Biology 100B Review #2 (Exam I)

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  1. What is the biological species concept?
    What are limitations to this concept?
    Name 3 other species definitions in addition to the biological species definition.
    • biological species concept
    • I. Species = population or group of populationswho can interbreed in nature to produceviable, fertileof spring; but do not produce viable, fertile offspringwith other populations

    • Limitations
    • -Prezygotic barriers
    • -Postzygotic barriers

    • Other Species Definitions
    • - Morphological species (“Linnaeus type”)

    - Paleontological species

    - Ecological species
  2. Describe prezygotic and postzygotic barriers that lead to reproductive isolation.
    • Prezygotic
    • -mechanical isolation (different sizes and shapes of reproductive organs)

    -temporal isolation (mating seasons)

    -behavior isolation (mating calls, colors and shapes)

    -gametic isolation (sperm not able to attach to egg)

    • Postzygotic barriers
    • - Low zygote viability
    • - Low adult viability
    • - Hybrid infertility
  3. Compare/contrast allopatric and sympatric speciation.
    What are the mechanisms for reproductive isolation with in each?
    Allopatric Speciation (other homeland)

    • - Geographic separation
    • - Gene flowinterrupted or reduced
    • - One or both populations may undergo evolutionary change

    Sympatric Speciation (together homeland)

    • - Not Geographically isolated
    • - Reproductively isolated
    • - Mechanisms of reproductive isolation

    • Mechanisms of reproductive isolation
    • - Disruptive selection: Ecological isolation due to habitat differentiation & sexual selection

    -Polyploidy: Extra sets of chromosomes, hybrid often sterile.
  4. What is adaptive radiation?
  5. Describe 3 outcomes of species overlap in hybrid zones over time
    1. Hybrid ZoneReinforcement: strengthening reproductive barriers

    2. Hybrid Zone Fusion: weakening reproductive barriers

    3. Hybrid Zone Stability:Continued Formation of Hybrid Individuals
  6. Where did life likely start?
    What were the raw materials necessary for it?
    What is the currently most accepted 4-step hypothesis for the origin of life?

    Explain each step. Is there any evidence to support this hypothesis?
    • - Water
    • - Methane, Ammonia, Hydrogen sulfide

    • 4-step hypothesis for the origin of life
    • 1. Synthesis of non--living organic molecules
    • 2. Joining of monomers to form polymers
    • 3. Packaging of polymers into protocells
    • 4. Origin of self--replicating molecules
  7. When did earth form?
    - Earth formed about 4..6 billion years ago
  8. How do sedimentary strata, index fossils, isotope dating and magnetism of rocks elucidate evolution in the fossil record?
    -Sedimentary strata reveal relative age of fossils

    - Absolute age of fossil—radiometric dating (isotope)

    - Magnetism of rock (reversal of poles)
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Biology 100B Review #2 (Exam I)
2013-10-02 22:47:16
ccsf bio100B examI

Review 2
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