1A: Amino Acids & Proteins — Application

The carboxyl group is 50% deprotonated, the amino group remains predominantly protonated, and the net charge is approximately $+0.5$.

Both groups are 50% deprotonated, so the net charge is $0$.

The carboxyl group is fully deprotonated and the amino group is fully protonated, so the net charge is $0$.

The carboxyl group remains predominantly protonated, the amino group is 50% deprotonated, and the net charge is approximately $+1$.