Human Biology

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Across
  1. 3. clot the blood at the site of injury
  2. 6. di oxide toxic waste of respiration
  3. 8. gas needed for respiration
  4. 9. section sof chromosomes
  5. 12. molecules that make up structures like muscles.
  6. 14. carry pure blood from heart to body
  7. 15. structures that open and close between heart chambers
Down
  1. 1. respiration takes place
  2. 2. carry impure blood to heart from body
  3. 4. contain vocal cords
  4. 5. one of four nitrogenous bases of DNA
  5. 7. versions of genes
  6. 10. divides left and right parts of heart
  7. 11. substances that cause change in DNA
  8. 13. bones that surround and protect lungs