CHM211 Quiz - Xirius

1. Why is glycogen more branched than amylopectin?

A. Because it contains α-1,3-glycosidic bonds B. Because of more α-1,6-glycosidic branch points C. Due to β-1,4-glycosidic linkages D. It is less branched

2. Why is sucrose classified as a non-reducing sugar?

A. It contains ketone groups only. B. It has no hemiacetal groups, both sugars are glycosides. C. It cannot form glycosidic linkages. D. It does not hydrolyze in aqueous acid.

3. What functional groups are present in all amino acids?

A. Hydroxyl and carboxyl B. Amino and carboxyl C. Aldehyde and amino D. Ketone and hydroxyl

4. Which of the following is a typical function of globular proteins?

A. Structural support B. Enzymatic catalysis C. Forming connective tissues D. Providing rigidity to plant cell walls

5. Which of the following changes in protein denaturation results in loss of enzymatic activity?

A. Formation of peptide bonds B. Disruption of the active site’s 3D structure C. Increase in hydrophobic interactions D. Secondary structure stabilization

6. What does denaturation NOT affect in a protein?

A. Primary structure B. Secondary structure C. Tertiary structure D. Quaternary structure

7. Which of the following causes denaturation by disrupting ionic bonds and altering side-chain ionization?

A. Organic solvents B. Heat C. Heavy metals D. Extreme pH values

8. Why is starch more digestible in humans compared to cellulose?

A. Because starch contains β-glycosidic bonds B. Because starch contains α-glycosidic bonds C. Because cellulose is soluble in water D. Because cellulose has branched structure

9. What defines a monosaccharide as an aldose sugar?

A. Having a ketone functional group B. Having an aldehyde functional group C. Containing a carboxyl group D. Having no carbonyl groups

10. What type of linkage does cellulose contain between glucose units?

A. α-1,4-glycosidic bonds B. β-1,4-glycosidic bonds C. α-1,6-glycosidic bonds D. β-1,6-glycosidic bonds

11. Why do carbohydrates exhibit a general formula of Cx(H2O)y?

A. They contain only carbon and water molecules B. Because hydrogen and oxygen are in the same ratio as in water C. Due to the presence of water molecules loosely associated D. Because they are hydrates of carbon dioxide

12. Which carbohydrate linkage is responsible for the branching points in amylopectin?

A. α-1,2-glycosidic bonds B. β-1,4-glycosidic bonds C. α-1,6-glycosidic bonds D. β-1,6-glycosidic bonds

13. Which of the following best explains the amphoteric nature of amino acids?

A. Having both acidic and basic side chains B. Ability to form both peptide and disulfide bonds C. Presence of ionizable amino and carboxyl groups that can act as acids or bases D. Their ability to polymerize into proteins

14. How do hydrophobic interactions contribute to protein structure?

A. By exposing nonpolar groups to water B. By clustering nonpolar side chains away from water inside the protein C. By forming peptide bonds D. By disrupting tertiary structure

15. Which statement correctly describes peptides?

A. They always contain more than 100 amino acids B. They consist of long chains of sugars C. They are short chains of amino acids, usually fewer than 50 residues D. They have quaternary structure

16. What type of sugars are glucose and fructose classified as?

A. Both aldohexoses B. Glucose is an aldohexose; fructose is a ketohexose C. Both ketohexoses D. Glucose is a ketohexose; fructose is an aldohexose

17. How can glycosides be hydrolyzed back to monosaccharides?

A. By aqueous acid B. By base only C. By strong oxidizers D. They cannot be hydrolyzed

18. What type of bond links amino acids to form peptides and proteins?

A. Ionic bond B. Hydrogen bond C. Peptide bond D. Disulfide bond

19. What is the isoelectric point (pI) of a protein?

A. The pH at which a protein is most soluble B. The pH at which a protein carries no net charge C. The point where protein denatures D. The temperature optimum for enzyme action

20. What is the main product of oxidation of glucose by nitric acid?

A. Gluconic acid B. Glucaric acid C. Sorbitol D. Methyl glucopyranoside

21. What happens to protein solubility upon denaturation?

A. It increases B. It remains the same C. It decreases, causing aggregation and precipitation D. It becomes infinite

22. What is the main biological role of cellulose?

A. Energy storage in animals B. Structural support in plant cell walls C. Acting as enzymes D. Acting as hormones

23. Which bond connects amino acids in a peptide chain?

A. Hydrogen bond B. Ionic bond C. Peptide bond D. Disulfide bond

24. Which of the following stabilizes the tertiary structure of proteins?

A. Peptide bonds only B. Hydrogen bonds, ionic interactions, hydrophobic interactions, and disulfide bonds C. Only hydrogen bonds D. Only hydrophobic interactions

25. Which of the following statements about sucrose is true?

A. It is a reducing sugar B. It contains a free hemiacetal group C. It is formed by glycosidic linkage between glucose C1 and fructose C2 D. It reduces Fehling’s reagent

26. What is the defining feature of quaternary protein structure?

A. Folding of a single polypeptide chain B. Local folding via hydrogen bonds C. Association of multiple polypeptide chains D. Linear amino acid sequence

27. Which of the following is NOT a cause of protein denaturation?

A. High temperature B. Heavy metals C. High salt concentration strengthening ionic bonds D. Organic solvents

28. Which of the following is a major solvent useful in protein denaturation?

A. Water B. Ethanol C. Glycerol D. Carbon dioxide

29. In the peptide bond formation reaction, what molecule is released?

A. Ammonia B. Carbon dioxide C. Water D. Hydrogen

30. What reaction forms glycosidic linkages in carbohydrates?

A. Hydrolysis B. Condensation with elimination of water C. Oxidation D. Electrophilic substitution

31. When glucose reacts with methanol in acidic conditions, what compound is formed?

A. Glycoside B. Cyanohydrin C. Polyglucose D. Peptide

32. What type of protein is collagen classified as?

A. Globular B. Fibrous C. Simple D. Conjugated

33. Which amino acid side chain classifies as nonpolar?

A. Serine B. Aspartic acid C. Alanine D. Histidine

34. Which level of protein structure describes the overall 3D shape of a single polypeptide stabilized by various interactions?

A. Primary B. Secondary C. Tertiary D. Quaternary

35. What causes protein denaturation?

A. Breaking peptide bonds B. Loss of primary structure C. Disruption of secondary, tertiary, or quaternary structures D. Formation of new peptide bonds

36. What is an example of a conjugated protein?

A. Albumin B. Hemoglobin C. Collagen D. Keratin

37. What property is enhanced in bifunctional compounds compared to monofunctional analogs?

A. Lower melting points B. Lower boiling points C. Higher boiling and melting points due to strong hydrogen bonding D. Less polarity

38. What is the common feature of disaccharides?

A. They contain only monosaccharides linked by hydrogen bonds B. They are two monosaccharides linked via glycosidic bond with loss of water C. They are soluble proteins D. They cannot be hydrolyzed

39. What happens to a protein’s solubility upon denaturation?

A. It increases due to exposure of hydrophobic groups. B. It remains unchanged. C. It decreases as proteins aggregate and precipitate. D. It varies with temperature but not structure.

40. Which factor can denature proteins by binding to thiol groups?

A. Heat B. Extreme pH C. Heavy metals like Hg²⁺ D. Organic solvents

41. Which of the following is a characteristic of globular proteins?

A. They are generally insoluble in water. B. They act primarily as structural components. C. They generally have compact, functional shapes. D. They have elongated fibrous shapes.

42. What is the main difference between peptides and proteins?

A. Peptides are branched; proteins are linear B. Peptides have fewer than 50 amino acids; proteins have more than 50 amino acids C. Peptides have quaternary structure; proteins do not D. Peptides contain only nonpolar amino acids; proteins have polar amino acids

43. Denaturation of proteins affects which of the following?

A. The amino acid sequence B. The peptide bonds C. The secondary, tertiary, and quaternary structures D. Formation of peptide bonds

44. Which of the following compounds is a homobifunctional compound?

A. 2-Chloroethanol B. Oxalic acid C. Ethanolamine D. Methyl glucopyranoside

45. What is the role of glycoproteins as conjugated proteins?

A. Structural support only B. Enzymatic catalysis only C. Cell recognition and signaling D. Energy storage

46. Which amino acid side chain group makes it positively charged at physiological pH?

A. Acidic side chains B. Nonpolar side chains C. Basic side chains D. Polar, uncharged side chains

47. Which polysaccharide serves as the primary energy storage in animals?

A. Cellulose B. Starch C. Glycogen D. Amylose

48. What functional groups are present in amino acids that make them bifunctional compounds?

A. Carboxyl (–COOH) and hydroxyl (–OH) B. Amino (–NH₂) and carboxyl (–COOH) C. Aldehyde (–CHO) and ketone (C=O) D. Hydroxyl (–OH) and aldehyde (–CHO)

49. What level of protein structure describes the linear sequence of amino acids?