Photosynthesis is significant in nature because it is the process by which green plants, algae, and some bacteria convert light energy, usually from the sun, into chemical energy stored in glucose molecules. This process not only provides oxygen for organisms to breathe but also serves as the foundation of the food chain, as plants are the primary producers that other organisms rely on for energy. Additionally, photosynthesis helps regulate the Earth's atmosphere by removing carbon dioxide and producing oxygen, making it essential for maintaining life on our planet.