Ecosystems, Matter & Energy — Chapter quiz · Life Science & Scientific Inquiry, Grade 7

Five focused units, a three-session investigation, chapter review, and chapter quiz.

Problem 1

Why might a consumer persist after one food source declines?
Answer and explanation

It may use other resources, migrate, or respond over time; the web shows possible connections rather than an immediate fixed outcome.

Problem 2

Why can one organism have more than one feeding position?
Answer and explanation

It can eat resources from different positions, such as both producers and other consumers. The web must show its actual resource relationships.

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 3

Does lower energy at the next position violate conservation?
Answer and explanation

No. Energy has other transfers and destinations; it is not all captured as next-level food.

Problem 4

A diagram gives 500 energy units and 100 animals. Can those labels be treated as the same measurement?
Answer and explanation

No. Energy amount and individual count are distinct quantities. A relationship between them requires further biological information.

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 5

Does evaporation destroy water molecules in this model?
Answer and explanation

No. It changes state and location while the water remains matter in the larger system.

Problem 6

Why does a carbon reservoir not necessarily return all its carbon to air each day?
Answer and explanation

Pathways have different rates and storage durations. Some carbon remains in tissues, soils, sediments, or other reservoirs over longer periods.

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 7

Why compare dry masses rather than wet masses alone?
Answer and explanation

Changing water content can alter wet mass without an equivalent change in the organic material being studied.

Problem 8

A leaf bag is weighed wetter at the end and gains mass. Does that prove organic material was created?
Answer and explanation

No. Added water or other material can change the measured mass. Define the boundary and compare dry material if that is the intended quantity.

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 9

Why can carrying capacity change?
Answer and explanation

Resources, habitat, and environmental conditions change, altering what the modeled setting can support.

Problem 10

A field count rises after a survey team doubles its observation time. Can the increase be assigned directly to population growth?
Answer and explanation

No. More effort can detect more individuals. Use comparable survey effort and methods before interpreting the difference as true growth.

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.

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