Chemistry MCQ with Answer Explanation : Carbohydrates, Proteins, Vitamins and Nucleic Acid.

Q31. Which of the following sugars is a ketose sugar?

(a) Glucose
(b) Galactose
(c) Fructose
(d) Maltose

Answer: (c) Fructose

Explanation: Fructose is a ketose sugar because it contains a ketone group (-C=O) at the second carbon atom, whereas glucose and galactose are aldoses (containing an aldehyde group).

Proteins MCQs (Continued)
Q32. The bond formed between amino acids in a protein is called:

(a) Hydrogen bond
(b) Peptide bond
(c) Ionic bond
(d) Glycosidic bond

Answer: (b) Peptide bond

Explanation: A peptide bond is a covalent bond formed between the carboxyl group of one amino acid and the amino group of another. It is the key bond linking amino acids in proteins.

Q33. Which of the following proteins is involved in oxygen transport?

(a) Hemoglobin
(b) Collagen
(c) Keratin
(d) Actin

Answer: (a) Hemoglobin

Explanation: Hemoglobin is the oxygen-carrying protein in red blood cells. It binds to oxygen in the lungs and transports it to tissues throughout the body.

Q34. Enzymes are composed of:

(a) Nucleotides
(b) Fatty acids
(c) Proteins
(d) Carbohydrates

Answer: (c) Proteins

Explanation: Most enzymes are proteins. They act as biological catalysts, speeding up chemical reactions in the body without being consumed in the process.

Q35. The primary structure of a protein is stabilized by:

(a) Hydrogen bonds
(b) Peptide bonds
(c) Disulfide bonds
(d) Ionic bonds

Answer: (b) Peptide bonds

Explanation: The primary structure of a protein, which is the sequence of amino acids, is stabilized by peptide bonds between adjacent amino acids.

Q36. An enzyme’s activity is affected by:

(a) Temperature
(b) pH
(c) Substrate concentration
(d) All of the above

Answer: (d) All of the above

Explanation: Enzyme activity can be affected by several factors, including temperature, pH, and substrate concentration. Enzymes have optimal conditions under which they function best.

Q37. Which of the following is not an example of a fibrous protein?

(a) Collagen
(b) Keratin
(c) Elastin
(d) Hemoglobin

Answer: (d) Hemoglobin

Explanation: Hemoglobin is a globular protein, not a fibrous protein. Fibrous proteins, like collagen and keratin, have structural roles, while globular proteins, like hemoglobin, have functional roles such as transport.

Q38. The three-dimensional structure of a protein is maintained by:

(a) Peptide bonds
(b) Disulfide bonds
(c) Ionic interactions
(d) All of the above

Answer: (d) All of the above

Explanation: The three-dimensional structure of a protein (tertiary structure) is maintained by various interactions, including disulfide bonds, ionic interactions, hydrophobic interactions, and hydrogen bonds.

Q39. Which of the following vitamins is synthesized by intestinal bacteria?

(a) Vitamin C
(b) Vitamin K
(c) Vitamin D
(d) Vitamin A

Answer: (b) Vitamin K

Explanation: Vitamin K is synthesized by the gut microbiota and is essential for blood clotting. It is also obtained from green leafy vegetables in the diet.

Q40. Which vitamin is involved in the synthesis of collagen?

(a) Vitamin A
(b) Vitamin C
(c) Vitamin D
(d) Vitamin K

Answer: (b) Vitamin C

Explanation: Vitamin C is crucial for the synthesis of collagen, an important structural protein in connective tissues. It acts as a cofactor for enzymes involved in collagen biosynthesis.