Evaluating Environmental Solutions — Drills · Grade 9 Science

Chapter: Resources & Human Decisions

What these drills covers

By the end of Evaluating Environmental Solutions you should be able to:

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

Vocabulary used: criterion, constraint, life-cycle perspective.

Problem 1

Water use falls from 80 to 60 units. Find percent reduction.
Answer and explanation

25 %

20 ÷ 80 × 100 = 25.

Problem 2

Name one trade-off for replacing pavement with a planted surface.
Answer and explanation

It may reduce runoff and add habitat but require space, maintenance, or different accessibility provisions.

Problem 3

Evaluating an environmental solution should begin with
  1. its cost alone
  2. clear criteria and constraints
  3. public opinion
  4. the newest technology
Answer and explanation

clear criteria and constraints

Without stated criteria there is nothing to evaluate options against.

Problem 4

A life-cycle assessment considers impacts
  1. only during use
  2. from extraction through manufacture, use and disposal
  3. only at disposal
  4. only in one country
Answer and explanation

from extraction through manufacture, use and disposal

A solution can shift impact from one stage to another rather than reducing it.

Problem 5

Option A costs $600,000 and saves 400 tonnes of carbon a year. What is the cost per tonne saved, in dollars?
Answer and explanation

1500 $/tonne

600,000 / 400 = $1,500 per tonne per year.

Problem 6

A solution that reduces emissions but displaces a community has
  1. no trade-off
  2. a trade-off that should be stated
  3. failed entirely
  4. succeeded entirely
Answer and explanation

a trade-off that should be stated

Costs falling on particular people belong in the evaluation rather than outside it.

Problem 7

Explain why the cheapest option per tonne of carbon saved is not automatically the best.
Answer and explanation

Cost per tonne ignores who bears the cost, how reliable the saving is, whether it can be scaled, and what else the option affects — habitat, water, employment. A cheap option with large uncertainty or serious side effects may be worse overall than a dearer one that is dependable. The figure is one criterion among several rather than the decision itself.

Response criteria

  • State a scientifically accurate conclusion.
  • Show the data, mechanism, or calculation that supports it.
  • Include units, conditions, or limits where relevant.

Problem 8

Describe what a proposal should include so that someone else could judge it.
Answer and explanation

The objective stated measurably, the evidence that the proposed action produces the effect claimed with its uncertainty, the full cost including maintenance and monitoring, who bears the costs and who gains, the trade-offs and side effects, and what will be measured afterwards to tell whether it worked. Without the last item the proposal cannot be evaluated once implemented.

Response criteria

  • State a scientifically accurate conclusion.
  • Show the data, mechanism, or calculation that supports it.
  • Include units, conditions, or limits where relevant.

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