Question

The oxygen liberated during photosynthesis by green plants comes from ______.

Options

• glucose

• water

• carbon dioxide

• chlorophyll

Answer 1

The oxygen liberated during photosynthesis by green plants comes from water.

Explanation:

During the light-dependent phase of photosynthesis, solar energy captured by chlorophyll is used to split water molecules H₂O inside the chloroplasts. This specific biochemical process is called photolysis of water. The chemical reaction splits water into hydrogen ions (protons), electrons, and molecular oxygen O₂. Hydrogen ions and electrons are used to generate chemical energy to build sugars, while the resulting oxygen gas is released as a byproduct into the atmosphere.

The breakdown can be simplified as:

\[\ce{2H2O ->[Light Energy] 4H+ + 4e- + O2↑}\]