answer this question and your answer sheet which part of the human body is more complex the heart or the circulatory system explain your answer number 2 why do you think it is important for you to study the levels of biological organization
Explanation: The heart is the key organ in the circulatory system. As a hollow, muscular pump, its main function is to propel blood throughout the body.
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Answer: the heart
Explanation: The heart is the key organ in the circulatory system. As a hollow, muscular pump, its main function is to propel blood throughout the body.