Hibernation is when an animal hides away during the winter. They stock up with food before hand and sleep all winter. This is a survival tactic.
Cell, Species, and Biosphere is my Answer hope it helps.
Mitochondria is the answer they are the power house
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There are five types of blood vessels: the arteries, which carry the blood away from the heart; the arterioles; the capillaries, where the exchange of water and chemicals between the blood and the tissues occurs; the venules; and the veins, which carry blood from the capillaries back towards the heart.
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