Identify the correct statement related to amino acids.

Which type of biomolecules have some structural similarity with synthetic polyamides? What is this similarity?

Starting with three different amino acid molecules,how many different tripeptide molecules are formed?

Discuss the structure and shape of proteins.

Treatment of compound $O$ ($1,2-$diethylbenzene) with $KMnO_4 / H^{+}$ gives $P$ (phthalic acid),which on heating with ammonia gives $Q$ (phthalamide). The compound $Q$ on treatment with $Br_2 / NaOH$ produces $R$ ($o-$phenylenediamine). On strong heating,$Q$ gives $S$ (phthalimide),which on further treatment with ethyl $2-$bromopropanoate in the presence of $KOH$ followed by acidification,gives a compound $T$.
$(1)$ The compound $R$ is
$(2)$ The compound $T$ is
$(A)$ glycine
$(B)$ alanine
$(C)$ valine
$(D)$ serine
Identify the correct options for $(1)$ and $(2)$.

The synthetic sweetener aspartame,known commercially as NutraSweet,is a methyl ester of a dipeptide. In aqueous solution on standing,it changes to: