Which behavior is a response to an external stimulus? A. An elephant drinks water to quench its thirst.
B. A dog vomits during an illness to rid itself of pathogens.
C. A child gets a fever to fight off the flu.
D. A turtle suns itself on a rock during a cool day.

You are studying a protein that you call protein x. there is an aspartic acid at a key position in protein x which is important in the folding and stabilization of that protein. if this aspartic acid is changed to a different amino acid, which type of amino acid substitutions is most likely to allow the protein to fold normally?