The Oxygen Released in Photosynthesis Comes from ____

Question

The oxygen released in photosynthesis comes from ____.  
A) carbon dioxide
B) glucose
C) ribulose bisphosphate
D) water
E) atmospheric oxygen

Accepted Answer

The oxygen released in photosynthesis comes from splitting water molecules during the light reactions. The water molecule is split into oxygen and hydrogen ions, and the oxygen is released into the atmosphere as a byproduct of photosynthesis.