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  1. GCSE
  3. Chemistry AQA

Chemistry

Chemistry cover artwork
  1. GCSE
  3. Chemistry AQA
  5. 9.1.3 How oxygen increased

9.1.3 How oxygen increased

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Revise AQA GCSE Chemistry 9.1.3 How oxygen increased with the question bank, lessons, revision guides, and flashcards.

Algae and plants produced the oxygen that is now in the atmosphere by photosynthesis, which can be represented by the equation: Algae first produced oxygen about 2.7 billion years ago and soon after this oxygen appeared in the atmosphere. Over the next billion years plants evolved and the percentage of oxygen gradually increased to a level that enabled animals to evolve.

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