AP Biology: Seed-Dispersal Network Stability Practice Questions
Practice ecological network reasoning with original AP Biology multiple-choice questions. These items connect fruiting plants, animal dispersers, seed movement, and recruitment while distinguishing observed interactions from effective dispersal 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.
advertisement
Answer the questions below — you get instant feedback and a full explanation for each.
1. In a seed-dispersal network, a line connects a fruiting plant species to a bird species. What does the line most directly indicate?
Explanation. A network edge represents a recorded interaction, such as fruit consumption or seed transport. Additional evidence is needed to determine where seeds were deposited, whether they germinated, and whether seedlings survived.
2. Three bird species disperse seeds of the same shrub to similar suitable sites. After one bird species declines, the other two carry enough seeds that shrub recruitment changes little. Which network feature best explains this response?
Explanation. Functional redundancy occurs when multiple species provide similar ecological functions. It can buffer seed dispersal after one species declines, although redundancy depends on dispersal distance, destination, season, and seed treatment as well as interaction overlap.
3. A small bird and a large mammal both eat the fruits of a tree. The bird drops most seeds beneath the parent crown, while the mammal deposits intact seeds hundreds of meters away in suitable habitat. Which measurement best distinguishes their contributions to effective dispersal?
Explanation. Effective seed dispersal depends not only on fruit removal but also on the quantity of seeds moved, the quality of deposition sites, and subsequent establishment. Tracking deposited seeds through germination or recruitment measures these differences directly.
4. A highly connected generalist mammal disappears from a network model, causing many plant species to lose recorded dispersal links. What is the most cautious conclusion?
Explanation. The model identifies potential dependence and motivates a hypothesis about vulnerability. Actual outcomes depend on interaction rewiring, disperser effectiveness, seed banks, habitat suitability, and plant demography, which require field measurements.
5. A highway divides a forest and prevents large ground-dwelling mammals from crossing, while small birds still move between fragments. Which immediate network change is most likely for large-fruited plants dispersed mainly by those mammals?
Explanation. Restricting movement of major dispersers can reduce seed flow across fragments, especially for plants whose fruits are not handled effectively by smaller animals. Evolutionary and demographic consequences would occur only if supported by longer-term evidence.
6. After a large fruit-eating bird declines, a smaller bird begins consuming fruits from several plants it rarely visited before. What process does this observation illustrate?
Explanation. Interaction rewiring occurs when surviving species form or strengthen links after community change. Researchers must still measure seed handling, dispersal distance, deposition quality, and recruitment before concluding that the new interactions fully compensate for the loss.
7. Researchers map the seed shadow of a tree population. What does a seed shadow describe?
Explanation. A seed shadow describes where seeds are deposited and how their density changes with distance and direction from source plants. Comparing seed shadows can reveal how dispersers and landscape features influence movement.
8. Two forests have seed-dispersal networks with the same number of links. Why might they respond differently to the loss of one disperser species?
Explanation. A count of links does not capture interaction frequency, seed treatment, movement distance, deposition quality, or which species share partners. These properties can change how strongly the loss of a particular disperser affects ecological function.
9. Which experiment would best test whether greater disperser diversity stabilizes seedling recruitment during seasonal drought?
Explanation. Replication and assigned diversity treatments reduce confounding, while comparable drought exposure and repeated recruitment measurements test stability of the ecological function. A purely observational contrast cannot separate diversity from site or weather differences.
10. A bird consumes many fruits but crushes nearly every seed, whereas a tortoise consumes fewer fruits and deposits most seeds intact in suitable soil. Which conclusion is best supported?
Explanation. Fruit consumption or removal is not equivalent to effective dispersal. Seed survival, treatment during gut passage, dispersal distance, deposition site, and later recruitment determine the quality of an interaction.
11. A restoration project reconnects two forest fragments with a vegetated corridor. Which result would provide the strongest evidence that the corridor restored seed-dispersal function?
Explanation. Direct evidence of seeds moving across the former barrier and recruiting at suitable sites links the corridor to restored function. Vegetation cover or animal presence alone does not show that effective seed dispersal occurred.
12. Across 25 islands, sites with more disperser species also have more diverse seedling communities. Why does this pattern alone not prove that disperser richness caused seedling diversity?
Explanation. The correlation is consistent with a disperser-diversity effect, but shared environmental or biogeographic factors could produce the same pattern. Experiments, longitudinal changes, or statistical controls for plausible confounders would strengthen causal inference.
📘 Want a full structured course and official-style practice tests? Browse top-rated AP Exams prep books and courses. Some links are affiliate links; we may earn a commission at no cost to you.
advertisement
FAQ
What is a seed-dispersal network?
It represents fruiting plant and seed-disperser species as nodes connected by observed interactions. Link frequency and effectiveness can be added to show more than simple presence or absence.
Does more connectivity always make a seed-dispersal network stable?
No. Stability also depends on species identity, interaction strength, functional redundancy, dispersal quality, habitat structure, rewiring, and the type of disturbance.
How is effective seed dispersal different from fruit removal?
Fruit removal records an early interaction. Effective dispersal also considers whether seeds survive handling, reach suitable locations, germinate, and contribute to recruitment.