Which of the following substances is the origin of oxygen released as oxygen gas by green plants during photosynthesis?*watersugarcarbon dioxideribulose-1,5-biphosphate

The origin of oxygen released as oxygen gas by green plants during photosynthesis is water.

Here's the step-by-step process:

1. Photosynthesis begins with the absorption of light by chlorophyll in the chloroplasts of the plant cells.

2. This light energy is used to split water molecules (H2O) into hydrogen and oxygen. This process is known as photolysis of water.

3. The oxygen produced during photolysis is released into the atmosphere as oxygen gas.

4. The hydrogen ions (H+) produced are used in the next stages of photosynthesis to produce glucose (sugar) and other organic compounds.

So, while carbon dioxide and ribulose-1,5-biphosphate are involved in photosynthesis, they are not the source of the oxygen gas released. The sugar produced is a result of photosynthesis, not a source of oxygen. Therefore, the correct answer is water.