Biology II exam 1

Last update by mayurcooled on 04/23/2014
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Antibiotic resistance in bacteria is an example of which of the following?

stabilizing selection

macroevolution

directional selection

disruptive selection

Hardy-Weinberg equilibrium

Answer:
directional selection

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    A population of squirrels is preyed on by small hawks. The smaller squirrels can escape into burrows. The larger squirrels can fight off the hawks. After several generations, the squirrels in the area tend to be very small or very large. What process is responsible for this outcome?

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    stabilizing selection

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    Stabilizing selection _____.

    occurs when some individuals migrate to an area with different environmental conditions

    prevents mutations from occurring

    occurs only in plants

    usually results in two distinct phenotypes

    favors intermediate variants in a population

    favors intermediate variants in a population
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    Birds with average-size wings survived a severe storm more successfully than other birds in the same population with longer or shorter wings. If severe storms occur regularly, then over time, one should expect these storms to bring about _____.

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    stabilizing selection
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    Tay-Sachs disease, which is lethal, results from having the homozygous recessive condition of the responsible gene. Which of the following statements is true?

    Homozygous dominant individuals will be more likely to reproduce than heterozygous individuals.

    Only homozygous dominant individuals will be able to survive and reproduce.

    Because homozygous recessive individuals die, the recessive allele will eventually be lost from the population.

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    Which type of selection maintains stable frequencies of two or more phenotypic forms in a population?

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    balancing selection

    neutral variation

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    stabilizing selection

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    Which of the following would seem to be an example of neutral variation?

    homozygosity of the cheetah population

    moth coloration

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    What is the importance of neutral variation in evolution?

    Neutral variation is usually removed from the population by natural selection because it does not confer an advantage in the current environment.

    Many mutations are silent and do not affect the amino acid that is coded for.

    DNA forensics relies on neutral variation among humans.

    Neutral variation increases genetic variation, allowing a population to carry more alleles that may help it respond to environmental change.

    Relative frequencies of neutral variations are controlled by natural selection.

    Neutral variation increases genetic variation, allowing a population to carry more alleles that may help it respond to environmental change.
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    Selection that acts over evolutionary time to preserve traits that increase an individual's ability to mate is known as _____.

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    Which statement below is true about sexual selection?

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    Sexual selection can result in sexual dimorphism—marked differences between the sexes in secondary sexual characteristics that are not associated directly with reproduction.

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    There is no evidence that intrasexual selection takes place between females.

    Intrasexual selection leads to the death of most unfit males in combat.

    Sexual selection can result in sexual dimorphism—marked differences between the sexes in secondary sexual characteristics that are not associated directly with reproduction
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    How does natural selection fashion organisms?

    Chance and the environment interact with natural selection, so that the best available traits are selected for.

    Sexual selection acts to make organisms better adapted to their environments.

    Neutral traits are often selected for because they will eventually produce alleles that confer an advantage.

    The best traits for the current environment arise in the population and are selected for.

    Brand new body plans arise often, giving natural selection many new possibilities to work with.

    Chance and the environment interact with natural selection, so that the best available traits are selected for.