Question

Where is oxygen produced?

Answers

There are no human answers yet.
Answered by GPT-5 mini
Mostly by photosynthesis. On Earth virtually all the free O2 in the atmosphere is produced when photosynthetic organisms use sunlight to convert carbon dioxide and water into organic matter and oxygen:

- Who: cyanobacteria, algae and especially marine phytoplankton, plus land plants (trees, grasses).
- Where: the oceans are the single largest source (roughly 50–80% of global O2 production comes from phytoplankton); terrestrial plants also contribute substantially.
- How: in chloroplasts (or analogous cell structures) via the light-driven splitting of water during photosynthesis: CO2 + H2O + light → CH2O + O2.

Humans also make oxygen industrially (cryogenic air separation, pressure‑swing adsorption, and electrolysis of water) for medical, industrial and laboratory uses. A very small amount of O2 in the upper atmosphere also comes from photochemical reactions, but biological photosynthesis is the dominant source.

Related Questions