The tool below drills mechanisms first, responses second.
WeSolve+ reads the whole document and writes the questions for you
Upload your PDF, photograph your notebook, or point the camera. WeSolve+ writes questions from that material, explains why each answer is right, reads the chapter back to you as a podcast, and remembers every item you missed until you own it.
The tool below is a small browser-only tool and it is not WeSolve+: paste a few lines and text rules turn them into cards on the spot. The real app, the one that uses AI, is behind the link above.
Unit 9 planetary cases, from your own notes
This is a browser-only tool, and that is all it isIt splits the text you paste by rule, and nothing else. WeSolve+ is a different thing entirely: it reads your whole PDF with AI, writes the reasoning behind every question, speaks the chapter back to you, and remembers what you missed so it can return it. Try the real app now, free!
What you paste is what gets carded. Fixed rules split the text and nothing outside it is known, which makes the paste itself the real decision.
Ozone: the solved case, and why it worked
Stratospheric ozone absorbs hard ultraviolet; CFCs, stable enough to reach the stratosphere, freed chlorine that catalysed ozone destruction, thinning a seasonal Antarctic hole. The Montreal Protocol banned the culprits and the layer is healing: few chemicals, clear mechanism, available substitutes. The exam pairs it with climate to ask why one treaty worked and the other struggles.
The greenhouse mechanism, ranked by gas
Greenhouse gases pass sunlight and absorb the infrared the surface returns, warming the lower atmosphere: the effect is natural, the enhancement is not. Gases rank by potency and lifetime, carbon dioxide most abundant, methane far more potent per molecule and shorter lived, nitrous oxide and fluorinated gases smaller but heavy hitters. Rank by the right axis for the question asked, and cite fossil combustion, agriculture and land clearing as the sources.
Warming compounds through ice, seas and storms
The effects chain: glaciers and sea ice retreat, darker surfaces absorb more heat, seas rise by melt and by thermal expansion, storms and droughts intensify, ranges and seasons shift toward the poles and earlier springs. Feedback is the graded concept, albedo loss and thawing permafrost amplifying what started it, which is why projections curve rather than climb straight. Write the chain in order and name one feedback.
The ocean pays twice: heat and acid
The ocean absorbs most added heat and much of the carbon dioxide, and the dissolved gas forms carbonic acid: acidification lowers pH and spends the carbonate that shell and reef builders budget on. Corals bleach under heat stress and thin under acid, a double bill. The chemistry connects back to the acid base unit, and the exam rewards writing the reaction chain, gas to acid to carbonate scarcity.
Biodiversity pays the running bill
HIPPCO lists the pressures in rough order: habitat destruction, invasive species, population growth, pollution, climate change, overexploitation. Island and specialist species fall first; generalists inherit. The response toolkit runs from protected areas and corridors through CITES trade controls to endangered species law, and the scored move is matching the tool to the named pressure, not reciting the acronym.
What to photograph for Global Change
Your mechanism chains and treaty notes. Related: Unit 8, photo to quiz and pricing.
Sources used on this page
- College Board, AP Environmental Science
- Ozone depletion
- Montreal Protocol
- Greenhouse gas
- Ocean acidification
- CITES
- Active recall
- Spaced repetition
- Testing effect
- Forgetting curve
- Generation effect
- Judgment of learning
- Metacognition
- Desirable difficulty
- Distributed practice
- Formative assessment
- Flashcard
- Cloze test
- Multiple choice
- Test (assessment)
- Educational assessment
- Advanced Placement
- Curriculum
- Study skills
- Study guide
- Note-taking
- Overlearning
- Instructional scaffolding
- Item analysis
- Mastery learning
| Case | The mechanism | The response |
|---|---|---|
| Ozone hole | CFC chlorine catalysis | Montreal ban, healing layer |
| Greenhouse warming | Infrared absorbed, enhanced | Frameworks still arguing |
| Sea level rise | Melt plus expansion | Adaptation planning |
| Ocean acidification | Carbon dioxide to acid | Emissions cuts only |
| Range shifts | Warming moves habitats | Corridors, assisted moves |
| Species trade | Overexploitation | CITES permits and bans |
What does AP Environmental Science Unit 9 cover?
Global change: ozone depletion and its treaty, the greenhouse mechanism and climate impacts, ocean acidification, and biodiversity loss with its responses.
Why did the Montreal Protocol succeed?
Few chemicals, a clear mechanism and ready substitutes: banning CFCs was cheap relative to the damage, and the layer is measurably healing.
How do greenhouse gases rank?
By two axes: abundance and potency times lifetime. Carbon dioxide leads on volume; methane is far more potent per molecule and shorter lived.
Why does the ocean acidify?
It absorbs carbon dioxide, which forms carbonic acid, lowering pH and spending the carbonate that shell and reef builders need.
What is HIPPCO for?
Ordering the pressures on biodiversity, habitat loss first; the graded skill is matching each named pressure to its response tool.
Can I build questions from my own Unit 9 notes?
Yes. Point the camera at the pages or send the PDF, and the questions stay within that material instead of ranging across the term.
Last updated: 2026-08-15