respiratory system

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Across
  1. 1. diffusion, undeveloped respiratory organs
  2. 4. developed respiratory organs
  3. 6. the basic structure of ______ is to ensure the exchange of respiratory gases
  4. 8. present in fish
  5. 10. type of respiration where is exchange of gases between environment and lungs
Down
  1. 2. present in insects
  2. 3. breathing is exchange of gases between organism and …?
  3. 5. present in molluscs
  4. 7. type of respiration where is exchange of gases between blood and cells
  5. 9. respiratory organs of terrestrial vertebrates