Sugars can travel all throughout a plant. How do they "know" where to go?
◦ Sugar flows by gravity from the leaves to the roots.
◦ Phloem transport proteins carry the sugar molecules and bind to sugar receptors on cells where they are needed.
◦ Like diffusion down a concentration gradient, sugar flows from source to sink.
◦ Sugar adheres to water molecules and is pulled up by transpiration.