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BIO 303 > Chapter 3 > Flashcards

Chapter 3 Flashcards

1
Q

Lagerstatte

A

A site with an abundant supply of unusually well-preserved fossils from the same period of time, often including soft tissues.

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2
Q

Burgess Shale

A

A Lagerstatten in Canada that preserved fossils from the Cambrian period. 505 million years ago.

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3
Q

Biomarker

A

Molecular evidence of life in the fossil record. Biomarkers can include fragments of DNA, molecules such as lipids, or isotopic ratios.

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4
Q

Isotopes

A

Different forms of molecules that have different neutron numbers and are used for isotopic dating.

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5
Q

Stromatolites

A

Layered structures formed by the mineralization of bacteria.

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6
Q

Ediacaran fauna

A

A group of animal species that existed between 575 and 535 million years ago.

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7
Q

Chordates

A

Members of a diverse phylum of animals that includes the vertebrates, lancelets, and tunicates. Chordates all have a notochord, a hollow nerve cord, pharyngeal gill slits, and a post-anal tail as embryos.

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8
Q

Trilobites

A

Extinct marine arthropods that diversified during the Cambrian period and gradually died out during the Devonian period.

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9
Q

Notochord

A

a hollow nerve cord

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10
Q

Prokaryotes

A

Microorganisms lacking a cell nucleus or any other membrane-bound organelles. Comprise the Bacteria and Archaea groups.

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11
Q

Tetrapods

A

Vertebrates with four limbs( or descended from vertebrates with four limbs). Living tetrapods include mammals, birds, reptiles, and amphibians.

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12
Q

Teleosts

A

Lineage of bony fish that comprises most living species of vertebrates. Include: goldfish, salmon, and tuna. Can be distinguished by mobility of upper jawbone called premaxillary.

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13
Q

Synapsids

A

Lineage of tetrapods that emerged 300 million years ago and gave rise to mammals. Synapsids can be distinguished by presence of a pair of openings in the skull behind eyes, known as temporal fenestrae.

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14
Q

Hominin

A

Humans and all species more closely related to human than to chimpanzees.

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15
Q

Explain the Darwin and Kelvin dispute:

A

Darwin thought the earth had to be billions of years old for the amount of evolution to take place. Kelvin argued the earth to be 20 million years old based on calculations of the earths cooling.

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16
Q

How old does radiometric dating indicate the earth is?

A

4.6 billion years old

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17
Q

What elemental decay was studied to find the earths age?

A

The beta decay of Rb-87 to Sr-87.

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18
Q

Why was Lord Kelvin’s estimate for the age of the Earth so inaccurate?

A

He failed to account for reactivity.

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19
Q

What is an isochron?

A

A straight line on a graph indicating values measured at a similar time.

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20
Q

Fossils allow us to about an extinct species:

A

morphology, behavior and development.

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21
Q

T or F: Most organisms fossilize

A

F

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22
Q

Example of scanning electron microscopy providing evidence of cellular structure:

A

Structure of melanosomes suggests striking plumage

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23
Q

What helped determine the function of the hadrosaur crest?

A

CAT scans.

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24
Q

What was the structure/ function of the hadrosaur crest?

A

• Crest connected to nasal cavity
– Sound generated by blowing air
• Ears tuned to this frequency

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25
Q

How was the diet of early hominins studied and what did it reveal?

A

Carbon isotopic signatures used to infer diet of early hominins
• C4 plants have lower C13 than C3 plants
– C13/C12 ratio used to infer types of plants eaten

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26
Q

What is the only organism that can produce okenone?

A

Purple sulfur bacteria.

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27
Q

What does their abundance 1.64 billion years ago mean?

A

It supports the hypothesis that the oceans were toxic to organisms like ourselves.

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28
Q

T or F: C4 plants have lower levels of Carbon-13 than C3 plants.

A

True.

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29
Q

How did the fossils of the Burgess Shale form?

A

The animals dropped into anoxic ocean depths and were covered by fine sediment.

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30
Q

How did John Hutchinson and Mariano Garcia determine that Tyrannosaurus rex could not run very fast?

A
  • They compared skeletal structures of Tyrannosaurus rex to modern animals to determine the size of T. rex’s muscles.
  • They tested a model they developed on the biomechanics of running on living animals.
  • They used evolutionary theory to determine the most closely related living organisms to T. rex.
  • they developed biomechanical model of running animals to determine how much force leg muscles of a given size could generate.
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31
Q

Which of the following molecules has not been used as a biomarker: carbon, oxygen, sodium, cellular lipids.

A

Sodium.

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32
Q

Which outcome would you predict if you could compare the isotopes of fossils of two species of human ancestors and found high ratios of C13/C14 in one and low ratios in the other?

A

The species with high ratios likely ate a mixed diet.

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33
Q

What biomarker in rocks suggests early life?

A

carbon

34
Q

What is the oldest claim of life?

A

3.7 billion years ago. The claim is based on carbon in rocks and is controversial.

35
Q

What is accepted date for the first sign of life?

A

3.45 billion years ago, stromatolite bacteria.

36
Q

What constitutes most of life’s diversity?

A

Microbes.

37
Q

Why can’t scientists hope to find conventional fossils from very early in Earth’s history?

A

Plate tectonics have destroyed almost all of the planet’s original surface.

38
Q

What are stromatolites?

A

layered structures formed by the mineralization of bacteria.

39
Q

How sure are scientists about the discoveries related to the earliest signs of life on earth?

A

Fairly sure. Stromatolite formation is a process observable today, and scientists have discovered stromatolite fossils that are 3.45 billion years old.

40
Q

Earliest fossil of bacteria?

A

3.45 byo

41
Q

Earliest fossil of Archaea?

A

3.5 byo

42
Q

Earliest fossil of Eukarya?

A

1.8 byo

43
Q

When does atmospheric oxygen begin to appear in the fossil record?

A

2.45-2.32 byo

44
Q

What was the rise in oxygen levels linked to?

A

the prevalence of photosynthetic cyanobacteria.

45
Q

Fossils of single-celled grazers are important because they are early members of what group?

A

Eukarya

46
Q

Which is NOT true about Archaea?

  • they store their DNA in a nucleus
  • they are single-celled organisms
  • they form a domain of the tree of life
A

They store DNA in their nucleus.

47
Q

When does the oldest multicellular fossil date back to?

A

2.1 billion years ago

48
Q

How did multicellularity arise?

A
  • Evolved independently in different lineages

* Extant organisms provide clues about origin of multicellularity

49
Q

T or F: The transition to multicellular life began at least 2.1 billion years ago, but multicellularity likely evolved in a number of lineages.

A

T.

50
Q

How can scientists determine that multicellular life arose more than once?

A

Animals are more closely related to single-celled eukaryotes than to fungi

51
Q

How can studying living bacteria offer clues to how multicellularity arose?

A

By studying biofilms, we can see how these single-celled organisms work together.

52
Q

Earliest Algae fossil?

A

1.6 byo

53
Q

Red Algae?

A

1.2 bya

54
Q

Green Algae?

A

750 mya

55
Q

When did the transition to multicellular life begin and did it evolve multiple times?

A

2.1 bya and yes.

56
Q

Oldest animal fossil? and what did it resemble?

A

650 mya resembling sponges.

57
Q

Why is the search for early animal fossils difficult and spark debate?

A

It is hard to distinguish between the ancient remains of a primitive animal from a colony of single-celled eukaryotes.

58
Q

Where and when did the ediacaran fauna exist?

A

Diverse and unique animals dominated the oceans from 575 – 535 mya

59
Q

T or F: Nearly all living animal lineages, including chordates, evolved during the Cambrian period.

A

True.

60
Q

Which fossils often took the form of disks, fronds, or blobs?

A

Ediacaran fauna.

61
Q

Did all the different organisms classified as Ediacaran fauna appear in the fossil record at the same time?

A

No. The fossil record indicates that some organisms appeared as early as 575 million years ago, but other organisms did not appear into 20 million years later.

62
Q

Why is a notochord an important adaptation for understanding the evolution of humans?

A

A notochord is a characteristic of chordates.

63
Q

What are the earliest signs of terrestrial life?

A

Prokaryotes colonized terrestrial environments first

– Fossils date to 2.6 bya

64
Q

First terrestrial plants?

A

Oldest terrestrial plant fossils are 475 myo
– Early plants resembled mosses and liverworts
• Large forest ecosystems within 100 million years

65
Q

Date of terrestrial fungi?

A

Fungi appear ~ 400 myo – Associated with plants

66
Q

First terrestrial animal life (invertebrates)?

A

Invertebrate trackways date to 480 mya
– Probably relatives of insects and spiders
– Not clear whether they lived on land permanently
• Oldest fossil of fully terrestrial animal dates to 428 mya

67
Q

First terrestrial animal life (vertebrates)?

A

Oldest trackways date to 390 mya

• Oldest fossils of tetrapods date to 370 mya

68
Q

What evidence supports the idea that fungi were important to the establishment of land plants?

A

Close association even in modern plants, found fossils of fungi intertwined with fossils of plants, oldest fossils of fungi are groups that provide nutrients to plants.

69
Q

Where did mammals come from?

A

Mammals evolved from synapsids

70
Q

When did vertebrates begin to dominate?

A

Dominant vertebrates around 280 myo

71
Q

When did the first mammals emerge?

A

First mammals emerged 150 mya

72
Q

Explain the diversification of mammals?

A

Mammals diversified after dinosaurs went extinct (~65 mya)

• Whales, bats, and primates all emerged around 50 mya

73
Q

What are the oldest human fossils?

A

Oldest human fossils are ~200,000 years old

74
Q

Evolution of birds:

A

~150 mya

– Descendants of dinosaurs

75
Q

Evolution of flowers:

A

~132 mya

– Grasses did not diversify until ~20 mya

76
Q

Evolution of insects:

A

~400 mya but most current lineages appear much later

77
Q

What allowed us to know synapsids were tetrapods?

A

they had four legs that they used to walk with.

78
Q

What group existed 350 mya: teleosts, tetrapods, birds

A

teleosts

79
Q

Which group does not apply to the idea that “many of the most diverse animal and plant species alive today belong to young lineages?
:Flowering plants, insects, birds, bony fish, mammals

A

insects

80
Q

What do geologists use to estimate the age of rocks?

A

the breakdown of radioactive isotopes.

81
Q

When to biomarkers of animals date back to?

A

650 million years

82
Q

How would you describe the fossil record?

A

a patchy, fragmented record that indicates that humans are relatively recent arrivals.

BIO 303 (4 decks)

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