To survive, organisms use particular body parts to take in and get rid of certain materials. Animals take in food and oxygen. Some kinds of organisms absorb food, but animals take in food with their mouths. Plants take in water and minerals through their roots. A mineral is a substance found in nature that is not a plant or a(n) animal. To stay healthy, organisms must also get rid of wastes. Gases both enter and leave plants through leaves. Animals breathe gases in and out through lungs or gills.