Optometry Admission Test (OAT) Practice

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Study for the Optometry Admission Test (OAT). Dive into multiple choice questions, each with explanations and helpful hints. Enhance your knowledge and prepare for success in your exam!

Each practice test/flash card set has 50 randomly selected questions from a bank of over 500. You'll get a new set of questions each time!

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Which cycle is primarily responsible for fixing carbon during photosynthesis?

Krebs cycle
Calvin cycle
Light reactions
Dark reactions

The correct answer is: Calvin cycle

The Calvin cycle is the process that primarily fixes carbon during photosynthesis. This cycle takes place in the stroma of chloroplasts and involves the conversion of carbon dioxide from the atmosphere into organic compounds that can be used by plants. During the Calvin cycle, carbon dioxide is incorporated into a five-carbon sugar molecule, ribulose bisphosphate (RuBP), through the action of the enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO). This process ultimately leads to the production of glucose and other carbohydrates. The purpose of the Calvin cycle is to transform inorganic carbon dioxide into organic biomass, which is essential for plant growth and energy storage. This cycle does not directly depend on light but is driven by the energy produced during the light reactions of photosynthesis, which generate ATP and NADPH.