Which reactant in the photosynthesis equation is the source of hydrogen for sugar molecules?

• A. Oxygen (\(O_2\))
• B. Water (\(H_2O\))
• C. Carbon dioxide (\(CO_2\))
• D. Glucose (\(C_6H_{12}O_6\))

Answer: (B)

Verified step by step guidance

1. Understand the process of photosynthesis: Photosynthesis is the process by which plants, algae, and some bacteria convert light energy into chemical energy stored in glucose (\(C_6H_{12}O_6\)). The general equation for photosynthesis is: \(6CO_2 + 6H_2O + light \rightarrow C_6H_{12}O_6 + 6O_2\).
2. Identify the components of the photosynthesis equation: The reactants are carbon dioxide (\(CO_2\)) and water (\(H_2O\)), and the products are glucose (\(C_6H_{12}O_6\)) and oxygen (\(O_2\)).
3. Determine the source of hydrogen in glucose: Glucose (\(C_6H_{12}O_6\)) contains hydrogen atoms. These hydrogen atoms must come from one of the reactants in the photosynthesis equation.
4. Analyze the role of water (\(H_2O\)): Water molecules are split during the light-dependent reactions of photosynthesis in a process called photolysis. This releases hydrogen ions (\(H^+\)), which are used to form glucose during the Calvin cycle.
5. Conclude that water (\(H_2O\)) is the source of hydrogen: Based on the splitting of water during photolysis, the hydrogen atoms in glucose originate from water (\(H_2O\)).