Community Ecology

Community Ecology is topic 8.5 of AP Biology, inside Ecology. This page works through three real practice questions on it, with the full reasoning behind each credited answer.

33 questionsConcept Explanation85% with a figure
Worked examples

Three real community ecology questions

From the practice pool, not the mock papers — each with the reasoning that produces the answer.

85% of them come with a figure. Reading the graph or diagram correctly is most of the work here before any content knowledge applies.

Representing and Describing Data · with figure

Two protist species are grown separately and together in the same type of culture medium. Which interpretation is best supported?

  1. ASpecies A remains high while Species B is excluded in mixed culturecorrect
  2. BSpecies B grows best when Species A is present.
  3. CThe two species cannot use any overlapping resources because both persist equally together.
  4. DCompetition data cannot be interpreted unless both species are plants.
Why A is correct

Each species can reach high density alone, but Species B is near zero when grown with Species A. This supports that Species A outcompetes Species B under the shared culture conditions.

The evidence in the prompt matters before the topic label: "Two protist species are grown separately and together in the same type of culture medium. Which interpretation is...". The supported answer is "Species A appears to outcompete Species B under the shared culture conditions" because Each species can reach high density alone, but Species B is near zero when grown with Species A. Distractors such as Species B grows best when Species A is present or two species cannot use any overlapping resources because both... either ignore the stated pattern or name a related concept without matching the evidence.

Representing and Describing Data · with figure

Ecologists compare plants with and without a leaf parasite. Which interpretation is best supported? Use Figure 1 to answer the question.

  1. ALower host reproduction with parasite presence supports parasitismcorrect
  2. BParasitism means both organisms always benefit equally.
  3. CSeed production measures the parasite's chromosome number.
  4. DInfected plants produce more seeds than uninfected plants.
Why A is correct

Infected plants produce fewer seeds than uninfected plants. A relationship in which one organism benefits while the host is harmed is consistent with parasitism.

The evidence in the prompt matters before the topic label: "Ecologists compare plants with and without a leaf parasite. Which interpretation is best supported". The supported answer is "Parasite presence is associated with lower host seed production, consistent..." because A relationship in which one organism benefits while the host is harmed is consistent with parasitism. Distractors such as Parasitism means both organisms always benefit equally or Seed production measures the parasite's chromosome number either ignore the stated pattern or name a related concept without matching the evidence.

Concept Explanation · with figure

Two closely related bat species feed on similar insects in the same forest. Which interpretation is best supported by the activity data?

  1. AA lower Shannon index indicates greater diversity because one species dominates the sample.
  2. BTwo species use different prey resources
  3. CBoth species must feed at exactly the same time because they eat similar prey.
  4. DFeeding at different times can reduce overlapcorrect
Why D is correct

The two species use similar prey but at different peak feeding times. Temporal partitioning can reduce direct competition by separating resource use in time.

The evidence in the prompt matters before the topic label: "Two closely related bat species feed on similar insects in the same forest. Which interpretation is best supported...". The supported answer is "Different feeding times can reduce direct competition for similar prey" because The two species use similar prey but at different peak feeding times. Distractors such as lower Shannon index indicates greater diversity because one species... or two species use completely different prey resources either ignore the stated pattern or name a related concept without matching the evidence.

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Last reviewed 2026-08-28. Topic and unit names follow the College Board course framework. Question counts describe the PrepScore practice bank, not the exam.

Work community ecology until the reasoning is automatic.

Real AP questions with a full explanation on every answer, and a mistake bank that only clears when you get it right.