OSAT Physical Science Practice Test

Photosynthesis is primarily driven by light-driven, oxidation-reduction reactions. In this process, energy from sunlight is absorbed by chlorophyll and other pigments in the chloroplasts of plant cells. This energy facilitates the conversion of carbon dioxide and water into glucose and oxygen. The reactions are divided into two stages: the light-dependent reactions, where light energy is captured and used to produce ATP and NADPH, and the light-independent reactions (Calvin cycle), where ATP and NADPH are utilized to synthesize glucose from carbon dioxide.

During the light-dependent reactions, water molecules are oxidized, releasing oxygen as a byproduct. Meanwhile, carbon dioxide is reduced in the Calvin cycle to form glucose. This fundamental oxidation-reduction chemistry is what makes photosynthesis possible, turning solar energy into chemical energy stored in carbohydrates.

Other options, while related to chemical processes in various contexts, do not capture the primary mechanism that enables plants to convert light energy into chemical energy during photosynthesis.