Atoms and molecules are perpetually in motion . Increased temperature means greater molecular motion, so most materials expand when heated.
Plants make their own food, whereas animals obtain food by eating other organisms.
Decomposers transform dead organisms into simpler substances, which other organisms can reuse. Plants get energy by breaking down the sugars, releasing some of the energy as heat. Other organisms get energy to grow and function by breaking down the consumed body structures to sugars and then breaking down the sugars, releasing some of the energy into the environment as heat. Matter and energy are transferred from one organism to another repeatedly and between organisms and their physical environment. Several processes contribute to building up and wearing down the earth's surface.