Q.Identify the given biomolecules A and B.

The Haworth structure drawn is 2-deoxyribose, the pentose sugar of DNA, identifiable because one of its ring carbons (C2') carries only an H with no OH, unlike ribose where every ring carbon between the CH2OH-bearing carbon and the anomeric carbon carries an OH.

Both ribose and deoxyribose are furanose (5-membered ring) pentose sugars found in nucleic acids: ribose in RNA, deoxyribose in DNA. In the Haworth structure:

• The ring oxygen sits at the top, flanked by two ring carbons.
• The carbon bearing the -CH2OH (the HOH2C group, corresponding to C5') is C4'.
• The carbon on the other side of the ring oxygen, bearing both an OH and an H, is the anomeric carbon, C1'.
• Moving around the ring from C1' to C4', ribose has an -OH group at BOTH C2' and C3'. Deoxyribose, however, has lost the oxygen at C2' (hence '2-deoxy'), so that carbon carries two hydrogens instead, while C3' still retains its OH. …

Of the four named substances, Trypsin and Insulin are proteins, Cholesterol is a lipid, and Adenylic acid is a nucleotide (nucleic-acid building block), matching these correctly by elimination gives option (a).

• Trypsin is a proteolytic digestive enzyme, a protein.
• Insulin is a peptide hormone, also a protein.
• Cholesterol is a steroid, a lipid.
• Adenylic acid (adenosine monophosphate) is a nucleotide, the monomeric unit of nucleic acids like RNA. …