Biological Evidence...

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Across
  1. 6. The study of similarities and differences among structures of different species
  2. 7. The science of the development of embryos from fertilization to birth
  3. 8. The study of gene structure and function
  4. 9. body part of organisms that are similar in structure and position but different in function
Down
  1. 1. body parts that perform a similar function but differ in structure
  2. 2. Body parts that have lost their original function through evolution
  3. 3. develops into gills in some organisms
  4. 4. a protein required for cellular respiration
  5. 5. The source of variations upon which natural selection acts