q

What is comparative genomics?

A

Using genetic tools to research and compare the genome sequences of different species. The more similar the sequence, the more closely related the species

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32
Q

What 2 molecular methods can be used in comparitive genomics?

A
  • DNA sequencing
  • DNA hybridisation
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33
Q

What is DNA hybridisation?

A
  • Comparing 2 different strands of DNA by denaturing the strands and annealing 2 different strands together, then denaturing to see how similar the DNA of different organisms are.
  • If hybridised DNA requires a higher temp to denature, organisms are more closely related
34
Q

What can scientists do using comparitive genomics?

A
  • Measure the difference between organisms
  • Trace evolutionary relationships
  • Construct phylogenic trees
35
Q

What is comparitive biochemistry?

A

Comparing similarities and differences of amino acid sequences and the proteins produced in different organisms

36
Q

Provide an example of evidence for evolution using comparitive biochemistry.

A

Amino acid chains of common proteins such as haemoglobin found in many organisms are analysed and the similarities and differences in the amino acids provide evidence for evolution

37
Q

Besides evolution, what else can comparitive biochemistry show and how?

A

Shows the relatedness of organisms, determined by the number of differences in ammino acid sequences

38
Q

What are gene pools?

A

Sum of all alleles within a population

39
Q

What are the 4 mechanisms of evolution?

A
  • Mutation
  • Natural selection
  • Genetic drift
  • Gene flow
40
Q

What is genetic drift?

A

Random non-directional change in allele frequencies caused by chance, not selection pressures

41
Q

What is gene flow?

A

Transfer of alleles as a result of migration of individuals from one population to another, due to immigration and emigration of individuals

42
Q

What is the bottleneck effect?

A

Extreme example of genetic drift,w occurs when a population size is drastically reduced (after natural disasters), gene pool of new population is not representative of the original

43
Q

What is the founder effect?

A

Extreme example of genetic drift, occurs when a small group of individuals leave their original population and start a new one in a different location, alleles in new population will be different to original population

44
Q

What are 3 main effects of genetic drift?

A
  • Traits being under or over-represented in new population
  • Traits being lost completely from the gene pool
  • Unusual traits being preserved (allele fixation)
45
Q

What is natural selection?

A

A process where individuals with advantageous inheritable traits survive and reproduce more successfully than other individuals leading to evolutionary change in a population

46
Q

What are the 6 key principles of natural selection?

A
  1. Variation
  2. Over-production
  3. Survival of the fittest (competition)
  4. Higher reproductive rate
  5. Heritability
  6. Allele frequencies change
47
Q

Explain the 1st key principle of natural selection

A

Variation
- Individuals in a population will genetically vary in size, colour, ability to avoid predators, ability to resist disease etc.
-Explains why some individuals survive in a changing environment

48
Q

Explain the 2nd key principle of natural selection

A

Over-production
- Most species produce more offspring than the environment can support
- Not all offspring will survive to reproduce

49
Q

Explain the 3rd key principle of natural selection

A

Survival of the fittest (competition)
- Resources can be limited, competition arises and only the strongest and best-suited individuals with favourable characteristics survive to reproduce

50
Q

Explain the 4th key principle of natural selection

A

Higher reproductive rate
- Individuals that have the desired trait survive to reproduce, having a higher reproductive rate then those without the allele

51
Q

Explain the 5th key principle of natural selection

A

Heritability
- Higher reproductive rate means the desired trait is more likely to be passed on to the offspring

52
Q

Explain the 6th key principle of natural selection

A

Allele frequency changes
- As traits are now inherited, frequencies change in the population as the cycle continues over generations, increasing the frequency of favourable features

53
Q

What are adaptations?

A

Features of an organism that aid their survival by allowing them to be better suited to their environment

54
Q

Give an example of adaptation

A

Peppered moth
- Originally a dark colour, adapted to a lighter peppered colour to camouflage with trees

55
Q

What are 5 types of adaptations? Give examples

A
  • Structural: Physical differences in structure. eg giraffe neck length
  • Behavioural: Differences in patterns of activity. eg possums faking death when threatened
  • Physiological: Variation in detection and response by organs eg. colour perception
  • Biochemical: Differences in molecular composition, cells and enzyme function eg. blood groups
  • Developmental: Variable changes that occur across the lifespan of the organism eg. aging patterns
56
Q

Apply 3 types of adaptions to an echidna

A

Structural: Sharp quills for protection, long snout for eating
Behavioural: Curls into a ball when scared, digs burrows as shelter
Physiological: Sensitive ears to hear ants, tounge can stiffen and penetrate soil (change in blood flow)

57
Q

What is accumulation?

A

Process of particular traits becoming more common over generations

58
Q

Explain selection pressures

A
  • External agents that affect an organism’s ability to survive
  • Can be positive or negative selection pressures
  • May not remain consistent, alters what could be a beneficial trait
59
Q

What are 3 types of selection pressures?

A
  • Resource availability: Presence of food, shelter, mates
  • Environmental conditions: Temp, weather, geographical conditions
  • Biological factors: Predators, pathogens
60
Q

Density-dependent selection pressures

A
  • Predators
  • Availability of resources
  • Nutrient supply
  • Disease
  • Accumulation of wastes
61
Q

Density-independent selection pressures

A
  • Phenomena (natural disasters)
  • Abiotic factors (temp, CO2 levels)
  • Weather conditions (rainfall, storms)
62
Q

What is adaptive radiation?

A

A process where an organism rapidly diversifies into many different forms with different adaption. eg galapogous island finches

63
Q

Give 3 examples of environmental influence on variation

A
  • Flamingos: not born pink, accumulation of red pigment from shellfish
  • Hydrangeas: Acidic soil makes blue flowers, basic soil produces pink flowers
  • Siamese cats: Fur colour is influenced by temperature, low temp on body extremities causes pigment production
64
Q

What is micro-evolution?

A
  • Change in frequency of alleles in a population
  • Changes in gene pool over a relatively short period of time
65
Q

What is macro-evolution

A
  • The process of the evolution of new groups of organisms, consisting of many related species. Occurs through multiple speciation events
  • Major evolutionary changes above the species level of classification
66
Q

What is the process of macro-evolution?

A
  1. Natural selection favours desirable traits, changing populations over time as gene pools accumulate the small changes (micro-evolution)
  2. Eventually a population accumulates enough changes that speciation occurs and a new species can be identified
  3. Rapid speciation events lead to collection of new species or higher classification
67
Q

What are the 5 phases of speciation?

A
  • Variation
  • Isolation
  • Selection
  • High survivability and reproduction
  • Speciation
68
Q

Explain the 1st step of speciation

A

Variation:
- One population, one species
- Variety of characteristics within the population
- Population shares common gene pool

69
Q

Explain the 2nd step of speciation

A

Isolation:
- 2 populations, 1 species
- Barrier forms which prevent the 2 populations interbreeding
- 2 separate gene pools

70
Q

Explain the 3rd step of speciation

A

Selection:
- 2 populations, 2 subspecies (1 species)
- Over generations selection pressures change gene frequencies in both gene pools

71
Q

Explain the 4th step of speciation

A

High survivability & reproduction
- 2 populations, 2 subspecies (1 species)
- Only some organisms with favourable genes survive and reproduce, passing on the trait
- Gene frequencies increase for that trait

72
Q

Explain the last step of speciation

A

Speciation:
- 2 populations, 2 species
- Isolation and selection continue, and gene differences become so large populations can no longer interbreed meaning they are 2 separate species

73
Q

What are the 2 types of speciation?

A
  • Allopatric speciation: Geographical barrier physically isolates populations preventing reproduction
  • Sympatric speciation: Reproductive isolation as a result of genetic abnormality, no physical barrier
74
Q

What are 2 mechanisms of speciation?

A
  • Pre-reproductive
  • Post-reproductive
75
Q

What are 4 types of pre-reproductive speciation mechanisms

A
  1. Geographical features (allopatric)
  2. Temporal mechanisms eg. different breeding seasons (sympatric)
  3. Behavioural mechanisms eg. different mating calls (sympatric)
  4. Morphological mechanisms eg. different reproductive structres (sympatric)
76
Q

What are 3 types of post-reproductive speciation mechanisms

A
  1. Gamete mortality: gametes don’t survive after mating (sympatric)
  2. Zygote mortality: zygote forms but doesn’t survive (sympatric)
  3. Hybrid sterility: offspring develop but cant reproduce (sympatric)
77
Q

What are mass extinctions?

A

Occur rarely, periods with a high rate of extinction

78
Q

3 key points about mass extinction

A
  • Can be natural or human causes
  • Large populations can be more resilient than small ones
  • Reduced genetic diversity due to bottle necks
79
Q

What is conservation?

A

Aims to maintain viable gene pools with consideration of biogeography, reproductive behaviours and population dynamics

80
Q

What are 4 practices of conservation? Explain them.

A
  • Reserves: large protected areas
  • Wildlife corridors: areas of large space allowing organisms to migrate when resources are scarce
  • Transgenic organisms: Designed to resist diseases and extinction
  • Biotechnology: monitoring endangered species, assessing gene pools

Biology Year 12 (9 decks)

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