Biology I / Photosynthesis and the Oxygen Revolution
Practice question · Sort into groups

Sort each consequence by whether the Great Oxidation Event caused it directly.

Groups: Direct consequence · Not a consequence of oxygenation

Hints
  1. Oxygen is chemically reactive, so it affected both life and rock.
  2. The structure of the genetic code was fixed long before oxygen accumulated.
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Direct consequence: Mass extinction of obligate anaerobes, Formation of the ozone layer, Aerobic respiration becomes possible, Banded iron formations are deposited

Not a consequence of oxygenation: The genetic code becomes a triplet code

Why

Free oxygen poisoned anaerobes, oxidised dissolved iron into the banded formations, formed ozone, and opened the aerobic route. The triplet code was established far earlier and has nothing to do with atmospheric chemistry.

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