2.5.15

Oxygen in the Atmosphere

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The Rise of Oxygen in the Earth's Atmosphere

Photosynthesis increased the atmospheric concentration of oxygen.

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What is photosynthesis?

  • Photosynthesis is the process in which light energy is used to produce glucose and oxygen from carbon dioxide and water.
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Photosynthetic organisms

  • Algae were the first photosynthetic organisms to evolve. This happened about 2.5-2.7 billion years ago.
  • Photosynthesising plants then began to evolve over the next billion years. This led to an ever-increasing rate of oxygen accumulating in the atmosphere.
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The evolution of more complex organisms

  • More complex life forms, such as animals, began to evolve once a threshold concentration of oxygen was reached.

Jump to other topics

1Biology

1.1Cells, Tissues & Organs

1.2Reproduction & Variation

1.3Ecological Relationships & Classification

1.4Digestion & Nutrition

1.5Plants & Photosynthesis

1.6Biological Systems & Processes

2Chemistry

2.1Particles

2.2Chemical Reactions

2.3Atoms, Elements, Compounds

2.4The Periodic Table

2.5Materials & the Earth

2.6Reactivity

2.7Energetics

2.8Properties of Materials

3Physics

3.1Energy

3.2Forces & Motion

3.3Waves

3.4Electricity & Magnetism

3.5Matter

3.6Space Physics

4Thinking Scientifically

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