Human Impact & Stewardship — Drills · Grade 9 Science

Chapter: Resources & Human Decisions

What these drills covers

By the end of Human Impact & Stewardship you should be able to:

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

Vocabulary used: stewardship, sustainability, conservation, per-capita consumption.

Problem 1

Which human activity most directly increases atmospheric carbon dioxide?
  1. Planting trees
  2. Burning fossil fuels
  3. Wind generation
  4. Recycling
Answer and explanation

Burning fossil fuels

Combustion transfers long-stored fossil carbon into the atmosphere.

Problem 2

Habitat fragmentation harms populations mainly by
  1. increasing total area
  2. isolating populations and reducing movement between them
  3. adding predators
  4. improving soil
Answer and explanation

isolating populations and reducing movement between them

Smaller isolated groups are more vulnerable to chance loss and lose genetic variation.

Problem 3

Stewardship means
  1. using resources without limit
  2. managing resources with future users in mind
  3. leaving land untouched always
  4. selling resources quickly
Answer and explanation

managing resources with future users in mind

It balances present use against long-term capacity.

Problem 4

Emissions fall from 420 to 357 million tonnes. What is the percentage reduction?
Answer and explanation

15 %

(420 − 357)/420 × 100 = 15 percent.

Problem 5

Which measure addresses soil erosion most directly?
  1. Cover crops and contour planting
  2. Increasing fishing quotas
  3. Building taller chimneys
  4. Deeper ploughing
Answer and explanation

Cover crops and contour planting

Keeping roots in the ground and slowing runoff holds soil in place.

Problem 6

A city recycles 180 of 600 tonnes of waste a week. What percentage is recycled?
Answer and explanation

30 %

180/600 × 100 = 30 percent.

Problem 7

Explain why an environmental decision usually involves trade-offs rather than a single right answer.
Answer and explanation

Measures that reduce one harm often create costs elsewhere: a dam supplies low-carbon electricity but floods habitat and displaces people, and a quota protects a fish stock while reducing incomes now. The costs and benefits also fall on different people and at different times. Evidence can estimate what each option would produce, but choosing between them involves weighing interests, which is a judgement rather than a measurement.

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 evidence would show whether a conservation measure is working.
Answer and explanation

A baseline measured before the measure began, the same indicator measured the same way afterwards, and a comparison area that did not receive the measure so a general trend can be distinguished from the measure's effect. The indicator should respond to what the measure changes, and monitoring should continue long enough for natural year-to-year variation to be separated from a real change.

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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