during photosynthesis oxygen in glucose comes from

1. oxygen in air
2. water
3. carbon dioxide
4. both (2) & (3)

Photosynthesisis a process used by plants and other organisms to convertlightenergy, normally from thesun, into chemical energy that can be laterreleasedto fuel the organisms' activities. This chemical energy is stored incarbohydrate molecules, such assugars, which are synthesized fromcarbon dioxideandwater– hence the name photosynthesis. The oxygen part of the glucose formed comes from carbon dioxide.