Air and Respiratory System

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Across
  1. 1. Fish carry out gaseous exchange in this organ.
  2. 3. This gas make up 21% of air.
  3. 7. Energy is released through this process.
  4. 8. The _________ will move upwards and outwards when we breathe in.
Down
  1. 2. Gaseous exchange takes place here in humans.
  2. 4. This tube carries air into our lungs.
  3. 5. Inhalation and exhalation is also known as ___________.
  4. 6. This muscular layer is not part of the respiratory system, but helps in breathing.