Chapter Eight: Evolution Flashcards

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1
Q

What is evolution?

A

Is the change in genes of a population on earth over time

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2
Q

What is microevolution?

A

Refers to changes in one gene pool of a population over generations

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3
Q

What is macroevolution?

A

Refers to speciation, the formation of an entirely new species

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4
Q

Relate individuals and populations to evolution

A

Individuas can never evolve

A population is the smallest group that can evolve

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5
Q

What is a population

A

Consists of all the members of one species in one place

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6
Q

What does a fossil record show?

A

The existence of species that are extinct or have evolved into other species

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7
Q

What age do radioactive dating and half life suggest the earth is

A

4.6 billion years old

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8
Q

What are the oldest fossils?

A

Prokaryotes

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9
Q

What are transitional fossils?

A

Fossils that link older extinct fossils to modern species

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10
Q

What are homologous structures?

A

Having different functions in different species, but same internal structure; suggesting common ancestry

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11
Q

What are analogous structures?

A

Same function, but different underlying structures; suggesting adaptation to similar environment, but NOT common ancestry

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12
Q

What are vestigial structures?

A

Small parts of structures that used to fully exist before. They suggest that anatomy of animals has evolved, such as the appendix which is no longer needed as our diets have changed

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13
Q

What is comparative biochemistry?

A

Organisms that have a common ancestor have common biochemical pathways

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14
Q

What is comparative embryology?

A

Closely related organisms go through similar embryonic stages because they have a common ancestor

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15
Q

What are 6 evidences of evolution?

A

1) fossil record
2) comparative anatomy
3) comparative biochemistry
4) comparative embryology
5) molecular biology
6) biogeography

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16
Q

What process do all aerobic organisms use to respire and what polypeptide do they need for that?

A

They use ETC

They need cytochrome c

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17
Q

Cytochrome c is present in all aerobic organisms but does differ in between species. What causes this?

A

Comparison of the amino acid sequence

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18
Q

What does the theory of continental drift state?

A

250 million years ago countries were locked together as a supercontinent called Pangaea, which separated slowly into 7 different continents

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19
Q

How can study of location be useful to study evolution?

A

Presence of fossils

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20
Q

What was Lamarks theory?

A

Individual organisms change in response to their environment and inherit acquired characteristics

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21
Q

Explain in detail the essence of Dawins theory of natural selection (4)

A
  • Populations tend to grow exponentially, to overpopulate and exceed their resources. •Overpopulation results in competition and struggle for existence
  • In any population there exists variation and unequal ability of individuals to survive and reproduce
  • Survival of the fittest! Only the best-fit survive and get to pass on their traits. This results in evolution, advantageous traits accumulate in a population
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21
Q

What is Dawins degree for fitness?

A

Measured by the ability of an organism to survive and reproduce in its environment

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22
Q

What was the weakest part of Dawins theory? How is it now explained?

A

Sources of diversity in a population.

Genetics now explain that (variation from crossover, and random line up on metaphase plate, and mutations)

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23
Q

How did the giraffe “get” it’s long neck?

A

Ancestral giraffes were all short-necked, although the length did vary between individuals. As population and competition increased, the talkers ones had a better chance of survival. Over time only long-necked ones increased and others were eliminated. NO ANIMALS NECK GREW LONGER, THE AVERAGE LENGTH OF THE NECK IN THE POPULATION INCREASED

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24
Q

How did the giraffe “get” it’s long neck?

A

Ancestral giraffes were all short-necked, although the length did vary between individuals. As population and competition increased, the talkers ones had a better chance of survival. Over time only long-necked ones increased and others were eliminated. NO ANIMALS NECK GREW LONGER, THE AVERAGE LENGTH OF THE NECK IN THE POPULATION INCREASED

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25
Q

Explain industrial melanism and peppered moths

A

At first, most were white, only some dark. White moths camouflaged with their environment and Dark’s ones were easy prey. But with industrialization soot polluted the environment and made everything black. This meant dark moths were camouflaged and had the selective advantage. With time, dark ones replaced white ones. NO MOTH CHANGED COLOR, THE FREQUENCY FOR THE DARK ALLELE INCREASED

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26
Q

Relate evolution and drugs such as antibiotics

A

Antibiotics killed susceptible bacteria and the rest were resistant. THE ANTIBIOTIC DID NOT INDUCE MUTATIONS FOR RESISTANCE. The resistant survivors pass on the traits to make a population resistant

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27
Q

Why is AIDS so hard to cure?

A

The AIDS virus has the ability to rapidly mutate and evolve and become resistant to drugs. Susceptible viruses become deactivated but the survivors create an entire population of resistant viruses.

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28
Q

Why do some vaccines need to be developed yearly?

A

The viruses evolve rapidly

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29
Q

The type of natural selection, frequency of inherited traits, depends on __

A

Which phenotypes of a population are favoured

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30
Q

What is stabilizing selection?

A

Eliminates the extremes (they just die) and favors more common intermediate forms

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31
Q

What is disruptive or diversifying selection?

A

Increasing the no. of extreme types at tge expense of intermediate forms

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32
Q

What is balanced polymorphism?

A

Results from disruptive selection where in the short term 2 or more phenotypes coexist in a population

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33
Q

Disruptive selection in the long term results in …

A

The formation of 2 entirely new species

34
Q

What is directional selection?

A

With changing environmental conditions, one phenotype replaces another in the gene pool

35
Q

What are the 3 sources of variation in a population?

A
  • mutation
  • genetic drift
  • gene flow
36
Q

What are mutations?

A

Changes in genetic material and the raw material for evolutionary change

37
Q

What type of mutation can introduce a new allele into a population?

A

Single point mutation

38
Q

What is genetic drift?

A

Change in the gene pool due to CHANCE

39
Q

What is the bottleneck effect?

A

When natural disasters reduce population size nonselectively, resulting in loss of genetic variation. The population becomes smaller and not representative of the original one. Certain alleles may under or over represented compared with the original population

40
Q

What is the founder effect?

A

When a small population breaks away from a larger one to colonize a new area, it is most likely not genetically representative of the original one, as rare alleles may be overrepresented (due to breeding in extreme isolation between close communities)

41
Q

What is gene flow?

A

Movement of alleles into or out of a population, as a result of migration of fertile individuals or gametes

42
Q

What is population stability?

A

A stable, non-evolving population, that is, one in which allele frequency does not change in any course of time
(eg 0.5 allele frequency for a trait, if population is not evolving, after 1000 years it will be 0.5)

43
Q

What is another phrase for the population stability theorem?

A

Hardy-Weinberg Equilibrium

44
Q

What are the 5 Hardy-Weinberg characteristics that must be true for a stable population?

A
  1. THE POPULATION MUST BE VERY LARGE
  2. THE POPULATION MUST BE ISOLATED FROM OTHER POPULATIONS
  3. THERE MUST BE NO MUTATIONS IN THE POPULATION
  4. MATING MUST BE RANDOM
  5. THERE MUST BE NO NATURAL SELECTION
45
Q

Explain the 1st Hardy-Weinberg characteristic

A
  1. THE POPULATION MUST BE VERY LARGE. Because in a small one the smallest change in the gene pool will have a major effect on in allelic frequency. If a large one the small change will be diluted and there will be no change in allelic frequency
46
Q

Explain the 2nd Hardy-Weinberg characteristic

A
  1. THE POPULATION MUST BE ISOLATED FROM OTHER POPULATIONS. There should be no migration of organisms into and out of the gene pool because that would alter the allelic frequencies
47
Q

Explain the 3rd Hardy-Weinberg characteristic

A
  1. THERE MUST BE NO MUTATIONS IN THE POPULATION. A mutation in the gene pool could alter the allelic frequency or introduce a new allele
48
Q

Explain the 4th Hardy-Weinberg characteristic

A
  1. MATING MUST BE RANDOM. If individuals select mates, they will be better fit and have a reproductive advantage and the population will evolve
49
Q

Explain the 5th Hardy-Weinberg characteristic

A
  1. THERE MUST BE NO NATURAL SELECTION. Because it causes changes in relative frequencies of alleles in a gene pool
50
Q

What is the Hardy-Weinberg equation used for?

A

To calculate frequency of an allele in a population

51
Q

What is the Hardy-Weinberg equation

A

p+q=1
(p^2)+(2pq)+(q^2)=1
Where p is dominant and q is recessive

52
Q

What do each part of the equation stand for?

A

p^2=AA homozygous dominant
2pq=Aa hybrid
q^2=aa homozygous recessive

53
Q

What is a species?

A

A population whose members have the potential to interbreed in nature and produce fertile offspring

54
Q

How do fragmentation and isolation foster in formation of new species?

A

The groups are subjected to selective pressures in their environments. With time the groups would have changed so much that they would not interbreed when reintroduced

55
Q

What are the 6 isolating factors?

A

1) geographic isolation
2) polyploidy
3) habitat isolation
4) behavioral isolation
5) temporal isolation
6) reproductive isolation

56
Q

What is geographic isolation

A

When a species is separated by a natural barrier

57
Q

What is polyploidy

A

A type of mutation caused by errors in meiosis, instead of being haploid/diploid they may be tetrapliod or even larger. Such polyploid organisms cannot breed with nonpolyploid ones

58
Q

What is habitat isolation

A

When two species live in the same area but encounter eachother rarely (ie land and water)

59
Q

What is behavioral isolation

A

It occurs when animals become isolated due to some change in behavior by one group

60
Q

What’s temporal isolation

A

It refers to time, such as as to when different organisms of one species sexually mature and become divided into 2 populations.
(eg summer and winter of growing season)

61
Q

What is reproductive isolation

A

Closely related species may not be able to mate because of anatomical incompatibility (eg size)

62
Q

What is divergent evolution?

A

When a population becomes isolated and is exposed to selective pressures and evolves

63
Q

Suggest an evidence of divergent evolution

A

Homologous structures (different function, same structure)

64
Q

What is convergent evolution

A

When unrelated species occupy the same environment and are subjected to similar selective pressures and show similar adaptations

65
Q

Suggest an evidence of convergent evolution

A

Analogous structures (same function, different structure)

66
Q

What is parallel evolution

A

When 2 related species make similar evolutionary adaptions due to living in similar environments after diverging from a common ancestor

67
Q

What is coevolution?

A

The mutual evolutionary sets of adaptations of two interacting species

68
Q

What is adaptive radiation?

A

Emergence of numerous species from a single common ancestor introduced to an environment

69
Q

What is gradualism

A

A theory of evolution stating organisms descend from a common ancestor gradually over time in a branching fashion, and small changes accumulate to big ones. And that fossils should exists as evidence for every stage of evolution with no missing links. This theory is not accepted as fossil record does not support it

70
Q

What is punctuated equilibrium?

A

It is the favoured theory today. It proposes that new species appear suddenly after long periods of no change. Most likely, a new species arises in a different place and expands it’s range, competing and replacing ancestral species that become extinct

71
Q

Explain how the first cell formed

A

Intense heat, lightning, UV in the atmosphere provided energy for chemical reactions to produce the first organic cell. And due to the lack of free corrosively reactive molecular oxygen the cells created and persisted

72
Q

What is the heterotroph hypothesis ?

A

First cells on earth were anaerobic heterotrophic prokaryotes

73
Q

How did anaerobic heterotrophs form?

A

They absorbed molecules from the surrounding primordial soup as nutrients

74
Q

What is the theory of Endosymbiosis?

A

Eukaryotic cells with nuclei/chlorplasts/mitochondria/etc evolved from prokaryotic cells, as tiny bacteria took up residence in larger prokaryotic cells and performed important functions for the host cell

75
Q

What is the Cambrian explosion?

A

Period of time in which many animals (every major phylum) appeared

76
Q

What followed after animals appeared?

A

They moved from oceans to land, filling every available NICHE as competition for Limited resources increased in oceans and evolved the traits necessary to survive in a dry environment

77
Q

Which characteristics enabled animals to move to land?

A
  • lungs
  • skin to keep them from drying out
  • limbs to move
  • mechanisms for internal fertilization
  • shells to protect and keep eggs from drying out
78
Q

Which characteristics enabled plants to move to land?

A
  • roots that anchor them to soil and absorb water
  • supporting cells to enable them to compete for light
  • vascular tissue to carry water upward
  • waxy cuticle to prevent leaves from dehydration
  • seeds, a protective package for embryo and it’s food
79
Q

Name a few factors leading to extinction

A

Habitat destruction
Environmental change
Interdependence (one extinction leads to another)

80
Q

Permian mass extinction

A

Volcanic eruptions covered large areas with thick lava and emitted CO2, and increased global temperature. Almost wiped out life on earth

81
Q

Cretaceous mass extinction

A

A massive asteroid crashed and caused a huge cloud of debris to billow in the atmosphere, blocking sunlight for months. Caused land and marine extinctions including all dinosaurs except birds

82
Q

Summarise 5 important concepts of evolution

A
  1. It’s not always slow (eg bacterial resistance)
  2. It does not occur at the same rate in all organisms (slower in crabs then humans)
  3. It doesn’t always make organisms more complex (eg starfish is bilateral in embryo, adult is radial)
  4. It occurs in populations, not individuals (eg giraffes)
  5. It is directed by environmental changes (eg streamline to move in the ocean)