AP Biology: Disturbance, Succession, and Community Resilience Practice Questions
Practice ecological disturbance, succession, and community resilience with original AP Biology multiple-choice questions. These items connect recovery patterns to soil, propagules, species traits, experimental controls, and evidence from changing communities.
Free original practice questions for study purposes. Open Exam Prep is an independent study resource and is not affiliated with, endorsed by, or sponsored by the makers of AP Exams.
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Answer the questions below — you get instant feedback and a full explanation for each.
1. A lava flow cools into bare rock with no soil. Which process would begin community development at this site?
Explanation. Primary succession begins on a newly exposed surface where soil and an established biological community are absent. Early colonists can contribute organic matter and help soil develop.
2. A grassland burns, but its soil, buried seeds, and some underground stems survive. Which prediction is most reasonable?
Explanation. Because soil and biological legacies remain, the site undergoes secondary succession. Seeds, roots, microbes, and nearby colonists can speed recovery, although the exact former community may not return immediately.
3. Which observation best demonstrates ecological resistance rather than resilience?
Explanation. Resistance is the ability to remain relatively unchanged while a disturbance occurs. Resilience instead describes the degree or speed of recovery after change.
4. Two wetlands lose 60% of their plant biomass during the same storm. Wetland A returns to its previous biomass in one year, while Wetland B remains at 40% after four years. Which conclusion is best supported?
Explanation. Both wetlands changed by the same amount during the storm, so this evidence does not distinguish their resistance. Wetland A recovered faster, supporting greater resilience for the measured property, biomass.
5. Why do surviving seed banks often accelerate succession after a disturbance?
Explanation. A seed bank is a biological legacy that supplies propagules without requiring every plant species to disperse from elsewhere. It can speed recolonization but does not guarantee complete restoration of the former community.
6. An early-successional plant produces many small, wind-dispersed seeds and grows rapidly in full sunlight. How do these traits most directly help after a disturbance?
Explanation. High seed production, effective dispersal, and rapid growth help pioneer species reach and exploit open, resource-rich patches. Later environmental changes and competition can reduce their dominance.
7. Researchers compare forest stands that burned 2, 20, and 80 years ago to infer succession. What is the main limitation of this chronosequence approach?
Explanation. A chronosequence substitutes different sites for observations through time. If the sites differ in other ways, those differences can be mistaken for successional change.
8. Which design would best test whether repeated mowing changes plant community recovery after a severe drought?
Explanation. Replication, treatment and control plots, pre-disturbance data, and repeated recovery measurements help separate mowing effects from drought effects and normal variation among plots.
9. A short flood causes a sharp but temporary drop in insect abundance, whereas continuous nutrient runoff keeps algal biomass elevated for years. How should these disturbances be classified?
Explanation. A pulse disturbance is brief, even if its effects persist for a time. A press disturbance is sustained, as with continuing nutrient input that maintains altered conditions.
10. After a hurricane, one forest regains its former leaf area but is now dominated by different tree species. Which statement best describes the evidence?
Explanation. Recovery depends on the response variable. Leaf area indicates recovery of one structural or functional property, while the shift in dominant species shows incomplete compositional recovery.
11. Moderately disturbed stream patches contain more invertebrate species than patches disturbed either very rarely or very frequently. Which explanation is most consistent with this pattern?
Explanation. One possible mechanism is that intermediate disturbance creates opportunities for colonists while occurring slowly enough for multiple species to persist. The observed pattern supports this context-specific explanation, not a universal rule.
12. Which community would most likely recover quickly after a local disturbance that removes one pollinator species?
Explanation. Functional redundancy can support resilience because other species may partly compensate for the lost function. Recovery is less likely when a unique function or the habitat required for recolonization is permanently lost.
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FAQ
What is the difference between primary and secondary succession?
Primary succession begins where a developed soil and established community are absent. Secondary succession follows disturbance where soil or other biological legacies remain.
How are resistance and resilience different?
Resistance describes how little a measured property changes during disturbance. Resilience describes how well or how quickly that property recovers afterward.
Does succession always return a community to its exact previous state?
No. Recovery depends on disturbance severity, surviving organisms, dispersal, environmental conditions, and later interactions. Ecosystem functions may recover even when species composition changes.