Which body system's main function is to send and receive impulses to direct body activities?

What molecules will be best used to compare different species with the exact same sequence of amino acids? why would two species have the same protein even if the molecules in question is different? (hint: transcription to translation to protein).

Why were the results whit just water so much different than the trials with the detergent ?

Which of the following are responsible for sending messages from the hypothalamus to the thalamus?