science

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Across
  1. 2. what we _______ in
  2. 3. the organ that helps is breathe
  3. 4. what is at the end of the respiratory system
  4. 6. the bit that goes up and down when we breathe
  5. 7. stays the same when we breathe in and out
Down
  1. 1. what we breathe out
  2. 5. the organ that pumps blood around the body