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Multiple Choice
The carbon that plants need for photosynthesis comes from:
A
carbon dioxide in the atmosphere
B
proteins absorbed from the soil
C
carbonates in the soil
D
glucose stored in roots
Verified step by step guidance
1
Understand the process of photosynthesis: Photosynthesis is the process by which plants convert light energy into chemical energy, using carbon dioxide (CO₂) and water (H₂O) as raw materials to produce glucose (C₆H₁₂O₆) and oxygen (O₂).
Identify the source of carbon for photosynthesis: The carbon atoms in glucose (C₆H₁₂O₆) come from carbon dioxide (CO₂) in the atmosphere, which plants absorb through small openings in their leaves called stomata.
Eliminate incorrect options: Proteins absorbed from the soil are not a source of carbon for photosynthesis; they are used for other metabolic processes. Similarly, carbonates in the soil are not directly used in photosynthesis. Glucose stored in roots is a product of photosynthesis, not a raw material.
Focus on the correct option: Carbon dioxide (CO₂) in the atmosphere is the correct source of carbon for photosynthesis, as it provides the carbon atoms that are incorporated into glucose during the Calvin cycle.
Conclude the reasoning: Based on the understanding of photosynthesis and the elimination of incorrect options, the correct answer is that the carbon plants need for photosynthesis comes from carbon dioxide in the atmosphere.