Biomolecules

Q1.In DNA, the base pairs A–T and G–C hold the double helix together. How many hydrogen bonds does each pair form?

• AA–T: 2 H-bonds; G–C: 3 H-bonds
• BA–T: 3 H-bonds; G–C: 2 H-bonds
• CBoth pairs form 2 H-bonds each
• DBoth pairs form 3 H-bonds each

Q2.What is the peptide bond in proteins?

• AA bond between two –NH2 groups of amino acids
• BAn amide bond (–CO–NH–) formed between the –COOH of one amino acid and –NH2 of another
• CA disulfide bond between cysteine residues
• DA hydrogen bond between backbone atoms

Q3.Carbohydrates are chemically defined as:

• ACompounds containing only C, H, and O in a 1:2:1 ratio
• BOptically active polyhydroxy aldehydes or ketones, or compounds that yield such units on hydrolysis
• CHydrates of carbon with general formula Cx(H2O)y only
• DSweet-tasting organic compounds

Q4.In the Haworth projection of sucrose, C-1 of glucose is linked to C-2 of fructose. This is a(n) α,β-1,2-glycosidic bond. This unique linkage makes sucrose:

• AA reducing sugar with free anomeric carbons
• BA non-reducing sugar because both anomeric carbons are used in the glycosidic bond
• CMore reactive than maltose or lactose
• DInsoluble in water

Q5.Which of the following is a polysaccharide?

• ASucrose
• BLactose
• CRibose
• DCellulose