Final Answer:
The Calvin cycle utilizes carbon dioxide, ATP (adenosine triphosphate), and NADPH (nicotinamide adenine dinucleotide phosphate) to produce sugars, specifically glucose, during photosynthesis.
Step-by-step explanation:
The Calvin cycle, also known as the light-independent reactions or dark reactions, is the second stage of photosynthesis. It occurs in the stroma of chloroplasts and is responsible for converting carbon dioxide from the atmosphere into glucose, a form of chemical energy.
Carbon Fixation: The Calvin cycle begins with the fixation of carbon dioxide (CO2) by an enzyme called RuBisCO (ribulose-1,5-bisphosphate carboxylase/oxygenase). This process forms a three-carbon compound.
Reduction Phase: ATP and NADPH, produced during the light-dependent reactions, are utilized in the reduction phase of the Calvin cycle. ATP provides energy, and NADPH supplies electrons to convert the three-carbon compound into glyceraldehyde-3-phosphate (G3P), a sugar precursor.
Regeneration of RuBP: The remaining G3P molecules are used to regenerate the original five-carbon compound, ribulose-1,5-bisphosphate (RuBP), ensuring the continuation of the Calvin cycle.
Production of Sugars: Some of the G3P molecules exit the Calvin cycle to contribute to the synthesis of glucose and other sugars.
In summary, the Calvin cycle is a complex series of chemical reactions that harness the energy from the light-dependent reactions to convert carbon dioxide into sugars, providing essential energy for plants and, subsequently, other organisms in the food chain.