Answer: Nitrogen.
- A Nitrogen
- B Carbon
- C Hydrogen
- D Oxygen
Correct answer: A. Nitrogen
Explanation: Proteins contain nitrogen (in amino groups) in addition to C, H, and O found in all three macromolecules.
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.