A researcher uses oxygen-18 isotopes to trace the source of evolved oxygen in plants. Which reactant is the source of this gas?
Q1. A researcher uses oxygen-18 isotopes to trace the source of evolved oxygen in plants. Which reactant is the source of this gas?
Answer: Water
Explanation: The oxygen released during photosynthesis comes specifically from the photolysis of water. CO2 provides oxygen for glucose, not for release.