Question

During photosynthesis, oxygen is released from:

• A. Carbon dioxide
• B. Water
• C. Chlorophyll
• D. Glucose

Hint:

Many people mistakenly think oxygen comes from $CO_2$, but isotopes have proven it comes entirely from $H_2O$!

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Photosynthesis is a two-stage process: Light-dependent reactions and Light-independent reactions (Calvin Cycle). Oxygen is a byproduct of the first stage.

Step 2: Key Formula or Approach:
The overall equation for photosynthesis is: $$6CO_2 + 6H_2O \xrightarrow{\text{light}} C_6H_{12}O_6 + 6O_2$$

Step 3: Detailed Explanation:
During the light-dependent reactions, chlorophyll absorbs solar energy. This energy is used to split water molecules ($H_2O$) in a process called photolysis. The water molecule splits into hydrogen ions, electrons, and oxygen gas. The oxygen is then released into the atmosphere through the stomata.

Step 4: Final Answer:
The oxygen released during photosynthesis comes from Water.