Designing & Evaluating a Habitat Solution — Practice · Grade 7 Science

Chapter: Ecological Evidence & Environmental Design

What this practice covers

By the end of Designing & Evaluating a Habitat Solution you should be able to:

8 questions, written answer, multiple choice and numeric, each with a worked explanation.

Vocabulary used: criterion, constraint, prototype, iteration, cost effectiveness.

Problem 1

How is a criterion different from a constraint?
Answer and explanation

A criterion evaluates success; a constraint limits allowable options, such as a maximum budget or available area.

Problem 2

Why not compare one design’s best trial with another’s worst?
Answer and explanation

It selects evidence unfairly and can misrepresent typical performance; compare the full relevant records.

Problem 3

Does a lower-cost design automatically win?
Answer and explanation

No. Cost is one criterion and feasibility limit; outcomes and other requirements also matter.

Problem 4

What makes a proposed revision useful?
Answer and explanation

It targets an identified limitation or tradeoff and can be evaluated with a defined measurement.

Problem 5

Illustrative plans within a 100-token budget: A costs 80 and reduces runoff from 20 to 8 L; B costs 60 and reduces it from 20 to 10 L. Both satisfy the same stated space requirement; later maintenance is unknown. Calculate reductions, compare reduction per token, and recommend a feasible option under an explicit criterion with a next test.
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 6

Plan C achieves the largest reduction but costs 130 tokens under the same 100-token limit. Is it currently feasible?
Answer and explanation

No. It exceeds the stated constraint unless the budget or plan changes. A desirable result does not remove a feasibility 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 7

Which is a constraint?
  1. Maximum budget of 100 tokens
  2. Wanting more cover
  3. Liking a color
  4. A general hope
Answer and explanation

Maximum budget of 100 tokens

The budget limits feasible options; criteria measure desired performance.

Problem 8

A model runoff falls from 24 L to 9 L. Find reduction.
Answer and explanation

15 L

24−9=15 L under the supplied comparison.

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