Chemosynthesis: process that creates energy for ecosystems in the absence of sunlight. Uses chemicals (like sulfur), carbon dioxide, and water to create sugar and sulfur compounds.

Photosynthesis: when plants use sunlight, carbon dioxide and water to create sugars (energy) and oxygen to supply energy for ecosystems.

Respiration: opposite of photosynthesis. Plants use glucose (sugar) and oxygen and release carbon dioxide, water, and energy.