Across
- 4. Openings in an insect's body
- 7. Opening through which gases enter or exit
- 8. Voice box in a human
Down
- 1. Pipe which carries oxygen to the lungs
- 2. Branching of the trachea
- 3. Anaerobic respiration by yeast
- 5. Organism that breathes through skin
- 6. Structures in the body which are involved in breathing