24.

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Across
  1. 3. Biology
  2. 4. Biology sections?
  3. 7. Biology topic
  4. 8. Biology abbr.
  5. 9. Biology classes?
Down
  1. 1. Biology class sighting
  2. 2. Biology class topic
  3. 4. SCIENCE Biology
  4. 5. Biology book, e.g.
  5. 6. Biology opening