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Biology Ecology & Evolutionary Processes Flashcards

7 cards from real CLEP practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

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  1. Which type of selection favors individuals at both extremes of a phenotypic trait and eliminates intermediate phenotypes?

    Answer: Disruptive selection

    Disruptive (diversifying) selection favors phenotypic extremes over intermediate forms, potentially splitting a population into two distinct groups.

  2. A keystone species is best described as a species that:

    Answer: Has a disproportionately large effect on its ecosystem relative to its biomass

    A keystone species has an outsized ecological impact — its removal causes dramatic changes in community structure, far greater than expected from its numbers alone.

  3. Which reproductive isolating mechanism prevents two species from mating because they breed at different times of year?

    Answer: Temporal isolation

    Temporal isolation is a prezygotic barrier where species breed at different times (seasons, times of day), preventing interbreeding even if they share the same habitat.

  4. The r-selected reproductive strategy is characterized by:

    Answer: Many offspring with little parental investment

    r-selected species (r-strategists) produce large numbers of offspring with minimal parental care, maximizing reproductive rate rather than offspring survival.

  5. Carbon is returned from the biotic community to the atmosphere primarily through:

    Answer: Cellular respiration and decomposition

    Cellular respiration by all organisms and decomposition by decomposers release CO₂ back into the atmosphere, completing the carbon cycle.

  6. Which type of population growth occurs when resources are unlimited and the population increases at a constant per-capita rate?

    Answer: Exponential growth

    Exponential (geometric) growth produces a J-shaped curve and occurs when birth rates exceed death rates with no resource limitations.

  7. Homologous structures in different species provide evidence for evolution because they suggest:

    Answer: Descent from a common ancestor

    Homologous structures share anatomical origin from a common ancestor, indicating shared evolutionary history even if the structures now serve different functions.