Chapter 6

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Across
  1. 3. a cell that collects excess water in a flatworm
  2. 5. a heart chamber that receives blood returning to the heart
  3. 7. an organ of excretion found in vertebrates
  4. 11. the largest part of the brain that controls thought, memory, and body movement
  5. 13. an animal that eats plants
  6. 14. a substance that speeds up chemical changes
  7. 16. an animal that eats other animals
  8. 18. a way of getting food by straining it out of the water
Down
  1. 1. the part of the digestive tract of some animals that grinds food
  2. 2. a chemical signal that a nerve cell releases
  3. 4. the movement of materials from an area of high concentration to an area of low concentration
  4. 6. get rid of wastes or substances that are not needed
  5. 8. a message that travels along nerve cells
  6. 9. a chemical signal that glands produce
  7. 10. form and release, or give off
  8. 12. a heart chamber that pumps blood out of the heart
  9. 15. a bunch of nerve cells that are loosely connected
  10. 17. take in oxygen and give off carbon dioxide