In oxygenic photosynthesis, which molecules are the primary reactant inputs used to produce sugars and oxygen?

• A. Carbon dioxide and water
• B. Glucose and oxygen
• C. Nitrogen gas and ammonia
• D. ATP and NADPH

Answer: (A)

Verified step by step guidance

1. Understand the process of oxygenic photosynthesis, which occurs in plants, algae, and cyanobacteria, where light energy is used to convert carbon dioxide and water into glucose and oxygen.
2. Identify the primary reactant molecules that enter the photosynthetic pathway: carbon dioxide (CO\_2) from the atmosphere and water (H\_2O) absorbed by the plant roots.
3. Recognize that during photosynthesis, light energy splits water molecules (photolysis), releasing oxygen (O\_2) as a byproduct and providing electrons and protons for the synthesis of sugars.
4. Note that glucose (a sugar) and oxygen are the products of photosynthesis, not the reactants, so they cannot be the primary inputs.
5. Conclude that the correct primary reactant inputs for oxygenic photosynthesis are carbon dioxide and water, which are converted into sugars and oxygen through the photosynthetic process.