AP Biology: Plant-Pollinator Network Stability Practice Questions
Practice ecological network reasoning with original AP Biology multiple-choice questions. These items connect species interactions to community stability while distinguishing visitation from effective pollination and correlation from causal evidence.
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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1. In a diagram of a plant-pollinator network, circles represent species and lines connect a pollinator to each plant species it visits. What does one line most directly represent?
Explanation. A line, or edge, records an interaction between two species represented as nodes. Its presence does not by itself show genetic similarity, population size, pollination effectiveness, or shared evolutionary history.
2. A meadow contains several bee and fly species that pollinate the same abundant plant. If one pollinator declines, the other species continue transferring enough pollen for similar seed production. Which feature most directly contributed to this response?
Explanation. Functional redundancy occurs when multiple species perform similar ecological roles. Overlap does not make the species identical, but it can buffer plant reproduction when the loss of one pollinator is compensated by others.
3. In a nested plant-pollinator network, specialist pollinators usually interact with which set of plants?
Explanation. Nestedness means that interactions of specialists tend to fall within the broader interaction sets of generalists. This describes network organization; it does not guarantee that the network will remain stable under every disturbance.
4. Researchers count 200 visits by two insect species to flowers. Species A makes 150 visits but rarely contacts anthers or stigmas; species B makes 50 visits and deposits many compatible pollen grains. Which conclusion is best supported?
Explanation. Frequent flower visits do not necessarily transfer pollen. Estimating contribution to plant reproduction requires combining visit rate with evidence such as pollen deposition or resulting seed production.
5. A late frost delays flowering by three weeks, but the peak activity of a plant's main pollinator does not shift. Which direct effect is most likely?
Explanation. Different responses to temperature can create a phenological mismatch, reducing the time when open flowers and active pollinators overlap. The reproductive effect depends on whether other effective pollinators or flowering periods compensate.
6. After a common bee species disappears, several plants receive visits from a fly species that those plants rarely interacted with before. What network process does this observation illustrate?
Explanation. Interaction rewiring occurs when surviving species form or strengthen different links after community change. Rewiring can provide compensation, but researchers must measure pollination effectiveness before concluding that plant reproduction is fully restored.
7. A network contains one dense group of alpine plants and pollinators and another dense group of lowland species, with few interactions between the groups. Which term best describes this structure?
Explanation. A modular network has clusters with many within-cluster interactions and relatively few links between clusters. Modules may limit how some disturbances spread, although the result depends on which species and links are affected.
8. A highly connected generalist pollinator is removed from a network model, and many specialist plants lose their only remaining visitor. What is the most cautious interpretation?
Explanation. A removal model identifies potential dependence and secondary losses in recorded links. It generates a hypothesis about vulnerability, while field measures of effective pollen transfer, seed production, and population trends are needed for stronger ecological conclusions.
9. Which experiment would best test whether greater pollinator diversity stabilizes plant seed production across variable weather?
Explanation. Replication and assignment of diversity treatments help separate diversity from other site differences. Repeated environmental conditions and a plant fitness response allow researchers to test stability as variation in function, not merely species count.
10. Two grasslands differ in plant-pollinator connectance, defined as the fraction of possible species interactions that are observed. What additional information is most important before concluding that the grassland with higher connectance is more stable?
Explanation. Connectance summarizes how many possible links are present, but stability can also depend on link strength, partner identity, functional effectiveness, and the disturbance considered. A single network metric is not sufficient evidence of general stability.
11. A restoration team wants to support a pollinator community whose species emerge at different times from spring through autumn. Which planting strategy best matches that goal?
Explanation. A sequence of overlapping bloom periods can supply resources to pollinators active at different times. Using diverse native plants and compatible flower traits can also support multiple interaction partners rather than one brief resource pulse.
12. Across 20 sites, plant-pollinator networks with more species also show less year-to-year variation in total seed production. Why does this result alone not prove that species richness caused stability?
Explanation. The association is consistent with a diversity-stability hypothesis, but unmeasured site differences could create the same pattern. Experiments, longitudinal changes, or strong controls for alternative variables would improve causal inference.
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FAQ
What is a plant-pollinator network?
It is a representation of plant and pollinator species as nodes connected by observed interactions such as flower visits. Additional measurements are needed to determine the strength and pollination effectiveness of each link.
Does a more connected pollination network always have greater stability?
No. Connectance can influence responses to disturbance, but stability also depends on species identities, interaction strengths, redundancy, rewiring, disturbance type, and the ecological function being measured.
How can scientists test whether a network is stable?
They can track interaction structure and ecological functions through time or manipulate species and environmental conditions in replicated experiments, then measure resistance, recovery, or variability.