Question

The basic source of oxygen in photosynthesis is

• A. Chlorophyll
• B. \(CO_2\)
• C. Water
• D. Solar energy

Hint:

A common misconception is that the oxygen comes from \(CO_2\). Remember that photosynthesis splits water to release oxygen. Experiments using isotopes of oxygen (like \(^{18}O\)) have confirmed this.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Photosynthesis is the process used by plants, algae, and some bacteria to convert light energy into chemical energy, through a process that converts carbon dioxide and water into glucose (sugar) and oxygen.

Step 2: Key Formula or Approach:
The overall chemical equation for photosynthesis is:
\[ 6CO_2 + 6H_2O \xrightarrow{\text{Light Energy}} C_6H_{12}O_6 + 6O_2 \]

Step 3: Detailed Explanation:
During the light-dependent reactions of photosynthesis, light energy is used to split water molecules in a process called photolysis.
The splitting of water (\(H_2O\)) releases electrons, protons (\(H^+\)), and oxygen atoms. The oxygen atoms then combine to form molecular oxygen (\(O_2\)), which is released as a byproduct.
The oxygen in carbon dioxide (\(CO_2\)) ends up in the glucose (\(C_6H_{12}O_6\)) and in the water molecules produced during the process, not in the released oxygen gas.

Step 4: Final Answer:
Therefore, the source of the oxygen gas released during photosynthesis is water.