Auxin: A hormone that plays a key role in phototropism by promoting cell elongation on the dark side of the plant, causing it to bend towards light.
Heliotropism: The directional growth of a plant in response to sunlight, but unlike phototropism, this involves the entire plant moving rather than just growing in one direction.
Photosynthesis:The process by which green plants use sunlight to synthesize foods with carbon dioxide and water.