Ice floats because it expands (kid version). The molecules are less dense in ice than when water (H2O) and the structure is different.
Hope that help
The nervous system is the major controlling, regulatory, and communicating system in the body. It is the center of all mental activity including thought, learning, and memory. Together with the endocrine system, the nervous system is responsible for regulating and maintaining homeostasis.
External respiration takes place in the lungs, where oxygen enters the blood and carbon dioxide enters the alveolar air. Internal respiration takes place in metabolizing tissues, where oxygen diffuses from the blood and carbon dioxide diffuses from the cells.
<h3>What is respiration?</h3>
Respiration is recognized as the movement of oxygen from the outside environment to the cells within tissues, as well as the removal of carbon dioxide in the opposite direction.
External respiration takes place in the lungs, where oxygen enters the blood and carbon dioxide enters the alveolar air.
Internal respiration takes place in metabolizing tissues, where oxygen diffuses from the blood and carbon dioxide diffuses from the cells.
Thus, in this way, external respiration and internal respiration are co-dependent.
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D. a cell wall.
reasoning: in a prokaryotic cell, they have no nucleus or organelles. a cell wall is the only answer that is neither of those.
