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Practice · Biology · 2025 syllabus · A1.2

IB Biology A1.2 Nucleic acids: practice questions

6 exam-style questions on A1.2 Nucleic acids, SL and HL, 1 marked HL: 3 multiple choice, 1 data-based, 1 short answer and 1 extended response. Each one comes with the mark scheme, a model answer and the reasoning behind every mark. Free with your email.

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A1.2-01 · Paper 1A style · multiple choice · 1 mark

Features of messenger RNA

Which features does a molecule of messenger RNA (mRNA) have? [1]

  1. Deoxyribose sugar, the base uracil and a single strand
  2. Ribose sugar, the base thymine and a single strand
  3. Ribose sugar, the base uracil and two antiparallel strands
  4. Ribose sugar, the base uracil and a single strand
Show the answer and the reasoning

Answer: D. RNA nucleotides contain ribose, RNA uses uracil in place of thymine, and mRNA is a single strand. A gives the sugar of DNA. B gives the base found only in DNA. C describes the double-stranded structure of DNA; mRNA is copied from one DNA strand and is single-stranded.

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The 6 questions in A1.2

  1. A1.2-01 Features of messenger RNAPaper 1A style · multiple choice · 1 mark
  2. A1.2-02 Writing the complementary strandPaper 1A style · multiple choice · 1 mark · HL
  3. A1.2-03 Base counts from base pairingPaper 1A style · multiple choice · 1 mark
  4. A1.2-04 Storing and copying informationPaper 2 style · short answer · 8 marks
  5. A1.2-05 Base composition of DNAPaper 1B style · data-based · 9 marks
  6. A1.2-06 Structure and copying of DNAPaper 2 style · extended response · 15 marks

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Every Biology and Chemistry question here is original, written for practice in the style of the papers set since the 2025 syllabus, with invented data. Developed independently from the International Baccalaureate Organization, which has not endorsed it. Found a mistake? Email vytis@limeadmissions.com with the question id.