Final answer:
In the tripeptide Gly-Ala-Ser, the amino acid at the N-terminal end is Ser. More than one polypeptide chain may be present in a conjugated protein but not in a simple protein. In solution at physiological pH, the side chain of a polar basic amino acid does not bear a negative charge.
Step-by-step explanation:
A tripeptide is a chain consisting of three amino acid units. In the tripeptide Gly-Ala-Ser, the amino acid at the N-terminal end is Ser. This is because the N-terminal end is the end of a peptide or protein whose amino group is free, while the C-terminal end has a free carboxyl group. Therefore, statement (1) is true.
Conjugated proteins can consist of more than one polypeptide chain, while simple proteins consist of only one polypeptide chain. Therefore, statement (2) is true.
In solution at physiological pH, the side chain of a polar basic amino acid does not bear a negative charge. Instead, it is positively charged. Therefore, statement (3) is false.