AP Biology: Seed Dispersal Kernel Matrix Permeability Practice Questions
Practice ecological data analysis with original AP Biology multiple-choice questions about seed movement through the landscape matrix. These questions emphasize resistance surfaces, functional connectivity, observed movement paths, detection probability, study design, model validation, and the limits of causal inference.
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. Researchers want to compare how readily birds disperse seeds through pasture and shaded agroforestry between forest patches. Which design provides the most direct comparison?
Explanation. Replicated, distance-matched routes with movement and deposition measurements directly compare passage through the two matrix types. Standardizing distance and sampling reduces important alternative explanations.
2. In a landscape resistance model, a paved area is assigned a higher resistance value than shrub cover. What does that assignment mean?
Explanation. Resistance represents the hypothesized difficulty of movement through a landscape feature. A higher value implies lower permeability, but the assigned values still require empirical validation.
3. A least-cost-path model predicts that dispersers avoid open fields. Which evidence would best test that prediction?
Explanation. Independent movement tracks directly test whether organisms follow the routes implied by the resistance surface. Reusing calibration data can exaggerate apparent predictive performance.
4. Seed traps are placed only in destination patches, with no measurements of dispersers entering the matrix. What can the study not determine by itself?
Explanation. Destination counts combine several processes. Without movement and detection data, low arrival cannot be assigned specifically to matrix entry, successful passage, or seed recovery.
5. A vegetated strip is added across an agricultural matrix. Which analysis gives the strongest evidence that it increased matrix permeability?
Explanation. A before-after comparison with controls helps distinguish the strip's effect from seasonal or regional changes. Replication and consistent measurement further strengthen the inference.
6. Two destination patches are the same straight-line distance from parent plants, but more genetically assigned seeds cross shaded agroforestry than open pasture. What is the most defensible conclusion?
Explanation. More assigned crossings support a permeability difference, but source production, disperser abundance, and detection must be considered. Arrival also does not guarantee germination or survival.
7. Detection probability for tagged seeds is lower in dense shrub matrix than in open ground. Which approach best supports a fair permeability comparison?
Explanation. Calibrating detection allows observed recoveries to be interpreted relative to the chance of finding a seed. Otherwise, habitat-specific recovery can be mistaken for a movement difference.
8. An observational study finds that seed dispersal distance is greater where the matrix contains more tree cover. Which claim goes beyond the evidence?
Explanation. An observational association does not establish a universal causal effect. Confounding, scale, species differences, and environmental context can all affect the relationship.
9. Which added measurement would most directly connect matrix permeability to the behavior of an animal seed disperser?
Explanation. Movement tracks reveal whether dispersers enter and traverse different matrix types. Linking those tracks to seed carrying or deposition provides a mechanistic bridge to seed dispersal.
10. Researchers assign resistance values using expert judgment. What is the best next step before treating the surface as a reliable measure of permeability?
Explanation. Expert judgment can generate hypotheses, but independent data are needed to test whether the resistance values predict real movement or dispersal patterns.
11. A low-resistance route also contains many more fruiting parent plants than a high-resistance route. Why is this a problem for estimating matrix permeability from seed arrivals?
Explanation. Arrival depends on both the number of seeds available and the probability of transport. Measuring or controlling source abundance helps avoid attributing a seed-supply effect to permeability.
12. A permeability model is trained using one dry season and evaluated by randomly splitting traps from that same season. Which validation would better test transfer across environmental conditions?
Explanation. Testing on a different season or year evaluates whether the model transfers when vegetation, resource availability, and disperser behavior change. A random within-season split may not capture that variation.
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FAQ
What is matrix permeability in landscape ecology?
Matrix permeability describes how readily organisms, propagules, or ecological flows move through the land cover between habitat patches. It depends on the disperser, the matrix type, spatial scale, and environmental conditions.
How is matrix permeability different from straight-line distance?
Straight-line distance measures separation, whereas permeability describes movement difficulty through the intervening landscape. Equally distant patches can differ in functional connectivity when their matrix types impose different costs.
Does a fitted resistance surface prove which landscape features control seed dispersal?
No. A fitted surface is a model whose predictions should be tested with independent movement, genetic assignment, or deposition data. Source abundance, detection, and correlated habitat variables can produce alternative explanations.