Answer: Vitamin A.
- A Vitamin C
- B Vitamin D
- C Vitamin K
- D Vitamin A
Correct answer: D. Vitamin A
Explanation: Vitamin A (retinol) is needed for the visual pigment in the eye; its deficiency causes night blindness and xerophthalmia.
Two amino acids join via a condensation reaction: the carboxyl -OH of one and an amine -H of the other are eliminated as water, leaving a peptide bond (-CO-NH-) linking them into a dipeptide; repeating this builds a full protein chain.
Concept context
The chemistry of life: carbohydrates, proteins, lipids, nucleic acids, enzymes, and vitamins. Understand their structures, classification, and biological functions. Highly relevant for NEET and Class 12 board exams.