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Multiple Choice
Which of the following statements correctly describes carbon fixation in photosynthesis?
A
It is the absorption of light energy by chlorophyll pigments.
B
It is the process by which inorganic carbon dioxide is incorporated into organic molecules during the Calvin cycle.
C
It is the conversion of glucose into pyruvate during glycolysis.
D
It is the splitting of water molecules to release oxygen in the light-dependent reactions.
Verified step by step guidance
1
Understand the concept of carbon fixation: Carbon fixation is a process in photosynthesis where inorganic carbon dioxide (CO₂) is converted into organic molecules, such as sugars, during the Calvin cycle.
Identify the role of the Calvin cycle: The Calvin cycle is part of the light-independent reactions of photosynthesis, where CO₂ is incorporated into a 3-carbon molecule (3-phosphoglycerate) using the enzyme RuBisCO.
Eliminate incorrect options: Absorption of light energy by chlorophyll pigments occurs in the light-dependent reactions, not during carbon fixation. Similarly, splitting of water molecules to release oxygen is part of the light-dependent reactions, not the Calvin cycle.
Clarify the difference between glycolysis and photosynthesis: Glycolysis is a process in cellular respiration where glucose is broken down into pyruvate, which is unrelated to carbon fixation in photosynthesis.
Conclude that the correct description of carbon fixation is: It is the process by which inorganic carbon dioxide is incorporated into organic molecules during the Calvin cycle.