________ is the source of the oxygen gas released by a photosystem.C6H12O6Chlorophyll aCO2H2O

The source of the oxygen gas released by a photosystem is H2O (Water).

Here's the step by step explanation:

1. Photosynthesis is the process by which green plants, algae and some bacteria use sunlight to synthesize foods with the help of chlorophyll pigments.

2. During photosynthesis in green plants, light energy is captured and used to convert water, carbon dioxide, and minerals into oxygen and energy-rich organic compounds.

3. The process of photosynthesis is divided into two main parts: Light dependent reactions and light independent reactions. The light dependent reactions occur in the thylakoid membrane and generate ATP and NADPH, which are energy molecules.

4. In the light-dependent reactions, one molecule of the pigment chlorophyll absorbs one photon and loses one electron. This electron is passed to a modified form of chlorophyll called pheophytin, which passes the electron to a quinone molecule, starting the flow of electrons down an electron transport chain that leads to the ultimate reduction of NADP to NADPH.

5. In addition, this creates a proton gradient energy is used to produce ATP (adenosine triphosphate), which is used in the light-independent reactions.

6. The splitting of water is associated with the light-dependent reactions, which produce oxygen as a waste product. This process is also known as photolysis. In photolysis, water molecules are broken down into hydrogen ions, electrons, and oxygen gas.

7. The oxygen gas is released into the atmosphere, the hydrogen ions are used to produce ATP, and the electrons are used to reduce NADP into NADPH.

So, the source of the oxygen gas released by a photosystem during photosynthesis is water (H2O).