biology 5

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Across
  1. 5. Nerve cell that transmits electrical signals.
  2. 6. Protein that acts as a catalyst in biochemical reactions.
  3. 8. Infectious agent that replicates only inside the living cells of an organism.
  4. 9. Chemical messenger produced by glands.
  5. 10. Junction between two neurons.
Down
  1. 1. Protein in red blood cells that carries oxygen.
  2. 2. Substance that stimulates an immune response for protection against diseases.
  3. 3. Branchlike structure of a neuron that receives signals.
  4. 4. Protein produced by the immune system to neutralize pathogens.
  5. 7. Long projection of a neuron that conducts electrical impulses.