Answer: Cannot be made in the body and come from diet.
- A Are synthesised in the body in excess
- B Cannot be made in the body and come from diet
- C Contain a sulphur atom in the side chain
- D Are optically inactive in aqueous solution
Correct answer: B. Cannot be made in the body and come from diet
Explanation: Essential amino acids cannot be synthesised by the human body and must be supplied through the diet, unlike non-essential amino acids.
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.