The primary gas released by plants during photosynthesis is oxygen. Through this essential process, plants convert sunlight into energy, utilizing carbon dioxide and water to produce glucose and oxygen. This not only sustains the plant’s growth and metabolism but also contributes significantly to the Earth's atmosphere. Oxygen released during photosynthesis is vital for the survival of most living organisms, as it is required for respiration. This natural process highlights the intricate connections within ecosystems and underscores the importance of plants in maintaining ecological balance and air quality.