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9.1.3 How oxygen increased
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The source of atmospheric oxygen

The source of atmospheric oxygen

Oxygenic photosynthesis may have existed by about 2.7 billion years ago, but significant atmospheric oxygen accumulation began later, during the Great Oxidation Event about 2.4 billion years ago. Land plants spread much later, during the last few hundred million years.

9.1.3 How oxygen increased Lesson

  1. GCSE
  2. /Chemistry
  3. /9.1.3 How oxygen increased

Step-by-step lessons on AQA GCSE Chemistry 9.1.3 How oxygen increased. Each one builds up to exam-style questions. Nail the core quantitative topics — moles, balancing equations and calculations — early on, since they underpin higher-tier questions across every paper and topic.

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