Across
- 6. process of making energy in a cell
- 8. gas necessary for life
- 9. microscopic air sacs where oxygen and CO2 are exchanged
- 10. 2 tubes leading into lungs
- 11. to breathe out
Down
- 1. prepares air for lungs
- 2. tube that carries air to lungs
- 3. to breathe in
- 4. muscle that contracts and relaxes to enable breathing
- 5. waste product exhaled
- 7. produced in cells by combining O2 and food