Conservation, Systems & Environmental Design — Chapter Practice, Grade 12

Join conservation evidence, feedback, risk, and a complete design-and-monitoring proposal.

Problem 1

Which listed activity directly removes habitat and separates remaining habitat patches?
  1. Scientists collecting a few specimens for study
  2. Natural predators hunting their usual prey
  3. Zoos keeping some animals in captivity
  4. Habitat loss and fragmentation from clearing and dividing land
Answer and explanation

Habitat loss and fragmentation from clearing and dividing land

Clearing and dividing land can reduce available habitat and connectivity. The relative importance of threats varies among ecosystems and requires evidence.

Problem 2

An invasive species is best described as
  1. a non-native species that spreads rapidly in a new area and harms native species
  2. any large predator at the top of a food chain
  3. a native species that has lived in an ecosystem for thousands of years
  4. any species that is currently close to extinction
Answer and explanation

a non-native species that spreads rapidly in a new area and harms native species

Invasive species are non-natives that, lacking natural predators or competitors in the new range, spread out of control and damage native populations.

Problem 3

A coastal wetland covering 500 hectares is drained and developed until only 75 hectares remain. What percentage of the original wetland habitat was lost?
Answer and explanation

85 %

Area lost = 500 - 75 = 425 hectares; 425 ÷ 500 = 0.85, or 85% of the wetland lost.

Problem 4

Describe two ecosystem services that healthy, biodiverse ecosystems provide to people, and explain why losing biodiversity puts them at risk.
Answer and explanation

Examples include pollination of crops by insects, filtering and cleaning of water by wetlands and forests, fertile soil built by soil organisms, flood control, and climate regulation. These services depend on many interacting species; as biodiversity declines, the organisms that perform them are lost and the services weaken or fail, directly harming the food, water, and protection people rely on.

Problem 5

Scientists estimate that species are going extinct roughly 100 to 1,000 times faster than the natural 'background' rate. Why does this concern them?
  1. Because a higher extinction rate must mean the number of species is increasing
  2. Because extinctions at this pace outrun the rate at which evolution produces new species, so total biodiversity is falling and lost species can never be recovered
  3. Because faster extinction means new species also appear faster, keeping biodiversity constant
  4. Because extinction has never happened before in Earth's history
Answer and explanation

Because extinctions at this pace outrun the rate at which evolution produces new species, so total biodiversity is falling and lost species can never be recovered

Extinction is permanent, and losing species far faster than new ones evolve means biodiversity is steadily and irreversibly declining.

Problem 6

How can fragmentation threaten a population without reducing total habitat area immediately? Show the reasoning, not just the conclusion.
Hints

Absence of detection is not proof of absence.

Answer and explanation

It can restrict movement, gene flow and access to resources and increase edge effects.

Problem 7

What evidence supports a conservation outcome beyond a publicity claim?
Hints

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

Answer and explanation

Comparable abundance, reproduction, habitat or functional measures with methods, baseline and uncertainty disclosed.

Problem 8

Trend interpretation requires matched observation conditionsTrend interpretation requires matched observation conditionsObserved individuals04080120123Survey year indexMatched-effort illustrationChanging-effort illustration
Synthetic count examples with deliberately different possible observation processes; not a correction to an actual field record.
Interpret the supplied visual. What records are essential alongside a count series?
Answer and explanation

Survey area, method, effort, timing, observer/detection conditions and relevant uncertainty.

Observed abundance depends on true population, sampled extent, effort and detectability. A declining count may signal ecological loss, but an observation model is needed to separate that from reduced survey effort or changed visibility. The two hypothetical curves are reminders of this ambiguity, not proof that any particular real decline is only a measurement artifact. Preserve all source labels and compare repeated standardized monitoring or an appropriate detection-adjusted analysis.

Survey area, method, effort, timing, observer/detection conditions and relevant uncertainty.

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

A population estimate falls from 500 to 350 under comparable methods. Find percent decline. Explain why this does not prove global extinction or identify a unique cause.
Answer and explanation

Decline=(500−350)/500=30%. Living individuals remain in the defined population, and the record alone cannot distinguish survival, reproduction, movement or the pressures affecting them.

Decline=(500−350)/500=30%.

Living individuals remain in the defined population, and the record alone cannot distinguish survival, reproduction, movement or the pressures affecting them.

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.

Problem 10

OpenSciEd graph titled observed Masai giraffe numbers, 1977–2015 in Kenya, with a high early peak, lower later counts and sharp fluctuations; its displayed data credit names IUCN and Muller et al. (2018).
Preserve the source title and observed Masai giraffe/Kenya scope. The drawn trace does not supply a complete annual 1977–2015 table. Historical Masai giraffe observations in Kenya · OpenSciEd · 7.5 Ecosystem Dynamics, Lesson 10 graph; data source retained in image, source, CC BY 4.0. Figure excerpt rendered from the PDF and resized for the web.
Describe a broad pattern without inventing exact missing annual values. Explain why this source alone neither measures all global giraffes nor establishes a unique cause of decline.
Answer and explanation

The displayed observed counts fluctuate, with an early high peak and many lower later counts. It is a Kenya-scoped observed-count graph, not a global census. Search effort, coverage, detection and demographic/pressure evidence are needed to interpret actual abundance and causes. The title’s interval must not be used to fabricate unplotted exact annual values.

Read source labels, scope, axes and intentional omissions.

Use the complete local explanation to draw a justified mechanism or calculate a supported quantity.

State what is observed, what is assumed and what evidence remains needed.

Response criteria

  • Interpret the source labels, units and scope accurately.
  • Explain the relevant mechanism with a labeled model or supported calculation.
  • Identify a meaningful assumption, uncertainty or missing comparison.

Problem 11

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 12

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 13

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 14

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 15

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 16

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 17

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 18

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 19

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.

Problem 20

Reservoir 600 units,outflow 30 units/year. Estimate residence time.
Hints

Write the relationship first; substitute with consistent units.

Answer and explanation

20 years

600/30=20.

Problem 21

Is positive feedback necessarily desirable?
Answer and explanation

No; positive means amplifying, not good.

Response criteria

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

Problem 22

Storage begins 100 units; inputs 45 and outputs 20. Find final storage.
Hints

List the given quantities, select a relationship, and check units before substituting.

Answer and explanation

125 units

100+45−20=125.

Problem 23

Why might equal expected-loss options have different consequences?
Answer and explanation

They may differ in extreme outcomes, who is exposed, reversibility, and uncertainty.

Response criteria

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

Problem 24

A shortage causes groundwater pumping that further lowers groundwater levels. What loop is plausible? Show the reasoning, not just the conclusion.
Hints

Negative does not mean undesirable.

Answer and explanation

A reinforcing depletion loop if the lower levels worsen shortage and induce more pumping.

Problem 25

Why pair probability with consequence in a risk assessment?
Hints

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

Answer and explanation

Rare severe events and frequent minor events differ; neither likelihood nor severity alone describes risk adequately.

Problem 26

Expected loss does not summarize every aspect of riskExpected loss does not summarize every aspect of riskScenarioProbabilityConsequence unitsExpected valueA0.1010010B0.50157.5InterpretationDefined intervalComparable scaleNot worst-caseseverityExposure, vulnerability and consequence distribution also matter.
Illustrative probabilities and comparable consequence units, not a forecast or insurance estimate.
Interpret the supplied visual. Which scenario has larger expected value, and which has the larger single-event consequence?
Answer and explanation

A has expected 10 versus 7.5 for B, and its consequence 100 is also larger; other scenarios could separate those rankings.

A simple expected loss multiplies event probability by a consequence on a defined comparable scale, summing across mutually specified outcomes. Probability needs an interval and reference class. Exposure concerns who or what is in contact with the hazard; vulnerability affects the damage given that contact. Two options can have similar expected loss but different worst cases, inequality or uncertainty. Explain these dimensions rather than treating one average as the entire decision.

A has expected 10 versus 7.5 for B, and its consequence 100 is also larger; other scenarios could separate those rankings.

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 27

Event A has probability 0.05 and consequence 200 units; B has probability 0.20 and consequence 40. Find expected losses and explain why the smaller expected value need not settle the choice.
Answer and explanation

A=10 units; B=8 units. B has lower expected loss, but worst-case severity, uncertainty, distribution, constraints and priorities still need transparent consideration.

A=10 units; B=8 units.

B has lower expected loss, but worst-case severity, uncertainty, distribution, constraints and priorities still need transparent consideration.

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.

Problem 28

A20W reduction runs 1500h/year. Find saved energy.
Hints

Write the relationship first; substitute with consistent units.

Answer and explanation

30 kWh/year

.020×1500=30.

Problem 29

Why keep a baseline in a comparison?
Answer and explanation

It makes change and added benefit measurable rather than assuming every new option is better.

Response criteria

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

Problem 30

An upgrade costs 500 units and saves 100 units/year. Find simple payback.
Hints

List the given quantities, select a relationship, and check units before substituting.

Answer and explanation

5 years

500/100=5, excluding other costs.

Problem 31

Cost 900 units,annual savings 300. Find simple payback.
Hints

Write the relationship first; substitute with consistent units.

Answer and explanation

3 years

900/300=3.

Problem 32

An initial concentration is 10 mg/L and removal is 40%. Find final concentration. Show the reasoning, not just the conclusion.
Hints

Use provided datasets for analysis; do not consume experimental treated water.

Answer and explanation

10×(1−0.40)=6 mg/L; this calculation alone does not establish safety.

Problem 33

What should an evidence-based design report include?
Hints

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

Answer and explanation

Problem, criteria, mechanism, alternatives, methods, data, uncertainty, trade-offs, limitations and a monitoring/revision plan tied to measurable outcomes.

Problem 34

Test alternatives and sensitivity before choosing oneTest alternatives and sensitivity before choosing oneEqual-service optionAnnual energyUp-front inputConstraint checkA120 units40 unitsMeets statedserviceB90 units80 unitsTest repair /accessDifference30 units/year40 extra unitsBreak-even≈1.33yearsA ranking remains conditional on lifespan and comparable service.
Hypothetical energy-only comparison with equal service assumed; not real product data.
Interpret the supplied visual. What if B lasts only one year before replacement?
Answer and explanation

Its 40-unit extra up-front burden exceeds its 30-unit one-year saving, before replacement impacts and other criteria are considered.

An alternatives analysis compares multiple feasible designs under the same service definition. Here B uses 30 fewer energy units per year but has 40 additional up-front units, giving an energy break-even around 1.33 years if conditions persist. Lifespan, maintenance and service quality can change that conclusion. Examine a plausible range and identify what would reverse the ranking; report non-energy criteria alongside the selected account rather than hiding them inside one unsupported score.

Its 40-unit extra up-front burden exceeds its 30-unit one-year saving, before replacement impacts and other criteria are considered.

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 35

A proposed change saves 12 W for 1500 h/year while providing the same service. Its extra production energy is 24 kWh. Find annual saving and energy break-even; name one pilot measure beyond energy.
Answer and explanation

Annual saving=0.012×1500=18 kWh. Energy break-even=24/18≈1.33 years under fixed use/lifespan assumptions. Measure service adequacy, reliability, actual hours, access or maintenance as a separate pilot outcome.

Annual saving=0.012×1500=18 kWh.

Energy break-even=24/18≈1.33 years under fixed use/lifespan assumptions.

Measure service adequacy, reliability, actual hours, access or maintenance as a separate pilot outcome.

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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