Final answer:
Jan Ingenhousz proposed that the source of carbon in plants is carbon dioxide (CO2), which is utilized during photosynthesis to produce glucose (C6H12O6) along with oxygen.
Step-by-step explanation:
Ingehousz proposed that the source of carbon in plants is CO₂. This is supported by the process of photosynthesis, during which plants convert carbon dioxide (CO₂) and water (H₂O) into glucose (C₆H₁₂O₆) using solar energy.
The overall chemical equation for photosynthesis is 6CO₂ + 6H₂O + energy → C₆H₁₂O₆ + 6O₂, showing that carbon dioxide is reduced and combined with water to produce carbohydrates such as glucose, which plants can then use for energy or convert into larger carbohydrates like starch or cellulose.