Conservation, Systems & Environmental Design — Chapter review · Physics & Environmental Science, Grade 12

(a) habitat loss, (b) invasive species, (c) overexploitation.

(a) Clearing the mangrove removes the natural habitat, so this is habitat loss/destruction — the largest driver overall. (b) A non-native vine spreading and harming native trees is an invasive species. (c) Killing elephants faster than the population can replace itself is overexploitation. All three appear in the HIPPO list of biodiversity threats.

75%.

Area lost = 8,000 - 2,000 = 6,000 hectares. Dividing by the original area: 6,000 ÷ 8,000 = 0.75, or 75% of the forest habitat lost. Only a quarter of the original forest remains.

Fragmentation isolates populations, shrinks patches below what some species need, and increases harmful edge effects, so the divided habitat supports less biodiversity than the same area kept intact.

Even with the same total area, breaking a habitat into isolated patches causes several problems. Populations in different patches are cut off from one another, reducing gene flow and making local extinctions more likely. Wide-ranging or large species may need more continuous space than any single small patch provides. And more edge means more of the habitat is exposed to drying winds, sunlight, predators, and invasive species that penetrate from the surrounding farmland. So fragmentation can reduce biodiversity even when the raw acreage is unchanged — which is why connecting habitat with corridors is a key conservation strategy.

About 5 Earths.

Earths needed = footprint ÷ biocapacity per person = 8.0 gha ÷ 1.6 gha = 5.0. If every person on the planet consumed at this level, humanity would need five Earths' worth of resources and waste absorption — a stark illustration that the highest-consumption lifestyles cannot scale to the whole global population.

It shows that when science identifies a global pollutant and nations coordinate policy to phase it out, an Earth system can recover — evidence that climate change is also solvable through international, system-level action rather than individual effort alone.

The Montreal Protocol worked because nearly every country agreed to the same binding phase-out of CFCs, replacing them with safer chemicals across entire industries at once. Because the change was made at the level of laws and whole industries — not left to individual consumers — it reached the true source of the problem, and the ozone layer began healing within decades. This is encouraging for climate change: the largest emissions come from how societies produce energy, move goods, and grow food, which are shaped by policy and infrastructure. Individual choices help and build momentum, but coordinated, system-level policy has the leverage to cut emissions at their source — just as it did for ozone.

They can improve movement and gene flow but also transport disease or invasives; compare evidence and target species.

Response criteria

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

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.

A baseline, defined service and boundary, predicted outcomes, resource/impact accounting, trade-offs, and monitoring.

Response criteria

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

Old=1000 units; new=840; saving=160 units=16%, smaller than the40% per-use reduction. Adequate service quality, access or reliability needs a separate measure.

Old=1000 units; new=840; saving=160 units=16%, smaller than the40% 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.

Write the relationship first; substitute with consistent units.

25 units

120−95=25.

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.

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.

Measured outcomes, method, comparison period, controls for confounders, schedule, and revision criteria.

Response criteria

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

Write the relationship first; substitute with consistent units.

3 years

900/300=3.

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.