20.1 Vocab

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Across
  1. 3. An animal that has a backbone and an endoskeleton
  2. 5. A group of cells with a common purpose.
  3. 7. A hard outer covering that some animals have instead of bones.
  4. 10. The outer layer of cells that develops into the nervous system and skin.
  5. 12. Animals that lack a backbone.
  6. 13. A two cell layer sac with an open end.
Down
  1. 1. Type of fertilization where sperm meet the egg inside of the body.
  2. 2. The middle layer of cells that become the muscular, circulatory, and respiratory systems.
  3. 4. An internal support system.
  4. 6. Organisms that cannot create their own food.
  5. 8. Type of fertilization that requires an aquatic environment.
  6. 9. A fertilized egg.
  7. 10. The inner layer of gastrula cells that will become the digestive organs.
  8. 11. A hollow, fluid filled group of cells.