Sustainability & Solutions — Practice · Grade 12 Science

Chapter: Conservation, Systems & Environmental Design

What this practice covers

By the end of Sustainability & Solutions you should be able to:

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

Vocabulary used: sustainability, ecological footprint, biocapacity, renewable energy, carrying capacity.

Problem 1

Which statement best defines sustainability?
  1. Protecting one endangered species while ignoring its habitat
  2. Using up resources as quickly as possible to grow the economy today
  3. Meeting the needs of the present without compromising the ability of future generations to meet their own needs
  4. Returning human society to a time before any technology existed
Answer and explanation

Meeting the needs of the present without compromising the ability of future generations to meet their own needs

Sustainability balances present needs against the future, ensuring that using resources today does not rob later generations of the ability to meet their own needs.

Problem 2

Which of the following is a renewable energy source?
  1. Coal
  2. Natural gas
  3. Oil
  4. Wind
Answer and explanation

Wind

Wind is naturally and continuously replenished; coal, natural gas, and oil are finite fossil fuels that release carbon when burned.

Problem 3

A country's average ecological footprint is 4.0 global hectares per person, while Earth can sustainably provide about 1.6 global hectares per person. If everyone lived this way, about how many Earths would humanity need?
Answer and explanation

2.5 Earths

Earths needed = footprint ÷ biocapacity = 4.0 ÷ 1.6 = 2.5 Earths.

Problem 4

Explain the difference between an individual action (like recycling at home) and a systemic solution (like a national shift to renewable energy), and why both are useful.
Answer and explanation

An individual action is a personal choice with a small direct effect but which, multiplied across many people and shifting norms, still matters. A systemic solution changes the rules, infrastructure, or technology for everyone at once — like replacing fossil-fuel power plants with renewables — so it has far greater leverage over the largest sources of impact. Both are useful: individual actions build support and habits, while systemic changes deliver the large-scale reductions that individual choices alone cannot.

Problem 5

The Montreal Protocol, in which nations agreed to phase out ozone-destroying chemicals, is often called an environmental success story. What makes it encouraging for tackling other global problems like climate change?
  1. It shows that coordinated international policy, guided by science, can reduce a global pollutant and let an Earth system begin to recover
  2. It shows that ignoring an environmental problem is the safest strategy
  3. It shows that global pollution problems solve themselves without any action
  4. It proves that individual recycling alone can fix any global problem
Answer and explanation

It shows that coordinated international policy, guided by science, can reduce a global pollutant and let an Earth system begin to recover

Nearly every nation agreed to phase out CFCs, and the ozone layer is now healing — evidence that science-guided global cooperation can solve a planet-scale environmental problem.

Problem 6

A project adds 200 units and saves 25/year. Find break-even. Show the reasoning, not just the conclusion.
Hints

Equivalent transport service and lifetime matter.

Answer and explanation

8 years.

Problem 7

Why evaluate affordability and access alongside environmental metrics?
Hints

State what the supplied observations or conditions establish, and separate that from any assumption.

Answer and explanation

A solution must deliver the intended service feasibly and equitably; a single environmental metric does not describe all design criteria.

Problem 8

A multi-criterion comparison makes value choices inspectableA multi-criterion comparison makes value choices inspectableCriterion / weightOption A scoreOption B scoreEnergy 0.543Affordability 0.324Repairability 0.252Weighted sum3.63.1Scores are illustrative preferences; weights must be disclosed.
Hypothetical scored decision example; no real product or policy is ranked.
Interpret the supplied visual. Recalculate if all weight goes to affordability. Which option ranks higher?
Answer and explanation

B, with score 4 versus A’s2. The ranking depends on the stated priority.

A decision matrix records alternatives, criteria, scores and any weights. Scores should use a defined scale and evidence basis; weights express priorities and sum consistently. Here A scores 3.6 and B3.1 with the displayed illustrative weights. That result is conditional, not proof that A is objectively best for every family or community. Test different justified weights and uncertain scores, especially where affected groups have different constraints.

B, with score 4 versus A’s2. The ranking depends on the stated priority.

Response criteria

  • Interpret labels, structures, axes, units and directions correctly.
  • Explain the physical or environmental relationship or mechanism.
  • Respect stated assumptions and distinguish observation from inference.

Problem 9

Energy per use falls from 10 to 6 units while annual uses rise from 100 to 140. Find old/new total and percent saving; state a separate service criterion.
Answer and explanation

Old=1000 units; new=840; saving=160 units=16%, smaller than the 40% per-use reduction. Adequate service quality, access or reliability needs a separate measure.

Old=1000 units; new=840; saving=160 units=16%, smaller than the 40% per-use reduction.

Adequate service quality, access or reliability needs a separate measure.

Response criteria

  • Use the stated measurements or conditions, with correct units.
  • Connect the result to the physical or environmental mechanism or evidence relationship.
  • Identify the assumption, model limit or further evidence requested.

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