Across
- 3. Where the gas exchange happens
- 6. They get oxygen through tracheal system (air tube system).
- 8. Breathing in
- 9. Organs that fill with air
Down
- 1. Breathing out
- 2. A muscle that moves up and down when we breathe
- 4. Fish use their ____ to get oxygen.
- 5. Plants take in oxygen and carbon dioxide through ____.
- 7. It goes up when we inhale and down when we exhale