Ecological Evidence & Environmental Design — Chapter review · Life Science & Scientific Inquiry, Grade 7
Five focused units, a three-session investigation, chapter review, and chapter quiz.
Review the key ideas
Interactions & Ecosystem Change
Organisms interact through feeding, competition, and other relationships. Predation involves one organism consuming another; competition concerns overlapping use of limited resources. Some relationships benefit both participants, while others benefit one and harm another. The effect must be explained within a defined context rather than assigned by an organism’s reputation.
Biodiversity, Variation & Ecosystem Resilience
Biodiversity includes variety within species, among species, and across ecosystems. Species richness is the number of species detected within a defined survey; abundance describes individual counts. Two communities can have equal richness yet different abundance patterns. Detection method and survey effort influence both measures.
Human Activities, Habitat & Environmental Evidence
Human activities can change habitat, water movement, resource availability, and ecosystem relationships. Roads can divide habitat, land cover can affect runoff, and restoring vegetation can change conditions. Effects vary with design, place, scale, and time. A serious explanation traces a mechanism and observations rather than treating all activities as identical.
Sampling Ecosystems & Comparing Evidence
Ecologists often sample because counting every organism across a large habitat is impractical. A quadrat defines an area for selected observations; a transect organizes observations along a line. The method must fit the organism and question. A plant-count method does not automatically detect moving animals equally well.
Designing & Evaluating a Habitat Solution
Engineering begins with a defined problem, criteria for success, and constraints such as available space, resources, time, and safety. An ecological proposal should connect a mechanism with measurements. “Help nature” is too broad unless we define which conditions or functions are being improved.
Problem 1
Answer and explanation
Herbivory could reduce cover, while drought could also limit plant growth. The two recorded changes do not isolate either cause. Compare feeding observations, water conditions, and suitable reference plots across repeated intervals. Plant cover and counts are different measures, and the model should not claim a single cause from their association alone.
Cover falls 30 percentage points.
Herbivore count doubles.
Compare feeding effects with drought and a suitable matched observation.
Response criteria
- Explain the relevant biological process accurately.
- Use the supplied evidence and show calculation steps with units where needed.
- Connect a labeled model or mechanism with the claim.
- State an assumption, evidence limitation, or useful next observation.
Problem 2
Answer and explanation
No. Resource overlap and limitation, or effects on performance, need evidence.
Problem 3
Answer and explanation
The samples have equal richness and total count but different distributions. B is more even under the stated observations. These facts do not establish every functional relationship, genetic diversity, or response to future disturbances. Comparable repeated surveys and role-specific evidence would improve a resilience argument.
Richness is three in each.
Total abundance is ten in each.
A is more dominated by one species; B is more evenly distributed.
Response criteria
- Explain the relevant biological process accurately.
- Use the supplied evidence and show calculation steps with units where needed.
- Connect a labeled model or mechanism with the claim.
- State an assumption, evidence limitation, or useful next observation.
Problem 4
Answer and explanation
Yes. Individuals may belong to different numbers of species.
Problem 5
Answer and explanation
B has 8 L less recorded runoff in this illustrative trial. Vegetation-associated retention or infiltration could contribute under the stated comparison. The record does not establish all causal details, repeated performance, or absence of contaminants. More matched trials and separate water-quality measures are needed for stronger claims.
Difference: 18−10=8 L.
Connect vegetation and soil with possible infiltration or retention.
Separate runoff amount from all water-quality properties and identify the single-trial limit.
Response criteria
- Explain the relevant biological process accurately.
- Use the supplied evidence and show calculation steps with units where needed.
- Connect a labeled model or mechanism with the claim.
- State an assumption, evidence limitation, or useful next observation.
Problem 6
Answer and explanation
Actual effects depend on movement, species needs, alternative routes, and observations not given by the line alone.
Problem 7
Answer and explanation
The sample density is 3 plants/m² and the extrapolated count is 60 plants. It is an estimate assuming the plots represent the 20 m² habitat and detection is adequate. Patchiness, omitted zones, or missed plants could change the result. The supplied data do not establish an exact total.
Total count: 12 across 4 m².
Density: 12/4=3 plants/m².
Estimated larger count: 3×20=60.
Response criteria
- Explain the relevant biological process accurately.
- Use the supplied evidence and show calculation steps with units where needed.
- Connect a labeled model or mechanism with the claim.
- State an assumption, evidence limitation, or useful next observation.
Problem 8
Answer and explanation
Repeated sightings can involve one individual; the quantities answer different questions.
Problem 9
Answer and explanation
A provides the larger total reduction in the model, while B gives a slightly larger reduction per token. Both fit the initial budget. Either can be supported under an explicit priority, but maintenance, repeated performance, and real-setting transfer remain unknown. Recommend a matched repeated test and a maintenance estimate; fictional tokens are not actual prices.
A reduction: 12 L; B: 10 L.
A ratio: 12/80=0.15 L/token; B: 10/60≈0.167 L/token.
Choose using total reduction or cost efficiency and identify maintenance uncertainty.
Response criteria
- Explain the relevant biological process accurately.
- Use the supplied evidence and show calculation steps with units where needed.
- Connect a labeled model or mechanism with the claim.
- State an assumption, evidence limitation, or useful next observation.
Problem 10
Answer and explanation
A criterion evaluates success; a constraint limits allowable options, such as a maximum budget or available area.