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

Q81. Which of the following vitamins is water-soluble?

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

Answer: (c) Vitamin C

Explanation: Vitamin C is a water-soluble vitamin that is important for the synthesis of collagen, the immune system, and as an antioxidant. Vitamins A, D, and E are fat-soluble.

Q82. The deficiency of Vitamin D in children leads to:

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

Answer: (d) Rickets

Explanation: Rickets is a condition caused by Vitamin D deficiency in children, leading to soft and weak bones, which can result in skeletal deformities.

Q83. Which of the following is the chemical name of Vitamin B12?

(a) Thiamine
(b) Riboflavin
(c) Cobalamin
(d) Niacin

Answer: (c) Cobalamin

Explanation: Cobalamin is the chemical name of Vitamin B12. It plays a crucial role in red blood cell formation, neurological function, and DNA synthesis.

Q84. Vitamin A is stored in the body mainly in the:

(a) Liver
(b) Kidneys
(c) Skin
(d) Bones

Answer: (a) Liver

Explanation: Vitamin A is primarily stored in the liver, where it can be mobilized as needed for vision, immune function, and cell differentiation.

Q85. Which of the following vitamins helps in the synthesis of nucleic acids and the maturation of red blood cells?

(a) Vitamin D
(b) Vitamin K
(c) Folic acid
(d) Vitamin E

Answer: (c) Folic acid

Explanation: Folic acid (Vitamin B9) is essential for the synthesis of nucleic acids (DNA and RNA) and plays a critical role in the maturation of red blood cells, especially during pregnancy.

Q86. Which of the following is a pyrimidine base found in DNA?

(a) Adenine
(b) Thymine
(c) Guanine
(d) Uracil

Answer: (b) Thymine

Explanation: Thymine is a pyrimidine base found in DNA that pairs with adenine through two hydrogen bonds. Uracil is a pyrimidine found in RNA, replacing thymine.

Q87. The enzyme that catalyzes the synthesis of the RNA primer during DNA replication is:

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

Answer: (b) Primase

Explanation: Primase is the enzyme that synthesizes a short RNA primer, which provides a starting point for DNA polymerase to begin DNA replication.

Q88. The region of a gene where RNA polymerase binds to initiate transcription is called:

(a) Operator
(b) Promoter
(c) Enhancer
(d) Terminator

Answer: (b) Promoter

Explanation: The promoter is a specific DNA sequence located near the start of a gene where RNA polymerase binds to initiate the process of transcription.

Q89. Which of the following is a type of RNA that forms the structural and functional core of the ribosome?

(a) mRNA
(b) tRNA
(c) rRNA
(d) snRNA

Answer: (c) rRNA

Explanation: Ribosomal RNA (rRNA) forms the structural and functional core of ribosomes, which are the sites of protein synthesis in the cell.

Q90. DNA replication is described as:

(a) Conservative
(b) Dispersive
(c) Semiconservative
(d) Non-conservative

Answer: (c) Semiconservative

Explanation: DNA replication is semiconservative because each newly synthesized DNA molecule consists of one original (parental) strand and one new (daughter) strand.