The graph shows the concentration of CFCs (chlorofluorocarbons) in the atmosphere from 1970 to 2020. Between 1990 and 2000, the concentration stopped increasing and began to decrease. Which statement best explains this change?

Q: How do I try a free CIE Biology question?

Just tap any of the four options on this page — no signup, no card, nothing to install. You'll see the correct answer and a full mark-scheme-style explanation within a second. Each visit shows a fresh randomly-picked question from the live CIE IGCSE Biology bank, so you can keep refreshing to try different ones before deciding whether to create a free account for daily access.

Q: Is Kramizo really free for CIE Biology students?

Yes — completely free. Every student gets 45 questions a day on the free plan, across any board and any subject, with no card required and no trial countdown. Kramizo's optional Pro plan removes the daily cap and adds analytics, but the free plan is genuinely free forever. We make money from the small percentage of students who choose to upgrade — not from selling data or ads.

Q: Are the Biology questions aligned to the CIE IGCSE syllabus?

Every question is written against the published CIE IGCSE Biology syllabus and reviewed for accuracy before being added to the bank. We match the command words (state, describe, explain, evaluate), mark allocations, and difficulty tier you'll see on real CIE past papers. Explanations are written in the style of official examiner mark schemes so students learn exactly what marks are being awarded for.

Question

The graph shows the concentration of CFCs (chlorofluorocarbons) in the atmosphere from 1970 to 2020. Between 1990 and 2000, the concentration stopped increasing and began to decrease. Which statement best explains this change?

Accepted Answer

international agreements banned production and use of CFCs — Award 1 mark for international agreements banned production and use of CFCs. The Montreal Protocol (1987) led to global reduction in CFC production. A is incorrect — CFCs are very stable and persist for decades. C is incorrect — trees do not absorb CFCs. D is incorrect — ozone does not absorb CFCs; CFCs break down ozone.

Answer

international agreements banned production and use of CFCs

Answer

increased tree planting absorbed CFCs from the atmosphere

Answer

CFCs naturally break down rapidly in the lower atmosphere

Answer

the ozone layer regenerated and absorbed the excess CFCs

One real Biology question.No signup. 30 seconds.

One real Biology question.
No signup. 30 seconds.