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OJEE Genetic Code — practice questions

Explore 6 free Genetic Code questions in OJEE Biology. Open each question or exercise to read its content, reference answers and available explanation.

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Genetic Code questions and exercises with answers

Showing questions 1–6 of 6.

The genetic code is a:Read the answer and worked solution →The **initiation codon** for translation is:Read the answer and worked solution →Which of the following is **not** a stop codon?Read the answer and worked solution →Wobble hypothesis explains:Read the answer and worked solution →Key features of the **genetic code** include all of the following EXCEPT:Read the answer and worked solution →Spot the trait Mendel never usedRead the answer and worked solution →

Worked practice questions

The genetic code is a:

  1. Singlet code (1 base per amino acid)
  2. Doublet code (2 bases per amino acid)
  3. Triplet code (3 bases per amino acid)
  4. Quadruplet code (4 bases per amino acid)
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Correct answer: C. Triplet code (3 bases per amino acid)

**Triplet code:** 4³ = 64 possible codons specify the 20 amino acids (with redundancy/degeneracy). Singlet would give only 4 codes doublet only 16. Crick demonstrated tripletness via frame-shift mutations.

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The **initiation codon** for translation is:

  1. UAA
  2. UAG
  3. UGA
  4. AUG (codes for methionine)
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Correct answer: D. AUG (codes for methionine)

AUG is the universal start codon, coding for methionine (formyl-methionine in prokaryotes). UAA, UAG, UGA are the three stop codons — they don't code for any amino acid and terminate translation.

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Which of the following is **not** a stop codon?

  1. UAA
  2. UAG
  3. UGA
  4. AUG
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Correct answer: D. AUG

AUG is the **start** codon (methionine). UAA (ochre), UAG (amber) and UGA (opal) are the three stop codons that terminate the elongating polypeptide chain.

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