Across
- 3. The ability to do work
- 4. A molecule with breath in
- 6. A group of atoms joined in a particular way
- 9. Only oxygen can enter this system
Down
- 1. Where the heart is and blood flows
- 2. The body's use of molecules for energy and growth
- 5. A system where food is broken down
- 7. Breaks down into amino acids
- 8. Breaks down into glucose