Question

1. a plant makes glucose during photosynthesis. glucose consists of the elements carbon, hydrogen, and oxygen. what is the source of the elements for the glucose that the plant makes? construct an explanation.

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Explanation:

In photosynthesis, plants use carbon dioxide ($\ce{CO_2}$) from the air (source of carbon and oxygen) and water ($\ce{H_2O}$) from the soil (source of hydrogen and oxygen) to produce glucose ($\ce{C_6H_{12}O_6}$) and oxygen. The chemical equation for photosynthesis is $\ce{6CO_2 + 6H_2O \xrightarrow[\text{chlorophyll}]{\text{light energy}} C_6H_{12}O_6 + 6O_2}$. So carbon comes from $\ce{CO_2}$, hydrogen and oxygen (partially) from $\ce{H_2O}$, and oxygen (partially) from $\ce{CO_2}$.

Answer:

The carbon in glucose comes from carbon dioxide ($\ce{CO_2}$) in the air. The hydrogen and some of the oxygen in glucose come from water ($\ce{H_2O}$) absorbed by the plant's roots from the soil. The remaining oxygen in glucose also comes from carbon dioxide. During photosynthesis, plants use light energy, $\ce{CO_2}$, and $\ce{H_2O}$ to synthesize glucose (and oxygen) via the reaction $\ce{6CO_2 + 6H_2O \xrightarrow[\text{chlorophyll}]{\text{light energy}} C_6H_{12}O_6 + 6O_2}$, where the atoms of $\ce{C}$, $\ce{H}$, and $\ce{O}$ from $\ce{CO_2}$ and $\ce{H_2O}$ are rearranged to form glucose.