In oxygenic photosynthesis, which molecule is consumed (used up) as a reactant in the overall process that produces glucose and oxygen?

• A. Chlorophyll a
• B. Carbon dioxide ($C_1{O}_2$)
• C. Oxygen ($O_2$)
• D. Glucose ($C_6{H}_{12}{O}_6$)

Answer: (B)

Verified step by step guidance

1. Understand that oxygenic photosynthesis is the process by which plants, algae, and cyanobacteria convert light energy into chemical energy, producing glucose and oxygen as products.
2. Recall the overall balanced chemical equation for oxygenic photosynthesis: \$6\ \text{CO}_2 + 6\ \text{H}_2\text{O} + \text{light energy} \rightarrow \text{C}_6\text{H}_{12}\text{O}_6 + 6\ \text{O}_2$.
3. Identify the reactants in this equation: carbon dioxide (\(\text{CO}_2\)), water (\(\text{H}_2\text{O}\)), and light energy. Chlorophyll a is a pigment that captures light but is not consumed as a reactant.
4. Note that glucose (\(\text{C}_6\text{H}_{12}\text{O}_6\)) and oxygen (\(\text{O}_2\)) are products, not reactants, so they are not consumed in the process.
5. Conclude that carbon dioxide (\(\text{CO}_2\)) is the molecule consumed as a reactant in the overall photosynthesis process that produces glucose and oxygen.