Question

The oxygen produced in photosynthesis comes from what molecule?

Answer 1

From `H_2O`.

Explanation:

The light reaction of photosynthesis uses energy from sunlight to split water molecules. The product of this reaction is hydrogen ions and oxygen gas.

The hydrogen ions will be used by later steps of photosynthesis towards the end goal of making carbohydrates.

Here is a look at aquatic plants carrying out the light reaction, the video also gives a brief summary of photosynthesis.

Here is a more thorough discussion of photosynthesis.

Hope this helps!