Which proteins serves as a chemical messenger

Neuropeptides

Explanation:

They are proteins that function as chemical messengers and are released by neurons. They contain 3 to 36 amino acids.

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answer: collecting information/data

reason: the student is going around and asking people questions to collect data

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oxygen = 21% of the atmosphere

nitrogen = 78%

carbon dioxide = 0.1%

argon =0.934%