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MCQEasyJEE 2025Proteins (Amino Acids, Structure, Denaturation)

JEE Chemistry 2025 Question with Solution

Identify the essential amino acids from below:

(A) Valine (B) Proline (C) Lysine (D) Threonine (E) Tyrosine

Choose the correct answer from the options given below:

  • A

    (A), (C) and (D) only

  • B

    (A), (C) and (E) only

  • C

    (B), (C) and (E) only

  • D

    (C), (D) and (E) only

Answer

Correct answer:A

Step-by-step solution

Standard Method

Given: We need to identify the essential amino acids from the list: (A) Valine, (B) Proline, (C) Lysine, (D) Threonine, (E) Tyrosine.

Find: Which set contains only essential amino acids.

Essential amino acids are those that cannot be synthesized by the human body and must be obtained through the diet.

From the given list:

  • Valine (A) is an essential amino acid.
  • Proline (B) is a non-essential amino acid.
  • Lysine (C) is an essential amino acid.
  • Threonine (D) is an essential amino acid.
  • Tyrosine (E) is a non-essential amino acid because it can be synthesized from phenylalanine.

Thus, the essential amino acids are (A), (C), and (D) only.

Therefore, the correct option is A.

Stepwise Identification

Given: The amino acids listed are Valine, Proline, Lysine, Threonine, and Tyrosine.

Find: The essential amino acids among them.

Step 1: Recall the definition of essential amino acids. Essential amino acids are those that cannot be synthesized by the human body and must be obtained through diet.

Step 2: Compare each amino acid with the known essential amino acids.

  • Valine – Essential amino acid.
  • Proline – Non-essential amino acid.
  • Lysine – Essential amino acid.
  • Threonine – Essential amino acid.
  • Tyrosine – Non-essential amino acid.

Step 3: Collect only the essential ones. The essential amino acids from the list are Valine, Lysine, and Threonine.

Therefore, the correct answer is (A), (C), and (D) only, so the correct option is A.

Common mistakes

  • Treating Tyrosine as essential is incorrect because it can be synthesized from phenylalanine. Classify it as non-essential here.

  • Including Proline among essential amino acids is incorrect because the human body can synthesize it. Check whether the amino acid must be obtained from diet.

  • Memorizing the term essential without applying the definition leads to errors. Essential amino acids are specifically those that cannot be synthesized by the body.

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