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Answer: Atrioventricular node
The AV node serves as an electrical relay station, slowing the electrical current sent by the sinoatrial (SA) node before the signal is permitted to pass down through to the ventricles.
Answer: Benthic Zone
The presence of sediment layers at the benthic zone provides many nutrients and adds greatly to species richness. Because the benthic zone has such a range of depths, many kinds of organisms may live there.