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

Q21. Which of the following vitamins is water-soluble?

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

Answer: (b) Vitamin C

Explanation: Vitamin C (ascorbic acid) is water-soluble and is essential for the synthesis of collagen and wound healing. Water-soluble vitamins are not stored in the body and must be replenished regularly.

Q22. Deficiency of Vitamin D leads to:

(a) Scurvy
(b) Rickets
(c) Pellagra
(d) Beriberi

Answer: (b) Rickets

Explanation: Vitamin D deficiency leads to rickets in children, characterized by the softening and weakening of bones due to impaired calcium absorption.

Q23. Which vitamin is essential for the coagulation of blood?

(a) Vitamin A
(b) Vitamin K
(c) Vitamin D
(d) Vitamin B12

Answer: (b) Vitamin K

Explanation: Vitamin K plays a critical role in the synthesis of proteins required for blood clotting. Its deficiency can lead to bleeding disorders.

Q24. Pellagra is caused due to a deficiency of which vitamin?

(a) Vitamin C
(b) Niacin (Vitamin B3)
(c) Riboflavin (Vitamin B2)
(d) Folic acid

Answer: (b) Niacin (Vitamin B3)

Explanation: Pellagra is a disease caused by a deficiency of niacin, characterized by symptoms such as dermatitis, diarrhea, and dementia.

Q25. Which of the following is a fat-soluble vitamin?

(a) Vitamin B12
(b) Vitamin C
(c) Vitamin E
(d) Vitamin B6

Answer: (c) Vitamin E

Explanation: Vitamin E is a fat-soluble vitamin and an important antioxidant that protects cells from oxidative stress. Fat-soluble vitamins are stored in body fat and are not easily excreted.

Q26. The number of hydrogen bonds between adenine and thymine in a DNA molecule is:

(a) One
(b) Two
(c) Three
(d) Four

Answer: (b) Two

Explanation: Adenine and thymine are paired together in DNA through two hydrogen bonds, while cytosine and guanine form three hydrogen bonds.

Q27. The sugar present in DNA is:

(a) Ribose
(b) Glucose
(c) Fructose
(d) Deoxyribose

Answer: (d) Deoxyribose

Explanation: DNA contains deoxyribose, a five-carbon sugar that lacks an oxygen atom on the second carbon, distinguishing it from ribose, which is found in RNA.

Q28. Which enzyme is responsible for adding new nucleotides during DNA replication?

(a) DNA polymerase
(b) RNA polymerase
(c) Helicase
(d) Ligase

Answer: (a) DNA polymerase

Explanation: DNA polymerase is the enzyme that synthesizes new DNA strands by adding nucleotides to a growing DNA chain during replication.

Q29. Which of the following is an example of a polysaccharide?

(a) Ribose
(b) Maltose
(c) Glycogen
(d) Galactose

Answer: (c) Glycogen

Explanation: Glycogen is a polysaccharide that serves as the primary storage form of glucose in animals. It is stored mainly in the liver and muscle tissues.

Q30. The test used to detect the presence of starch is:

(a) Benedict’s test
(b) Biuret test
(c) Iodine test
(d) Fehling’s test

Answer: (c) Iodine test

Explanation: The iodine test is used to detect the presence of starch. When iodine is added to a starch solution, a blue-black color appears, indicating a positive result.