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BIO 160 > 25. The history of life on earth > Flashcards

25. The history of life on earth Flashcards

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Biology 101 flashcards
1
Q

Key concept: Conditions on early Earth made the origin of life possible

A
  1. The abiotic (nonliving) synthesis of small organic molecules, such as amino acids and nitrogenous bases
  2. The joining of these small molecules into macromolecules such as proteins and nucleic acids
  3. The packaging of these molecules into protocells, droplets with membranes that maintained internal chemistry different from that of their surroundings
  4. The origin of self- replicating molecules that eventually made inheritance possible
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2
Q

Key concept: The fossil record documents the history of life

A

Fossils as a form of scientific evidence

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3
Q

Key concept: Key events in life’s history include the origins of unicellular and multicellular organisms and the colonization of land

A

Phanerozoic eon: Paleozoic, Mesozoic and Cenozoic era

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4
Q

Key concept: The rise and fall of groups of organisms reflect differences in speciation and extinction rates

A
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5
Q

Key concept: Major changes in body form can result from changes in the sequences and regulation of developmental genes

A
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6
Q

Key concept: Evolution is not goal oriented

A
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7
Q

How has life on earth changed over time

A

Continental drift, mass extinction, adaptive radiation

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8
Q

macroevolution

A
  • evolutionary change above the species level
    -the origin of a new group of organisms through a series of speciation events and the impact of mass extinctions on the diversity of life and its subsequent recovery
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9
Q

hydrothermal vents

A
  • the hypothesis that organic compounds were first produced in deep-sea hydrothermal vents
  • area on the seafloor where heated water and minerals from Earth’s interior gush into the seawater, producing a dark hot, oxygen-deficient environment
  • producers in a hydrothermal vent community are chemoautotrophic prokaryotes
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10
Q

alkaline vent

A
  • deep-sea hydrothermal vent that releases water that is warm rather than hot and that has a high pH (is basic)
  • these vents consist of tiny pores lined with iron and other catalytic minerals that some scientists hypothesize might have been the location of the earliest abiotic synthesis or organic compounds
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11
Q

ribozyme

A
  • an RNA molecule that functions as an enzyme, such as an intron that catalyzes its own removal during RNA splicing
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12
Q

Sedimentary rock

A
  • most fossils are found in sedimentary rock such as this plant fossil
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13
Q

radiometric dating

A
  • a method for determining the absolute age of rocks and fossils based on the half-life of radioactive isotopes
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14
Q

half-life

A
  • the amount of time it takes 50% of a sample of radioactive isotope to decay
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15
Q

stromatolites

A
  • layered rock that results from activities of prokaryotes that bind thin films of sediment together
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16
Q

endosymbiosis

A
  • a relationship between two species in which one organism lives inside the cell or cells of another organism
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17
Q

endosymbiont

A

-a cell that lives within another cell, called the host cell.

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18
Q

serial endosymbiosis

A
  • a hypothesis for the origin of eukaryotes consisting of a sequence of endosymbiotic events in which mitochondria, chloroplasts and perhaps other cellular structures were derived from small prokaryotes that had been engulfed by larger cells
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19
Q

Cambrian explosion

A
  • a relatively brief time in geologic history when many present-day phyla of animals first appeared in the fossil record. This burst of evolutionary change occurred 535-525 million years ago and saw the emergence of the first large, hard-boiled animals
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20
Q

plate tectonics

A
  • the theory that the continents are part of great plates of Earth’s crust that float on the hot underlying portion of the mantle. Movements in the mantle cause the continents to move slowly over time
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21
Q

Pangea

A
  • the supercontinent that formed near the end of the Paleozoic era, when plate movements brought all the landmasses of Earth together
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22
Q

mass extinction

A

the elimination of a large number of species throughout Earth, the result of global environmental changes

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23
Q

adaptive radiation

A

period of evolutionary change in which groups of organisms form many new species whose adaptations allow them to fill different ecological roles in their communities

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24
Q

heterochrony

A
  • evolutionary change in the timing or rate of an organisms development
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25
Q

paedomorphosis

A

the retention in an adult organism of the juvenile features of its evolutionary ancestors

26
Q

homeotic genes

A
  • any of the master regulatory genes that control the placement and spatial organization of body parts in animals, plants and fungi by controlling the developmental fate of groups of cells
27
Q

protocells

A

membrane-bounded droplets that have the same properties of cells

28
Q

Concept 25.1 summary

A
  • Experiments simulating possible early atmospheres have produced organic molecules from inorganic precursors. Amino acids, lipids, sugars, and nitrogenous bases have also been found in meteorites.
    Amino acids and RNA nucleotides polymerize when
  • Amino acids and RNA nucleotides polymerize when dripped onto hot sand, clay, or rock. Organic compounds can spontaneously assemble into protocells, membrane-bounded droplets that have some properties of cells.
    -The first genetic material may have self-replicating, catalytic RNA. Early protocells containing such RNA would have increased through natural selection.
29
Q

Concept 25.2 summary

A
  • The fossil record, based largely on fossils found in sedimentary rocks, documents the rise and fall of different groups of organisms over time.
    -Sedimentary strata reveal the relative ages of fossils. The ages of fossils can be estimated by radiometric dating and other methods.
    -The fossil record shows how new groups of organisms can arise via the gradual modification of preexisting organisms.
30
Q

Concept 25.4 Summary

A

-In plate tectonics, continental plates move gradually over time, altering the physical geography and climate of Earth, leading to extinctions in some groups and speciation in others.
-Evolutionary history has been punctuated by five mass extinctions that radically altered life’s history. Possible causes for these extinctions include continental drift, volcanic activity, and impacts from asteroids.
-Large increases in the diversity of life have resulted from adaptive radiations that followed mass extinctions. Adaptive radiations have also occurred in groups of organisms that possessed major evolutionary innovations or that colonized new regions in which there was little competition from other organisms.

31
Q

Concept 25.5 Summary

A

-Developmental genes affect morphological differences between species by influencing the rate, timing, and spatial patterns of change in an organism’s form as it develops into an adult.
-The evolution of new forms can be caused by changes in the nucleotide sequences or regulation of developmental genes.

32
Q

Concept 25.6 Summary

A

-Novel and complex biological structures can evolve through a series of incremental modifications, each of which benefits the organism that possesses it.
-Evolutionary trends can be caused by natural selection in a changing environment or species selection, resulting from interactions between organisms and their current environments.

33
Q

What evidence supports the hypothesis that mitochondria and plastids evolved from prokaryotic endosymbionts?

A

They have a single circular chromosome similar to bacterial chromosomes; their ribosomes are more like prokaryotic ribosomes than eukaryotic ribosomes

34
Q

The Miller and Urey abiotic synthesis experiment (and subsequent, similar experiments) showed that

A

simple organic molecules can form spontaneously under conditions like those thought to prevail early in Earth’s history

35
Q

What evidence most strongly suggests that an impact by an asteroid or meteorite may have caused the extinction of the dinosaurs?

A

Sedimentary rocks contain a layer of iridium, a mineral uncommon on Earth.

36
Q

Fossilized stromatolites

A

resemble structures formed by bacterial communities that are found today in some warm, shallow, salty bays

37
Q

The early atmosphere may not have been as reducing as originally postulated by Haldane, Oparin, Miller, and Urey. In light of current thinking about the composition of the early atmosphere, what is regarded as a likely place for the abiotic synthesis of organic molecules to have occurred?

A

Near volcanoes

38
Q

In the species selection model, __________ is to macroevolution as __________ is to microevolution.

A

differential speciation success; differential reproductive success

39
Q

Although they originated around 180 million years ago, mammals underwent an adaptive radiation starting approximately 65 million years ago. Why?

A

Between 180 and 65 million years ago, mammals were outcompeted by the well-established dinosaurs.

40
Q

Single-celled prokaryotes had the Earth to themselves for approximately __________.

A

1.5 billion years

41
Q

Adaptive radiations can be a direct consequence of four of the following five factors. Select the exception.

A

Genetic drift

42
Q

Which of the following would not have been a consequence of tectonic plate movements bringing previously separated landmasses together in the formation of the supercontinent of Pangaea about 250 million years ago?

A

Allopatric speciation increased.

43
Q

Retention of juvenile body features into sexual maturity is referred to as the presence of __________.

A

paedomorphosis

44
Q

Which of the following is not a unique anatomical feature of mammals that can be recognized in the fossil record?

A

Temporal fenestra

45
Q

If the wings of extant flying birds originally arose as thermoregulatory devices in ancestral reptiles, then the bird wings could be accurately described as __________.

A

exaptations

46
Q

What were the two major “problems” that had to be solved before plants, animals, and fungi could move into terrestrial habitats?

A

Reproduction and prevention of dehydration

47
Q

A genetic change that caused a certain Hox gene to be expressed along the tip of a vertebrate limb bud instead of farther back helped make possible the evolution of the tetrapod limb.

This type of change is illustrative of __________.

A

a change in a developmental gene or in its regulation that altered the spatial organization of body parts

48
Q

What was one ecological change that occurred following the Permian mass extinction?

A

The percentage of marine predators increased.

49
Q

The original atmosphere of Earth had little oxygen. What was the likely first source of oxygen that led to an oxygen atmosphere?

A

Cyanobacteria

50
Q

The correct order of the geologic eras, from most ancient to most recent, is __________.

A

Paleozoic, Mesozoic, and Cenozoic

51
Q

Macroevolution differs from microevolution in that macroevolution __________.

A

includes broad evolutionary changes above the species level

52
Q

Why is RNA, rather than DNA, thought to have been the first genetic material?

A

RNA can also function as a catalyst.

53
Q

Which of the following is a true statement about the current status of Earth’s biodiversity?

A

The current rate of extinctions is as high as 1,000 times the typical rate seen in the fossil record.

54
Q

Which of the following is the correct ordering of divisions of the geologic record from largest to smallest?

A

eon, era, period, epoch

55
Q

The amphibians, reptiles, and mammals comprise which group?

A

tetrapods

56
Q

The ratio of carbon-14 to carbon-12 in a fossil can be used to determine the age of the fossil because __________

A

carbon-14, unlike carbon-12, decays at a continuous rate after the death of an organism

57
Q

Why is the four-stage hypothesis for the abiotic origin of life useful?

A

It leads to predictions that can be tested.

58
Q

The fossil record is __________.

A

biased in favor of species that existed for a long time

59
Q

Which of the following is an internal structure that appears in eukaryotic cells and is also present in more ancient prokaryotic cells?

A

Vesicles

60
Q

Which of the following is a true statement concerning the history of Earth’s biological diversity?

A

The majority of species that ever lived are now extinct.

61
Q

Prior to the Cambrian explosion, all large animals had what characteristic in common?

A

They were all soft-bodied.

62
Q

You are watching a movie in which one of the characters excitedly claims to have found human remains in Asia dated at 10 million years old. The date was obtained by carbon-14 dating.

What is your reaction?

A

This can’t possibly be true because carbon-14 dating can only be used back to about 75,000 years.

BIO 160 (4 decks)

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