To determine what supplies the hydrogen used in the formation of glucose during photosynthesis, let's first recall the overall equation for photosynthesis:
[tex]\[ 6CO_2 + 6H_2O + light \ energy \rightarrow C_6H_{12}O_6 + 6O_2 \][/tex]
In the process of photosynthesis, plants take in carbon dioxide (CO₂) from the atmosphere and water (H₂O) from the soil. The light energy absorbed by chlorophyll is used to convert these reactants into glucose (C₆H₁₂O₆) and oxygen (O₂).
Now, let’s analyze which component supplies the hydrogen:
- Light energy: Light energy acts as a catalyst; it induces the reaction but does not provide any atoms of hydrogen.
- Carbon dioxide (CO₂): The chemical formula of carbon dioxide is CO₂, meaning it contains carbon and oxygen but no hydrogen.
- Chlorophyll: Chlorophyll is the pigment in plants that absorbs light energy, but it is not a reactant in the formation of glucose and hence does not supply hydrogen.
- Water (H₂O): The chemical formula of water is H₂O, indicating it contains two hydrogen atoms for each oxygen atom.
Given that water is the only reactant that contains hydrogen, it is clear that water (H₂O) supplies the hydrogen used in the formation of glucose during photosynthesis.
Therefore, the correct answer is:
Water
