Biology II Chapter 25

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Yasham
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Biology II Chapter 25
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2011-10-06 18:38:25
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Biology History Life Earth
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Chapter 25 of Campbell's Biology Textbook 8th - The History of Life on Earth
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  1. What is macroevolution?
    The pattern of evolution over large time scales.

    Specific examples of macroevolution include the origin of key biochemical processes such as photosynthesis, the emergence of the first terrestrial vertebrates, and the long-term impact of a mass extinction of the diversity of life.
  2. (T/F) Scientists hypothesize that chemical and physical processes on early Earth, aided by the emerging force of natural selection, could have produced very simple cells through a sequence in four main stages:
    a) The abiotic (nonliving) synthesis of small organic molecules, such as amino acids and nucleotides
    b) The joining of these small molecules into macromolecules, including proteins and nucleic acids
    c) The packaging of these molecules into "protobionts", dropletswith membranes that maintained an internal chemistry different from that of their surroundings
    d) The origin of self-replicating molecules that eventually made inheritance possible
    True.
  3. Scientists hypothesize that chemical and physical processes on early Earth, aided by the emerging force of natural selection, could have produced very simple cells through a sequence in four main stages:

    A) ______________________
    B) The joining of these small molecules into macromolecules, including proteins and nucleic acids
    C) The packaging of these molecules into "protobionts", droplets with membranes that maintained an internal chemistry different from that of
    their surroundings
    d) The origin of self-replicating molecules that eventually made inheritance possible
    A) The abiotic (nonliving) synthesis of small organic molecules, such as amino acids and nucleotides
    (this multiple choice question has been scrambled)
  4. Scientists hypothesize that chemical and physical processes on early Earth, aided by the emerging force of natural selection, could have produced very simple cells through a sequence in four main stages:

    A) The abiotic (nonliving) synthesis of small organic molecules, such as amino acids and nucleotides
    B) The packaging of these molecules into "protobionts", droplets with
    C) __________________
    membranes that maintained an internal chemistry different from that of their surroundings
    d) The origin of self-replicating molecules that eventually made inheritance possible
    C) The joining of these small molecules into macromolecules, including proteins and nucleic acids
    (this multiple choice question has been scrambled)
  5. Scientists hypothesize that chemical and physical processes on early Earth, aided by the emerging force of natural selection, could have produced very simple cells through a sequence in four main stages:

    A) The origin of self-replicating molecules that eventually made inheritance possible
    B) ____________________
    C) The abiotic (nonliving) synthesis of small organic molecules, such as amino acids and nucleotides
    D) The joining of these small molecules into macromolecules, including proteins and nucleic acids
    B) The packaging of these molecules into "protobionts", droplets with membranes that maintained an internal chemistry different from that of their surroundings
    (this multiple choice question has been scrambled)
  6. Scientists hypothesize that chemical and physical processes on early Earth, aided by the emerging force of natural selection, could have produced very simple cells through a sequence in four main stages:

    a) The abiotic (nonliving) synthesis of small organic molecules, such as amino acids and nucleotides
    b) The joining of these small molecules into macromolecules, including proteins and nucleic acids
    c) The packaging of these molecules into "protobionts", droplets with
    membranes that maintained an internal chemistry different from that of their surroundings
    d) ________________
    d) The origin of self-replicating molecules that eventually made inheritance possible
  7. In 1953, Miller and Urey created laboratory conditions comparable to the reducing environment of early Earth. Their apparatus yielded a variety of _________ found in organisms today, along with other organic compounds.

    What did the experiments demonstrate?
    amino acids

    These also demonstrated that abiotic (nonliving) synthesis of organic molecules is possible.
  8. (T/F) The presence of small organic molecules, such as amino acids, is not sufficient for the emergence of life as we know it.

    The joining of these small molecules into macromolecules, including proteins and nucleic acids. Amino acid polymers could have formed without the help of enzymes or ribosomes.
    True.

    Some researcher have been able to produce polymers of amino acids by dripping solutions of amino acids on hot sand, clay, or rock.
  9. What are protobionts?
    Collections of abiotically (nonliving) produced molecules surrounded by a membrane-like structure.

    Protobionts may exhibit some properties of life, including simple reproduction and metabolism, as well as the maintenance of an internal chemical environment different from that of their surroundings.
  10. (T/F) Two key properties of life are accurate replication and metabolism. Neither of which can exist without the other.

    DNA molecules carry genetic information, including the instructions needed to replicate themselves accurately. But the replication of DNA requires elaborate enzymatic machinery, along with a copious supply of nucleotide buidling blocks that must be provided by the cell's metabolism.
    True.
  11. (T/F) The first genetic material was most likely DNA, not RNA.
    False.

    The first genetic material was most likely RNA, not DNA. RNA, which plays a central role in protein synthesis, can also carry out a number of enzyme-like catalytic functions.
  12. What are ribozymes?
    An RNA molecule that functions as an enzyme, catalyzing reactions during RNA splicing.

    Some ribozymes can make complementary copies of short pieces of RNA, provided that they are supplied with nucleotide building blocks.

    It was believe that these allowed for self-replicating molecules.
  13. (T/F) The RNA molecules whose equence is best suited to the surrounding environment and has the greatest ability to replicate itself will leave the most descendant molecules.

    Its descendants will not be a single RNA "species" but instead willbe a family of sequences that differ slightly because of copying errors.

    Occasionally, a copying error will result in a molecule that folds into a shape that is even more stable or more adept at self-replication than the ancestral sequence.
    True.
  14. (T/F) A protobiont with self-replicating, catalytic RNA would differ from its many neighbors that carry RNA or that carried RNA without such capabilities.
    True.
  15. What hypothesis did Miller and Urey test in their famous experiment?
    The hypothesis that conditions on early Earth could have permitted the synthesis of organic molecules from inorganic ingredients.
  16. How would the appearance of protobionts have represented a key step in the origin of life?
    In contrast to random mingling of molecules in an open solution, segregation of molecular systems by membranes could concentrate organic molecules, assisting biochemical reactions.
  17. How are rocks and fossils dated?
    Radiometric dating, which is based on the decay of radioactive isotopes.

    A radioactive "parent" isotope decays to a "daughter" isotpe at a constant rate. The rate of decay is expressed by the half-life, the time required for 50% of the parent isotope to decay.
  18. What is the geologic record?
    The division of Earth's history into time periods, grouped into three eons - Archaean, Proterozoic, and Phanerozoic - and further subdivided into eras, periods, and epochs.
  19. The first two eons - Archaean and the Proterozoic - together lasted approxately

    a) 6 billion years.
    b) 5 billion years.
    c) 4 billion years.
    d) 3 billion years.
    C.
  20. What two are not of the three Eons?

    a) Paleozoid
    b) Archaean
    c) Proterozoic
    d) Mesozoic
    e) Phanerozoic
    A and D
  21. What is not one of the eras for the Phanerozoic eon?

    a) Paleozoid
    b) Cenozoic
    c) Proterozoic
    d) Mesozoic
    C.
  22. How long ago did the first evidence of first single-celled organisms appear in the fossil record? Where were they found? What type of cells were they?
    The earliest evidence of life, dating 3.5 billion years ago, comes from fossilized stromatolites.

    Stromatolites are layered rocks that form when certain prokaryotes bind thin films of sediment together.
  23. (T/F) Most atmospheric oxygen gas is of biological origin, produced during the water-splitting step of photosynthesis.
    True.

    When oxygenic photosynthesis first evolved, the free O2 it produced probably dissolved in the surrounding water until it reached a high enough concentration to react with dissolved iron.

    Additional O2 dissolved in the water until the seas and lakes became saturated with O2, after this occurred, O2 finally began to "gas out" of the water and enter the atmosphere.
  24. What is the oxygen revolution? What impact did this have on life?
    A moment in time when O2 in the atmosphere, about 2.7 to 2.2 billion years ago, shot up relatively rapidly to more than 10% of its present level. It should be noted that the amount of O2 in the atmosphere was increasing gradually prior to this.

    Oxygen in certain chemical forms, oxygen attacks chemical bonds and can inhibit enzymes and damage cells.

    As a result the rising concentration of atmospheric O2 probably doomed many prokaryotic groups.
  25. What most likely brought about the early gradual rise in atmospheric O2 levels?
    ancient cyanobacteria.
  26. The oldest widely accepted fossils of eukaryotes are about

    a) 1.9 billion years ago.
    b) 2.0 billion years ago.
    c) 2.1 billion years ago.
    c) 2.1 million years ago.
    d) 3.1 million years ago.
    C
  27. (T/F) Eukaryotic cells have a nuclear envelope, mitochondria, endoplasmic reticulum, and other internal structures that prokaryotes lack.
    True.
  28. (T/F) Prokaryotes and eukaryotes both have a cyctoskeleton, a feature that enables both cells to change their shape and thereby surround and engulf other cells.
    False.

    Only eukaryotic cells have a cytoskeleton.
  29. What does the endosymbiosis model support?
    Endosymbiosis is a process in which a unicellular organism (the "host") engulfs another cell, which lives within the host cell and ultimately becomes an organelle in the host cell; also refers to the hypothesis that mitochondria and plastids were formerly small prokaryotes that began living within larger cells.

    This supports that mitochondria and plastids (a general term for chloroplasts and related organelles) were formerly small prokaryotes that begin living within larger cells.
  30. The term endosymbiont refers to a cell that lives within another cell, called the host cell. What does this model state about the origin of eukaryotes?
    The proposed ancestors of mitochondria were aerobic, heterotrophy prokaryotes (meaning they used oxygen to metabolize organic molecules obtained from other organism) and found their way into a large prokaryote that gained enetry to the host cell as undigested prey or internal paraistes.

    These evenutally came to have a mutally beneficial relationship with the host and the parts became inseparable, forming a single organism.
  31. What does the model of serial endosymbiosis suppose concerning mitochondria and plastids?
    The model supposes that mitochondria evolved before plastids through a sequence of endosymbiotic events as all eukaryotes have mitochondria but not all have plastids.
  32. Based on comparisons of DNA sequences, the first multicellular eukaryotes were believed to have lived

    a) 1.4 billion years ago.
    b) 1.5 billion years ago.
    c) 1.6 billion years ago.
    d) 1.7 billion years ago.
    B.
  33. The oldest known fossils of multicellular eukaryotes are relatively small algae that lived about

    a) 1.5 billion years ago.
    b) 1.4 billion years ago.
    c) 1.3 billion years ago.
    d) 1.2 billion years ago.
    D
  34. Why were multicellular eukaryotes limited in size and diversity until the late Proterozoic?
    The "snowball Earth" hypothesis suggests that most life would have been confined to areas near deep-sea vents and hot springs; the appearance of multicellular eukaryotes corresponds roughly to the time when snowball Earth thawed (beginning about 565 million years ago).
  35. What was the Cambrian explosion?
    The period early in the Cambrian period (535 - 525 million years ago) when many phyla of living animals appear suddenly.

    • Fossils of three living animal phyla appear suddenly:
    • Cnidaria (sea anemones and their relatives)
    • Porifera (sponges)
    • Mollusca (molluscs)

    Prior to the Cambrian explosion, all large animals were soft-bodied with little evidence of predation.

    In a short period of time (10 years), predators over 1m in lengths emerged that had claws and other features for capturing prey; simultaneously, new defensive adaptations, such as sharp spines and heavy body armor appears in their prey.
  36. What was this period called?

    In a short period of time (10 years), predators over 1m in lengths emerged that had claws and other features for capturing prey; simultaneously, new defensive adaptations, such as sharp spines and heavy body armor appears in their prey.
    The Cambrian explosion (535 -525 million years ago)
  37. Some believe that the Cambrian explosion had a long fuse. What did this refer to?
    This refers that there are periods in the fossil record where there are a lack of fossils.
  38. How long ago did the colonization of land most likely occur?
    500 million years ago.
  39. The first appearance of free oxygen in the atmosphere likely triggered a massive wave of extinctions among the prokaryotes of the time. Why?
    Free oxygen attacks chemical bonds and can inhibit enzymes and damage cells.
  40. What evidence supports the hypothesis that mitochondria preceded plastids in the evolution of eukaryotic cells?
    All eukaryotes have mitochondria or remnants of these organelles, but not all eukaryotes have plastids.
  41. What is continental drift?
    The slow movement of the continental plates across Earth's surface.
  42. What is Pangaea? How long ago did Pangaea exist? What would've caused by this?
    The supercontinent that formed near the end of the Paleozoic era, when plate movements brought all the land-masses of Earth together.

    Pangaea existed approximately 251 million years ago.

    Allopatric speciation.
  43. What is a "mass extinction"?
    Period of time when global environmental changes lead to the elimination of a large number of species throughout Earth.
  44. (T/F) The origin of one species can spell doom for another.
    True.
  45. How many mass extinctions have their been in the past 500 million years? In each of the mass extinctions, more than what percentage of animals became extinct?
    Five mass extinctions. More than 50% of marine life disappeared.
  46. What two mass extinctions have received the most attention?
    The Permian and the Cretaceous
  47. What caused the Permian mass extinction? How long ago did this occur? What eras did the mass extinction define? How many species disappeared?
    The Permian mass extinction, defines the boundary between the Paleozoic and Mesozoic eras (251 million years ago) and lasted approximately 5 million years.

    This claimed about 96% of marine animal species and drastically altered life in the ocean.

    The cause of the Permian mass extinction was believed to be the volcanic eruptions in Siberia where enough carbon dioxide was produced to warm the global climate by an estimated 6C.

    The reduced temperature difference between the equator and the poles would have slowed the mixing of ocean water, which in turn would have reduced the amount of oxygen available to marine organisms. This oxygen deficit may have been a major cause of the Permian extinction of marine life.
  48. What caused the Cretaceous mass extinction? How long ago did this occur? What eras did the mass extinction define? How many species disappeared?
    The Cretaceous mass extinction occurred about 65.5 million years ago and marks the boundary between the Mesozoic and Cenozoic eras.

    This extinguished more than half of all marine species and eliminated many families of terrestrial plants and animals, including most of the dinosaurs.

    Iridium is an element very rare on Earth but it common in many meteorites. It is believed that a huge cloud of debris billowed into the atmosphere when an asteroid or large comet collided with Earth. The cloud would have blocked sunlight and severely disturbed the global climate for several months.
  49. What are adaptive radiations?
    Periods of evolutionary change in which groups of organisms form many new species whose adaptations allow them to fill different ecological roles, niches, in their communities.

    Large-scale adaptive radiations occurred after each of the big five extinctions, when survivors became adapted to the many vacant ecological niches.
  50. Explain consequences of continental drift for life on Earth?
    Continental drift alters the physical geography and climate of Earth, as well as the extent to which organisms are geographically isolated. Because these factors after extinction and speciation rates, continental drift has a major impact on life on Earth.
  51. What factors promote adaptive radiations?
    Mass extinctions; major evolutionary innovations; the diversification of another group of organisms (which can provide new sources of food); migration to new locations where few competitor species exist.
  52. What is heterochrony?
    • (hetero - different)
    • (chronos - time)
    • An evolutionary change in the rate or timing of an organism's development.

    For example, an organism's shape dependsin part on the relative growth rates of different body parts during development.
  53. What is the condition known as paedomorphosis?
    • (paedos - child)
    • (morphosis - formation)
    • The retention in an adult organism of the juvenile features of its evolutionary ancestors.
  54. What are homeotic genes?
    Master reulatory genes that determine such basic features as where a pair of wings and a pair of legs will develop on a bird or how a plant's flower parts are arranged.

    For example, the Hox gene provides positional information in an animal embryo.
  55. How can heterochrony cause the evolution of different body forms?
    Heterochrony can cause a variety of morphological changes. For example, if the onset of sexual maturity changes, a retention of juvenile characteristics (paedomorphosis) may result. Paedomorphosis can be caused by small genetic changes that result in large changes in morphology, as seen in the axolotl salamander.
  56. Why is it likely that Hox genes have played a major role in the evolution of novel morphological forms?
    In animal embryos, Hox genes influence the development of structures such as limbs or feeding appendages. As a result, changes in these genes - or in the regulation of these genes - are likely to have major effects on morphology.
  57. (T/F) Evolution is not goal oriented. It can predict what will be necessary in the future.
    True.
  58. How can the Darwinian concept of descent with modification explain the evolution of such complex structures as the vertebrate eye?
    Compex structures do not evolve all at once, but in increments, with natural selection selecting for adaptive variants of the earlier versions.
  59. (T/F) Developmental genes affect morphological differences between species by influencing the rate, time and spatial patterns of change in an organism's form as it develops into an adult.
    True.
  60. (T/F) The evolution of new morphological forms can be caused by changes in the nucleotide sequences or regulation of developmental genes.
    True.
  61. (T/F) Novel and complex biological structures can evolve through a series of incremental modifications, each of which benefits the organism that possesses it.
    True.
  62. (T/F) Evolutionary trends can be caused by factors such as natural selection in a changing environment or species selection. Like all aspects from interactions, between organisms and their current environments.
    True.
  63. Fossilized stromatolites

    a) all date from 2.7 billion years ago.
    b) formed around deep-sea vents.
    c) resemble structures formed by bacterial communities that are found today in some warm, shallow, salty bays.
    d) provide evidence that plants moved onto land in the company of fungi around 500 million years ago.
    e) contain the first undisputed fossils of eukaryotes and date from 2.1 billion years ago.
    C
  64. The oxygen revolution changed Earth's environment dramatically. Which of the following adaptations took advantage of the presence of free oxygen in the oceans and atmosphere?

    a) the evolution of cellular respiration, which used oxygen to help havest energy from organic molecules.
    b) the persistence of some animal groups in anaerobic habitats
    c) the evolution of photosynthetic pigments that protected early algae from the corrosive effects of oxygen
    d) the evolution of chloroplasts after early protists incorporated photosynthetic cyanobacteria
    e) the evolution of multicellular eukaryotic colonies from communities of prokaryotes
    A
  65. Select the factor most likely to have caused the animals and plants of India to differ greatly from species in nearby Southeast Asia

    a) The species have become separated by convergent evolution.
    b) The climates of the two regions are similar.
    c) India is in the process of separating from the rest of Asia.
    d) Life in India was wiped out by ancient volcanic eruptions.
    e) India was a separate continent until 55 million years ago.
    E
  66. Adaptive radiations can be a direct consequence of four of the following for factors. Select the exception.

    a) vacant ecological niches
    b) genetic drift
    c) colonization of an isolated region that contains suitable habitat and few competitor species
    d) evolutionary innovation
    e) an adaptive radiation in a group of organisms (such as plants) that another group uses as food
    B
  67. 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) the influence of environment on development.
    b) paedomorphosis
    c) a change in a developmental gene or in its regulation that altered the spatial organization of body parts.
    d) heterochrony
    e) gene duplication
    C
  68. Which of the following steps has not yet been accomplished by scientists studying the origin of life?

    a) synthesis of small RNA polymers by ribozymes
    b) abiotic synthesis of polypeptides
    c) formation of molecular aggregates with selectively permeable membranes
    d) formation of protobionts that use DNA to direct the polymerizationof amino acids
    e) abiotic synthesis of organic molecules.
    D
  69. A swim bladder is a gas-filled sac that helps fish maintain buoyancy. The evolution of the swim bladder from lungs of an ancestral fish is an example of

    a) an evolutionary trend.
    b) exaptation
    c) changes in Hox gene expression
    d) paedomorphosis
    e) adaptive radiation
    B
  70. What is an exaptation?
    Structures that evolve in one context but become co-opted for another function. These are dintinguished from the adaptive origin of the original structure.

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