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IB Biology SL D1.2.8 Genetic Code Features Questions

Explore how codon structure and genetic-code features determine the possible amino-acid sequence of a polypeptide in IB Biology SL D1.2.8.

Syllabus
First assessment 2025
Course
Biology SL
Level
SL

Exam points

  • Explain that the genetic code is triplet: each mRNA codon contains three bases and specifies one amino acid, a start signal or a stop signal.
  • Explain degeneracy as multiple codons specifying the same amino acid and explain that the code is almost universal with limited exceptions.
  • Interpret start/stop codons and reading-frame or codon-length representations to relate an mRNA sequence to a polypeptide.

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Study D1.2.8—Genetic code features conceptsOpen the corresponding Concept lesson for explanations, examples and exam connections.

IB Biology SL D1.2.8 Genetic Code Features Questions question 1

[Maximum number: 2]

A short base sequence of mRNA and a table of the genetic code are shown below.
Sequence of mRNA
AUGAGCCGAAGGUAGCUG
Table of the genetic code

Table for Question IB Biology SL D1.2.8 Genetic Code Features Questions question 1 — IB Biology SL

Question (a)

(a)

Outline the function of codons.

[ 1 ]

Question (b)

(b)

Suggest a hypothesis that accounts for the slightly different meaning of some codons in a very limited number of organisms.

[ 1 ]
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