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Human Biology Unit 4 > Chapter 15 - Evidence For Evolution > Flashcards

Chapter 15 - Evidence For Evolution Flashcards

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1
Q

What is a genome?

A

The complete set of DNA in each cell of an organism

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2
Q

What happens to DNA when speciation occurs?

A

The DNA of the two species will be very similar

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3
Q

What happens to new species as they change due to evolutionary mechanisms?

A

They accumulate more differences in their DNA

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4
Q

How much DNA do humans share with chimps?

A

98%

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5
Q

What is junk DNA?

A

DNA that has no apparent function and serves no purpose

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6
Q

What is an example of junk DNA?

A

Endogenous retroviruses

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7
Q

What is an ERV?

A

A viral sequence of DNA that has become a part of an organisms genome

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8
Q

How does an ERV become inserted into a cell?

A
  • enter cell - copies RNA genome into DNA (reverse transcription)
  • DNA becomes inserted into one of the host cells chromosomes
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9
Q

When does an ERV become endogenous?

A
  • when it inserted into a sperm or an egg cell
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10
Q

How does DNA provide evidence for evolution?

A
  • all species use the same 4 bases that make up DNA
  • the sequence of these bases varies from species to species
  • the more similarities, the more closely related
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11
Q

What is the structure of mitochondrial DNA?

A

Small circular molecules

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12
Q

Where is mtDNA found?

A

Mitochondria

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13
Q

How does mtDNA provide evidence for evolution?

A
  • only inherited through mother’s lineage
  • mtDNA mutates faster than DNA
  • more similarities more closely related through mother’s lineage
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14
Q

How do amino acids provide evidence for evolution?

A
  • all proteins in all species are made up of the same amino acids
  • the sequence of these amino acids varies form species to species
  • the more similarities between the amino acid sequence of a protein of two species the more closely related
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15
Q

What it an ubiquitous protein?

A

Proteins found in a range of organisms and perform the same function

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16
Q

What is an example of an ubiquitous protein?

A

Cytochrome c

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17
Q

How does cytochrome c provide evidence for evolution?

A
  • some sequences of amino acids of cytochrome c are always the same
  • differences also exist between species
  • the less differences that exist the more closely related two species are
18
Q

How does embryology provide evidence for evolution?

A
  • involves comparing the embryos of different species
  • many similarities exist between different species in the embryonic stage eg. Gills - evolved from fish hundreds of millions of years ago
  • the later differences arise, the more closely related species are
19
Q

How do homologous organs/structures provide evidence for evolution?

A
  • involves comparing structures that are similar but used in different ways
20
Q

What are vestigial organs?

A

Organs that may have once been important but have lost or changed their function as a species has evolved

21
Q

How do homologous structures provide evidence for evolution?

A
  • present in ancestors
22
Q

What are some examples of vestigial organs?

A
  • appendix: digesting leaves
  • coccyx: part of the tail
  • wisdom teeth: help grind down plant matter
23
Q

What is a fossil?

A

An preserved trace left by an organism that lived long ago

24
Q

What is stratigraphy?

A

The study of layers, or strata

25
Q

What is an index fossil?

A

A fossilised organism that was widely distributed and only present on earth for a short period of time

26
Q

What does the correlation of rock strata involve?

A

Involves matching similar layers of rock from different areas

27
Q

What does the principle of superimposition assume?

A

Assumes that in layers of sedimentary rock the layers at the top are younger than those beneath them

28
Q

What is a half life?

A

The time required for half of any amount of radio active material to decay into a stable non radioactive material

29
Q

How can index fossils be used to relatively date?

A
  • using index fossils to date relatively is more precise because of their short span of life on earth
  • sedimentary rocks that contain the same index fossils are assumed to be the same age
30
Q

What does fluorine dating involve?

A
  • bone absorbs fluorine ion from water in soil

- the older the bone, the more fluorine it contains

31
Q

Why is it not possible to relatively date fossils from different sites using fluorine dating?

A
  • the bones absorb fluorine from the surroundings

- the concentration of fluoride ions varies between locations

32
Q

What is the half life of carbon 14?

A

5730 years

33
Q

What does carbon 14 decay to?

A

Nitrogen

34
Q

How does carbon 14 dating work?

A
  • living organisms take in carbon
  • an organism stops taking in carbon when it dies
  • the carbon then begins to decay to nitrogen
  • it’s has a half life
  • by comparing the ratio of carbon to nitrogen in the sample and knowing the half life an approximate age of when the organism died can be determined
35
Q

What is the half like of potassium?

A

1.26 billion years (1.3)

36
Q

What does potassium-40 decay to?

A

Argon-40

37
Q

What are limitations of potassium argon dating?

A
  • fossils over 100,000 years old
  • rock being dated must be the same age as the fossil being dated
  • the rock sample must be igneous containing potassium
38
Q

What are some limitation of carbon dating?

A
  • can only be used to date up to 70,000 years
  • sample must be organic and contain carbon
  • is only reliable if the amount of C-14 in the air has been constant
39
Q

What are some limitations of stratigraphy?

A
  • the law of superposition cannot always be applied, as due to the earths shifting tectonics strata can be flipped upside down
  • fossils can be buried by animals after the deposition of sediment and the animal may be younger then the layers above it
40
Q

What are some limitations of index fossils?

A
  • the longer the time period a species lived, the less reliable the index fossil
  • an animal may have lived in different areas at different times
  • an animal may have become extinct in one area before another

Human Biology Unit 4 (5 decks)

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