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CAIE A Level Biology 9700

Nucleic acids and protein synthesis questions

Exam-style questions on Nucleic acids and protein synthesis, ordered from foundation to challenge. Pick one, write your answer the way you would in the exam, and it comes back marked against the mark scheme, point by point.

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Written by Markquill to follow the Cambridge International syllabus. Markquill is independent and is not affiliated with or endorsed by Cambridge International.

  1. Explain5 marksStandardThe gene FGL1 in the fungus Mycena lucida codes for a polypeptide that is part of an enzyme responsible for producing a fluorescent pigment. The wild-type enzyme functions normally. Two different mutations in the FGL1…
  2. Describe4 marksStandardThe table shows the percentage of each nitrogenous base in a sample of DNA from a fungal species. Base Percentage Adenine 31.0 Thymine 31.0 Guanine 19.0 Cytosine 19.0 Describe the structure of DNA, using the base…
  3. Explain5 marksStandardA scientist compares the DNA of two bacterial species. Species X lives in a hot spring at 70°C, while species Y lives in a temperate lake at 20°C. The scientist finds that the DNA of species X has a higher proportion…
  4. Outline4 marksStandardDuring translation in a eukaryotic cell, amino acids are delivered to the ribosome by tRNA molecules. Outline the roles of transfer RNA (tRNA) and anticodons in this process.
  5. Outline4 marksStandardIn a eukaryotic cell, DNA replication occurs during the S phase of the cell cycle. Outline the roles of DNA polymerase and DNA ligase in this process.
  6. Explain4 marksStandardA laboratory assistant is asked to identify whether a sample contains DNA nucleotides or ATP molecules. Explain two similarities and two differences in the structure of a DNA nucleotide and an ATP molecule that could…
  7. Explain4 marksStandardA molecular biologist is explaining the structural features of nucleotides to a class. She states that both DNA nucleotides and ATP molecules are considered nucleotides. With reference to the components of these…
  8. Describe5 marksStandardA eukaryotic gene contains both exons and introns. Describe the events that occur in the nucleus to produce a mature mRNA molecule from this gene, and explain why the removal of introns is essential before translation.
  9. Outline4 marksStandardIn a eukaryotic cell, DNA replication occurs during the S phase of the cell cycle. Outline the roles of DNA polymerase and DNA ligase in this process, explaining why the lagging strand is synthesised discontinuously.
  10. Explain5 marksStandardPart of the coding strand (non-template strand) of a bacterial gene is shown below. The start codon is ATG and the sequence is read from left to right. Normal: 5' – ATG GCA TCG TAA – 3' Two mutant versions of this gene…
  11. Outline5 marksStandardGene expression involves transcription followed by translation. Outline the key differences between transcription and translation. In your answer, you should refer to the following: location in the cell, the template…
  12. Describe4 marksStandardThe following is the sequence of a mature mRNA molecule from a eukaryotic cell: 5' – AUG GCA UUU GAU UGA – 3' The table below shows the amino acids coded for by some mRNA codons. mRNA Codon Amino Acid AUG Met (start)…
  13. Explain5 marksStandardA short section of the coding (non-template) strand of a gene has the base sequence: ATG GGT TAC CTA The mRNA transcribed from this gene is translated to produce a polypeptide. Two different mutations occur in this…
  14. Outline5 marksStandardA gene in a eukaryotic cell codes for an enzyme. Outline the differences between transcription and translation in the production of this enzyme. In your answer, include the location, template, enzymes involved…
  15. Describe5 marksStandardA eukaryotic gene contains both introns and exons. The gene is transcribed to produce a primary transcript (pre-mRNA). Describe the modifications that occur to this primary transcript to form mature mRNA, and explain…
  16. Describe5 marksStandardDuring DNA replication in a bacterial cell, the two strands of the double helix are replicated differently. Describe the process of semi-conservative replication, explaining why one new strand (the leading strand) is…
  17. Describe5 marksStandardDescribe how the antiparallel structure of DNA and the direction of nucleotide addition by DNA polymerase result in one strand being replicated continuously and the other being replicated in fragments. Include the role…
  18. Outline5 marksStandardIn eukaryotic cells, the process of protein synthesis involves transcription followed by translation. Outline five key differences between transcription and translation. Your answer should include reference to…
  19. Describe5 marksStandardDescribe how DNA is replicated during the S phase of the cell cycle, explaining why one strand is synthesised continuously and the other strand is synthesised in fragments.
  20. Describe4 marksStandardThe following is a short mRNA sequence that is translated in a eukaryotic cell: 5'-AUG GGU UAA-3' A codon table for some of the codons is provided below: Codon Amino acid AUG Methionine (start) GGU Glycine GGC Glycine…
  21. Outline5 marksStandardA DNA replication fork has the following features: Two parental DNA strands: Strand X (running 3' to 5' towards the fork) and Strand Y (running 5' to 3' towards the fork). Newly synthesized strands: a continuous…
  22. Explain4 marksStandardThe table below shows a short sequence from a eukaryotic gene. The top strand is the non-template strand. Strand Sequence (5' to 3') Non-template ATG GCT CGA TAA Template TAC CGA GCT ATT Note: The sequence shown is…
  23. Explain4 marksStandardA DNA nucleotide that contains the base adenine is shown below. (Structural formulae are not required.) Explain two similarities and two differences between the structure of this DNA nucleotide and the structure of an…
  24. Outline5 marksStandardA researcher studied DNA replication in bacteria. Bacteria were grown in a medium containing heavy nitrogen (¹⁵N) for many generations so that all DNA contained ¹⁵N. They were then transferred to a medium containing…
  25. Outline4 marksStandardIn the semi-conservative replication of a DNA double helix, two key enzymes are DNA polymerase and DNA ligase. Outline the distinct roles of these enzymes during replication, and explain how the directionality of DNA…
  26. Outline5 marksStandardA student's diagram of DNA replication at a single replication fork shows the two parental strands (A and B) separating. On strand A, a single new strand (X) is being synthesized continuously towards the fork. On…
  27. Explain5 marksStandardA student compares DNA from two bacterial species. Species A has a GC content of 70%, while Species B has a GC content of 40%. The student finds that the DNA from Species A denatures at a significantly higher…
  28. Describe4 marksStandardThe table shows the base composition of a DNA sample from a marine bacterium. Base Percentage (%) Adenine 31 Guanine 19 Cytosine 19 Thymine 31 Describe how the structure of DNA allows complementary base pairing and how…
  29. Outline4 marksStandardA gene coding for the human insulin polypeptide is being translated in a pancreatic beta cell. Outline the roles of tRNA and anticodons in this process.
  30. Explain4 marksStandardStrand A: 5'-ATGCGTACGTAGC-3' Strand B: 3'-TACGCATGCATCG-5' These are the two strands of a short eukaryotic gene. The gene also contains an intron that is removed during post-transcriptional modification. Explain how…
  31. Describe5 marksStandardIn eukaryotic cells, a gene's primary transcript (pre-mRNA) contains both introns and exons. Describe the process by which the primary transcript is modified to produce mature mRNA, and explain why this modification is…
  32. Explain6 marksChallengeA gene in a bacterium has the following coding (non-template) strand sequence: 5'-ATG GCT CAA TAC GGT-3' In one mutant, a substitution mutation changes the sixth base (counting from the 5' end) from T to A. In another…
  33. Outline7 marksChallengeA eukaryotic cell contains a gene that codes for a digestive enzyme. Outline the processes of transcription and translation of this gene, describing the roles of the template strand, RNA polymerase, mRNA splicing…
  34. Describe5 marksChallengeIn a eukaryotic organism, a gene contains four exons and three introns. The primary transcript of this gene is produced in the nucleus. Describe how the primary transcript is modified to form mature mRNA and explain…
  35. Describe5 marksChallengeThe following is an mRNA sequence from a eukaryotic gene: 5'- AUG GCU UAC CGA UAA -3' A partial mRNA codon table is shown: Codon Amino acid AUG Met (start) GCU Ala GCG Ala UAC Tyr CGA Arg UAA stop Three separate…
  36. Explain6 marksChallengeThe coding strand of a short bacterial gene is 5'-ATG GCT CAG TGA-3'. (a) Explain how this DNA sequence is used to produce a polypeptide. (b) A mutation deletes the fourth base (counting from the 5' end) of this coding…
  37. Describe5 marksChallengeIn a prokaryotic cell, a new round of DNA replication begins at a single origin. As the replication fork moves, one newly synthesised strand is produced continuously, while the other is made in short fragments…
  38. Outline7 marksChallengeA eukaryotic gene codes for a digestive enzyme. (a) Outline the differences between transcription and translation in a eukaryotic cell by constructing a table with the following features: cellular location template…
  39. Explain6 marksChallengeIn terms of hydrogen bonding, explain why the C-G base pair is stronger than the A-T base pair. Then, describe how this difference influences the process of semi-conservative replication, including the roles of DNA…
  40. Describe5 marksChallengeThe table shows the base composition of a DNA template strand and the mRNA transcribed from it. The percentages of adenine, guanine, and thymine in the DNA are given, and the percentages of cytosine and uracil in the…
  41. Explain6 marksChallengeExplain the similarities and differences between the structure of a DNA nucleotide that contains adenine and an ATP molecule. In your answer, refer to the components of each molecule and their roles in the cell.
  42. Explain6 marksChallengeTwo DNA samples, A and B, are isolated from different organisms. Sample A contains 60% C-G base pairs, while sample B contains 40% C-G base pairs. Explain why sample A requires a higher temperature to denature than…
  43. Outline7 marksChallengeIn a eukaryotic gene, the coding strand (non-template strand) contains the following sequence: 5' – ATG GGA TAC CCT – 3' The triplet GGA codes for the amino acid glycine. A substitution mutation changes this triplet to…
  44. Explain6 marksChallengeA bacterial gene encoding a short polypeptide has the following sequence for its coding (non-template) strand: 5' – ATG GCA TTG TGA – 3' This sequence is used in transcription to produce mRNA, which is then translated…
  45. Describe5 marksChallengeA short gene in a eukaryotic cell has the following DNA coding strand sequence (5' to 3'): ATG GCT TAC GGA TAA The mRNA transcribed from this gene is: AUG GCU UAC GGA UAA You are provided with a partial mRNA codon…
  46. Describe5 marksChallengeDuring the S phase of the cell cycle, DNA replication occurs. Describe why one daughter strand (the leading strand) is synthesised continuously while the other (the lagging strand) is synthesised in short fragments. In…
  47. Describe5 marksChallengeThe table shows the percentages of the four bases in a sample of double-stranded DNA isolated from a bacterium. Base Percentage (%) A 28 T 28 C 22 G 22 Describe the structure of DNA and explain how these data support…
  48. Describe5 marksChallengeThe table below shows the percentages of the four nitrogenous bases in a sample of bacterial DNA. Base Percentage Adenine 28 Thymine 28 Guanine 22 Cytosine 22 Describe the structure of DNA, using the data in the table…
  49. Explain6 marksChallengeA short segment of a bacterial gene that codes for a short polypeptide is shown below. The two strands of the DNA double helix are labelled P and Q, with their polarities indicated. Strand P (5' → 3'): ATG GGC CTA TCA…
  50. Explain6 marksChallengeA researcher is studying two species of bacteria. Species X lives in a hot spring at 75°C, while species Y lives in a temperate lake at 20°C. The DNA of species X has a GC content of 72%, whereas species Y has only 42%…
  51. Describe5 marksChallengeA small section of a messenger RNA (mRNA) molecule from a fungus has the base sequence: 5'-AUG GGU UAC UGA-3' The table below shows some mRNA codons and the amino acids they code for (using the universal genetic code)…
  52. Outline7 marksChallengeOutline the process of semi-conservative DNA replication. Explain the roles of DNA polymerase and DNA ligase. Describe the arrangement of bases and bonds in the original DNA molecule that enable it to act as a template.
  53. Outline7 marksChallengeA researcher is investigating DNA replication in a newly discovered eukaryotic cell. Outline the process of semi-conservative DNA replication, explaining the roles of DNA polymerase and DNA ligase. Your answer should…
  54. Outline7 marksChallengeIn a replication fork, parental strand X runs 5' to 3' from left to right; parental strand Y runs 3' to 5'. New strands are synthesized using free nucleotides. One new strand is formed as a continuous length; the other…
  55. Describe5 marksChallengeIn a eukaryotic cell, a gene coding for the protein cytokeratin contains several introns and exons. The primary transcript is synthesised during transcription and then processed in the nucleus before it can be used for…
  56. Outline7 marksChallengeIn a eukaryotic organism, a gene contains the following sequence on the template (transcribed) strand of DNA: Normal gene template: 3'-TAC CGA GGT ACT-5' Mutated gene template: 3'-ATC CGA GGT ACT-5' Outline the process…
  57. Explain6 marksChallengeA student examines models of a deoxyribonucleotide (monomer of DNA) and an ATP molecule. Both contain the nitrogenous base adenine. The DNA nucleotide has deoxyribose and one phosphate group. ATP has ribose and three…