Which best explains why a parasite needs a host? 1. Parasites use their host as a energy source.
2. Parasites use the immune system of their host.
3. Parasites use their host to increase their oxygen supply.

Match each description with the correct form of energy. 1. energy of an object's position above the ground. 2. stored in the bonds of atoms and molecules 3. stored in the nucleus of an atom 4. energy of vibrating molecules 5. movement of objects used to do work 6. created by vibrations in electric and magnetic fields chemical energy mechanical energy heat gravitational energy light nuclear energy