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Difficulty: MediumPlant Biology and Photosynthesis

Vascular plants manufacture organic food molecules by capturing sunlight. Which gaseous compound is absorbed from the surrounding air to provide the necessary carbon atoms for glucose synthesis?

  1. A
    Oxygen (O2O_2)
  2. Carbon dioxide (CO2CO_2)Answer
  3. C
    Nitrogen (N2N_2)
  4. D
    Carbon monoxide (COCO)

Answer

Carbon dioxide (CO2CO_2)
Carbon dioxide (CO2CO_2) enters plant leaves through microscopic pores called stomata. Inside the chloroplast stroma, the carbon from CO2CO_2 is fixed through a cycle of biochemical reactions to form glucose (C6H12O6C_6H_{12}O_6).

Step-by-Step Solution

1
Identify the primary chemical equation and reactants of photosynthesis.
Photosynthesis uses radiant energy to combine carbon dioxide (CO2CO_2) and water (H2OH_2O) to produce glucose (C6H12O6C_6H_{12}O_6) and oxygen (O2O_2).
Understanding the overall chemical transformation reveals which molecule supplies the necessary elements.
2
Trace the origin of the carbon atoms found in the resulting glucose (C6H12O6C_6H_{12}O_6) molecule.
The carbon atoms come exclusively from atmospheric carbon dioxide (CO2CO_2) taken in through stomata.
Water provides hydrogen and electrons, while carbon dioxide provides both the carbon and oxygen backbone for carbohydrates.

Key Concept

Chemical reactants and carbon fixation in photosynthesis
Estimated Time:45s
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Topics

Plant Biology and Photosynthesis

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