Which amino acid would, when incorporated into a polypeptide chain (not at the n or c terminus), make the charge of the polypeptide more positive?

Arginine.

Explanation: Arginine is an amino acid that is used for the biosynthesis of protein. It is made up of an α-amino group, an α-carboxylic acid group, & a side chain consisting of a 3-carbon aliphatic straight chain ending in a guanidino group. At physiological pH, the carboxylic acid is deprotonated (−COO−), the amino group is protonated (−NH3+), and the guanidino group is also protonated to give the guanidinium form (-C-(NH2)2+), making arginine a charged, aliphatic amino acid.

c. because step up transformer steps up the input voltage i.e increases the input voltage  

the number of turns are greater on the secondary side of step up transformer  

transformer does not handle dc current

practical process described pest part of scientific investigation.

because practical knowledge is powerful then therotical knowledge.