The primary gas involved in photosynthesis is carbon dioxide (CO2). During photosynthesis, plants, algae, and some bacteria utilize sunlight to convert carbon dioxide and water into glucose and oxygen. This process occurs in the chloroplasts of plant cells, where chlorophyll captures light energy. The produced glucose serves as an energy source for the plants, while oxygen is released into the atmosphere as a byproduct. Photosynthesis is essential not only for the growth and survival of plants but also for producing the oxygen that most life forms on Earth rely on, making it a critical aspect of Earth's ecosystem.