phycical change
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Directional selection, as one phenotype is greatly favored over another
Sympathetic nervous system
These physical reactions are triggered by the sympathetic nervous system.
The sympathetic nervous system is part of the autonomic nervous system that triggers the fight or flight response. The sympathetic nervous system functions through various interconnected neurons in the body and it is responsible for preparing the body for physical and mental activity. The sympathetic nervous system causes the heart to beat faster and stronger, opens the airways for easy breathe, and prevents digestion.
False: large crystals are formed when it cools slowly
