Biology crossword puzzle

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Across
  1. 2. dioxide: a gas that is a waste product of cells when they burn food.
  2. 6. hair-like structures found in the air passageways of the respiratory system.
  3. 7. the basic unit of any living thing. Some living things consist of only a single cell, while others are composed of trillions of cells
  4. 10. a disease that damages the alveoli, making it difficult to get enough oxygen.
  5. 11. cords: two folds of tissue in the larynx that vibrate when air passes over them and produce sound, including the basic sounds of speech.
  6. 12. to take air in and expel it out of the lungs.
  7. 15. tiny blood vessels.
  8. 17. breathe in.
  9. 19. a cavity behind the nose and mouth that leads to the trachea and oesophagus.
  10. 20. rate: the rate, or number of breaths per minute, at which we breathe.
  11. 22. the tube that carries food from the back of the throat to the stomach.
  12. 23. two bag-like organs that fill most of the chest. The lungs draw in air through the trachea and bronchi.
  13. 24. a part of the respiratory system between the pharynx and the trachea. It houses the vocal cords.
Down
  1. 1. pair of tubes between the trachea and the lungs.
  2. 3. a large muscle below the ribs that helps a person breathe.
  3. 4. a breathing disorder in which the air passageways in the lungs constrict, causing shortness of breath.
  4. 5. one of the lung's smallest air passageways.
  5. 8. the movement of oxygen from the atmosphere to cells and carbon dioxide from cells to the atmosphere.
  6. 9. tiny air sacs in the lungs.
  7. 13. breathe out.
  8. 14. the air passageway between the pharynx and the bronchi.
  9. 16. a flap of tissue that prevents food from going down the trachea rather than the oesophagus.
  10. 18. system: the group of organs that take in oxygen from the air and release carbon dioxide.
  11. 21. a sticky substance in the nose that traps dirt, dust and other particles.
  12. 22. a gas in air that humans and most living things need to live.
  13. 24. capacity: the volume of air that the lungs can hold.