Respiratory and Excretory System

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Across
  1. 3. A colorless, poisonous chemical in the tobacco plant.
  2. 6. The process of inhaling and exhaling.
  3. 8. Two spongy saclike respiratory organs.
Down
  1. 1. The act or process of discharging waste.
  2. 2. A pair of organs in the excretory system.
  3. 4. The two branches of the trachea that extend into the lungs.
  4. 5. A muscular membrane of the body.
  5. 7. Cartilaginous tube descending from the larynx to the bronchi.