Underlying Biological Structures and Functions

​A hollow muscular organ that pumps blood throughout the blood vessels to various parts of the body

by repeated, rhythmic contractions is the?

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Answer: Heart

​An organ that serves as the center of the nervous system in all vertebrate and most invertebrate

animals is?

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Answer: The Brain

​ The _____ is the most complex organ in a vertebrate's body.

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Answer: brain

​_________ are usually considered the most important cells in the brain.

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Answer: Neurons

​The ______ is the essential respiration organ in many air-breathing animals.

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Answer: Lung