The answer is Adrenaline
Adrenaline is a stress hormone secreted by the adrenal glands and some other neurons when a person is frightened, excited or generally in stress.
It prepares our body for it's 'fight or flight' mechanism and tightens muscles for exertion.
After a bank robbery, most people feel a rush of adrenaline.
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Answer:
Reproductive cells have half the amount of chromosomes than body cells
Explanation:
I think that you are talking about body cells when you say "most cells in an organism." If that is the case, then the reproductive cells, sperm and egg cells, have half the amount of chromosome than body cells.
For example: Human body cells have 46 chromosomes. Human reproductive cells has 23 chromosomes.
In sexual reproduction, each parent gives 1/2 of a full set of chromosomes to create the full set needed for an organism.