Ten questions on how the planet\'s systems work, each explained by mechanism rather than by argument.
Environmental literacy is mostly a matter of knowing a handful of mechanisms well. This quiz covers them: the composition of the atmosphere, how greenhouse gases trap heat, what photosynthesis exchanges, and the difference between renewable and fossil energy. It includes the headline international agreements as historical facts. The explanations describe the physical process and stay clear of policy debate, which is a separate discussion from the science underneath it.
Every question in this quiz is listed below with its correct answer and the reasoning behind it. Play first if you would rather not see the answers — or read through as a study sheet.
Play it insteadAnswer: B. Nitrogen
Why: Nitrogen makes up about 78 per cent of the atmosphere and oxygen about 21. Carbon dioxide is a small fraction of one per cent, but disproportionately important for temperature.
Answer: A. Carbon dioxide
Why: Carbon stored underground for millions of years is released as carbon dioxide when burned. It is the largest single driver of current warming.
Answer: D. Heat
Why: Certain gases let sunlight through but absorb the infrared heat the surface radiates back. Without any greenhouse effect the planet would be far too cold for life.
Answer: C. Ultraviolet radiation
Why: Ozone in the stratosphere absorbs most incoming ultraviolet B radiation. The Montreal Protocol phased out the chemicals thinning it, and the layer is now slowly recovering.
Answer: C. Oxygen
Why: Plants take in carbon dioxide and water and release oxygen as a by-product. Essentially all atmospheric oxygen originates from this process.
Answer: A. Coal
Why: Coal formed from plant matter buried and compressed over millions of years. The other three generate energy without burning stored carbon.
Answer: B. Solar
Why: Solar energy is replenished continuously on any human timescale. The others exist in fixed quantities and are consumed when used.
Answer: B. 2015
Why: It was adopted at the 2015 UN climate conference and entered force the following year. Countries set their own emissions targets under it.
Answer: C. Absorb carbon dioxide
Why: Growing trees take up carbon dioxide and store the carbon in wood and soil. Clearing them removes that uptake and often releases the stored carbon as well.
Answer: A. Energy
Why: Recycling aluminium uses a small fraction of the energy needed to smelt it from ore. It can be recycled repeatedly without meaningful loss of quality.
Planet Systems has 10 questions and takes about 6 minutes to finish. It is rated Easy and sits in our Environment & Climate category.
Each of the 10 correct answers adds 10 XP, up to 100 XP for a clean run. Wrong answers cost you nothing, and your full question-by-question review is shown at the end.
Yes. All 10 questions carry a written explanation of why the correct answer is right, so the quiz works as a study sheet as well as a test.
Yes, as often as you like. The questions and the answer options are reshuffled on each run, and you can use Practice Mistakes afterwards to retry only the ones you missed. No account is needed to play.
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