Nucleic acids and their functions: Eduqas A‑Level Biology questions

Every Eduqas A-Level Biology exam question on C.5 Nucleic acids and their functions, 2016–2025, with its mark scheme and examiner’s report.

Find questions2,061

PaperExamSort

Calculations Only these Leave out

2,061 questions

Q3(a)(ii)
June 2025 · Component 2
4 marks2.7 Application of reproduction and genetics C.5 Nucleic acids and their functions
The whole paper ↗
Q5(d)(i)
June 2025 · Component 2
1 markC.5 Nucleic acids and their functions
The whole paper ↗
Q5(d)(ii)
June 2025 · Component 2
1 markC.5 Nucleic acids and their functions
The whole paper ↗
Q5(d)(iii)
June 2025 · Component 2
3 marks2.5 Inheritance C.5 Nucleic acids and their functions
The whole paper ↗
Q5(d)(iv)
June 2025 · Component 2
2 marksC.5 Nucleic acids and their functions
The whole paper ↗
Q5(a)(i)
June 2025 · AS Component 1
1 markC.5 Nucleic acids and their functions
The whole paper ↗
Q5(a)(ii)
June 2025 · AS Component 1
1 markC.5 Nucleic acids and their functions
The whole paper ↗
Q5(b)(i)
June 2025 · AS Component 1
2 marksC.5 Nucleic acids and their functions
The whole paper ↗
Q5(c)
June 2025 · AS Component 1
2 marksC.5 Nucleic acids and their functions
The whole paper ↗
Q5(d)
June 2025 · AS Component 1
2 marksC.5 Nucleic acids and their functions
The whole paper ↗
Q1(a)(i)
June 2024 · Component 1
2 marksC.5 Nucleic acids and their functions
The whole paper ↗
Q1(a)(ii)
June 2024 · Component 1
2 marksC.5 Nucleic acids and their functions
The whole paper ↗
Q1(a)(iii)
June 2024 · Component 1
1 markC.5 Nucleic acids and their functions
The whole paper ↗
Q2(b)(ii)
June 2024 · Component 2
2 marksC.5 Nucleic acids and their functions
The whole paper ↗
Q2(c)(i)
June 2024 · Component 2
1 markC.5 Nucleic acids and their functions
The whole paper ↗
Q2(d)(i)
June 2024 · Component 2
1 markC.5 Nucleic acids and their functions
The whole paper ↗
Q2(d)(ii)
June 2024 · Component 2
3 marks2.1 All organisms are related through their evolutionary history C.5 Nucleic acids and their functions
The whole paper ↗
Q3(a)(ii)
June 2024 · Component 2
1 markC.5 Nucleic acids and their functions
The whole paper ↗
Q6(d)(i)
June 2024 · Component 2
2 marks2.2 Genetic information is copied and passed on to daughter cells C.5 Nucleic acids and their functions
The whole paper ↗
Q6(d)(ii)
June 2024 · Component 2
2 marksC.5 Nucleic acids and their functions
The whole paper ↗

All 105 questions on Nucleic acids and their functions, as a list

June 2025, Component 2, Q3(a)(ii) (4 marks): DNA replication takes place in both human cells and in PCR. State two similarities and two differences between DNA replication in PCR and DNA replication in cel
June 2025, Component 2, Q5(d)(i) (1 mark): Give the DNA sequence which would be complementary to this section of mRNA. [1] Table 5.5 shows mRNA codons and the amino acids coded for by each codon. Table 5
June 2025, Component 2, Q5(d)(ii) (1 mark): Use the mRNA codons provided in Table 5.5 to give the amino acid sequence coded for by the section of mRNA in Image 5.4. [1] Some mutations occur when one nucle
June 2025, Component 2, Q5(d)(iii) (3 marks): Explain how the substitution of a nucleotide may cause a gene to code for a different protein. [3]
June 2025, Component 2, Q5(d)(iv) (2 marks): Some nucleotide substitutions have no effect on the protein coded by the exons of this gene. Use an example from Table 5.5 to explain why. [2]
June 2025, AS Component 1, Q5(a)(i) (1 mark): Complete the DNA sequence that would have acted as the template strand for the mRNA shown in Image 5.1. [1] Coding ATG CCG GCA CGG ATT CTG strand Template stran
June 2025, AS Component 1, Q5(a)(ii) (1 mark): State one feature of the genetic code demonstrated by the base sequences that code for thr (threonine) in Image 5.1. [1]
June 2025, AS Component 1, Q5(b)(i) (2 marks): I. Suggest the nitrogenous base found in GTP. [1] II. Write an equation to show the exergonic reaction in which GTP would release energy. [1]
June 2025, AS Component 1, Q5(c) (2 marks): In MND, a single base substitution in the FUS gene produces a polypeptide chain which is significantly shorter than normal. Suggest how a single base change cou
June 2025, AS Component 1, Q5(d) (2 marks): The FUS gene contains 15 exons, from which several different versions of the FUS protein can be synthesised. Suggest how this is possible and why it might provi
June 2024, Component 1, Q1(a)(i) (2 marks): Draw and label a simple diagram to show the structure of ATP. [2]
June 2024, Component 1, Q1(a)(ii) (2 marks): With reference to the structure of ATP, explain what is meant by the term universal energy currency. [2]
June 2024, Component 1, Q1(a)(iii) (1 mark): State one structural difference between the nucleotides found in DNA compared to those found in an ATP nucleotide. [1]
June 2024, Component 2, Q2(b)(ii) (2 marks): I. With the human and chimpanzee comparison, the amino acid sequence is identical but the base sequence of the intron is different. Mutations in the base sequen
June 2024, Component 2, Q2(c)(i) (1 mark): Calculate the minimum number of nucleotides needed to code for cytochrome c. [1] Minimum number of nucleotides =
June 2024, Component 2, Q2(d)(i) (1 mark): Explain how heating results in single-stranded DNA. [1] Single-stranded DNA from one species is then mixed with single-stranded DNA from another species. These
June 2024, Component 2, Q2(d)(ii) (3 marks): Biologists formed hybrid DNA from a human and a chimpanzee and from a human and an orangutan. Suggest why hybrid human / chimpanzee DNA separated at higher temp
June 2024, Component 2, Q3(a)(ii) (1 mark): State the name of two nucleotides that contain pentose sugar. [1]
June 2024, Component 2, Q6(d)(i) (2 marks): Use the information given and Table 6.2 to explain why grade II tumours would have a higher level of radioactivity than grade I tumours after being removed from
June 2024, Component 2, Q6(d)(ii) (2 marks): Explain why radioactive thymine would be used to measure the rate of mitosis and not radioactive guanine. [2]
June 2024, AS Component 1, Q4(a)(i) (3 marks): Using Images 4.1A, 4.1B and 4.1C, state one similarity between all the molecules shown and two differences in structure between ATP and NAD. [3] Similarity: Dif
June 2024, AS Component 1, Q4(a)(ii) (3 marks): Explain why ATP is a suitable ‘energy currency’ in all living organisms. [3] Question continued overleaf
June 2024, AS Component 1, Q4(b)(i) (1 mark): The 14N would be incorporated into the newly synthesised DNA. State into which part of a DNA nucleotide the 14N would be incorporated. [1]
June 2024, AS Component 1, Q4(b)(ii) (1 mark): Suggest why the generation 0 sample was taken before the 15N labelled cells were added to the 14N culture medium. [1]
June 2024, AS Component 1, Q4(b)(iii) (5 marks): Use your own knowledge and the information in Image 4.2 to explain how the results for the following generations support the theory of semi-conservative replica
June 2024, AS Component 1, Q4(b)(iv) (1 mark): Suggest why the percentage of DNA found at position Y in generation 1 has reduced from 100% to 12% by generation 4 [1]
June 2024, AS Component 1, Q6 (9 marks): Cells of the airway in humans secrete mucus. The thickness of this mucus is regulated by the movement of chloride ions through an intrinsic membrane protein cal
June 2023, Component 2, Q5(a)(i) (2 marks): State two differences between nucleotides of RNA and nucleotides of DNA. [2]
June 2023, Component 2, Q5(b)(i) (3 marks): Calculate the length of DNA in the nucleus of the cell from a male with DMD in millimetres (mm). Give your answer in standard form. Show your working. [3] Len
June 2023, Component 3, Q3(d)(ii) (1 mark): Use Table 3.3 to suggest the minimum number of genes that are involved in the production of haemoglobin. [1]
June 2023, Component 3, Q7(b)(iii) (3 marks): Rifampicin works by inhibiting bacterial RNA polymerase enzyme, preventing transcription from taking place. Explain how rifampicin would affect M. tuberculosis.
June 2023, AS Component 1, Q4(a) (2 marks): The genetic material within the SARS virus is RNA. State two ways in which the structure of RNA differs from DNA. [2]
June 2023, AS Component 1, Q4(b)(i) (1 mark): Part of the viral RNA is shown below. Write the sequence of bases for the complementary mRNA molecule formed from the viral RNA. [1] Viral RNA A U G G C C A G U
June 2023, AS Component 1, Q4(b)(ii) (5 marks): Using your own knowledge of protein synthesis suggest how the host cell uses the mRNA to produce viral membrane protein M. [5]
June 2022, Component 1, Q2(a)(i) (2 marks): Name the three biochemical components found in both ATP and NAD. [2]
June 2022, Component 1, Q2(a)(ii) (1 mark): State how one biochemical component of a nucleotide found in DNA would differ from both of the molecules shown in Image 2.1. [1]
June 2022, Component 2, Q5(a)(ii) (3 marks): The bases labelled X and Y could form a complementary base pair. Both bases are found in DNA and RNA. Deduce the identity of these bases giving reasons for your
June 2022, Component 2, Q5(b)(i) (1 mark): State the difference between the two nucleotides shown in Image 5.2. [1]
June 2022, Component 2, Q5(b)(ii) (1 mark): Explain why the addition of a dideoxyribonucleotide to the end of a DNA strand prevents further bases being added to the chain. [1]
June 2022, Component 3, Q1(a) (1 mark): State the minimum number of nucleotides on the DNA strand coding for melittin. [1]
June 2022, AS Component 1, Q5(a)(i) (3 marks): State three differences between the DNA of the human papillomavirus and the nuclear DNA of the host cell. [3] Human papillomavirus DNA Host cell nuclear DNA
June 2022, AS Component 1, Q5(b)(ii) (4 marks): Using your knowledge of DNA replication, describe the process by which the viral DNA is replicated. [4]
June 2022, AS Component 1, Q5(b)(iii) (1 mark): Explain why the viral DNA cannot be replicated outside the nucleus of the host cell. [1]
June 2022, AS Component 1, Q5(b)(iv) (1 mark): The viral genome contains eight genes and therefore codes for a minimum of eight polypeptides. State the name of the hypothesis represented by this statement. [
Autumn 2021, Component 1, Q3(d)(ii) (2 marks): Use the information given and your knowledge of protein synthesis to explain why the sweetness of the tomatoes will not increase after they have been stored at
Autumn 2021, Component 2, Q2(b) (3 marks): The point labelled LUCA on the diagram stands for Last Universal Common Ancestor. Suggest how the role of ATP provides evidence that all organisms have evolved
Autumn 2021, Component 2, Q6(a)(i) (1 mark): Name processes X and Y involved in the production of polypeptides 1, 2 and 3. [1] X Y
Autumn 2021, Component 2, Q6(a)(ii) (1 mark): Explain how the information shown in image 6.1 disproves the ‘one gene – one polypeptide’ hypothesis. [1]
Autumn 2021, Component 2, Q6(a)(iii) (1 mark): Explain why a mutation in an exon might not affect the primary structure of a protein. [1]
Autumn 2021, Component 2, Q6(b) (5 marks): Muscular dystrophy is caused by mutations to the gene coding for dystrophin which is found in the cell membranes of muscle cells. The dystrophin gene is the lar
Autumn 2021, Component 2, Q6(c)(i) (1 mark): Suggest why the mRNA produced does not contain exon 51 even though the mutation is in exon 50. [1]
Autumn 2021, Component 3, Q7(c)(ii) (3 marks): Use image 7.4 and your own knowledge to explain how tetracycline would prevent the synthesis of cholera toxin (CT). [3]
Autumn 2021, AS Component 1, Q2(a)(i) (1 mark): Draw a ring around one nucleotide. [1]
Autumn 2021, AS Component 1, Q2(a)(ii) (3 marks): Each turn of the double helix contains 10 pairs of bases. A one metre length of DNA has 2.94 × 108 turns. Calculate the distance between two adjacent bases as s
Autumn 2021, AS Component 1, Q2(b)(i) (1 mark): Using the data from table 2.2 explain why the genetic code is described as degenerate. [1]
Autumn 2021, AS Component 1, Q2(b)(ii) (2 marks): A section of bases in an mRNA molecule is shown in table 2.3. Use table 2.2 to complete table 2.3 to show: I. the base sequence of the DNA template from which t
Autumn 2021, AS Component 1, Q2(b)(iii) (2 marks): A change in the order of bases in the genetic code is known as a mutation. In the following example a change in a single base in the code is shown. Original mRN
Autumn 2021, AS Component 1, Q2(c)(i) (2 marks): Name structures X and Y. [2] X Y
Autumn 2021, AS Component 1, Q2(c)(ii) (5 marks): Name and describe the process shown in image 2.4. [5]
Autumn 2020, Component 1, Q2(a)(ii) (2 marks): State two features of the genetic code. [2]
Autumn 2020, Component 1, Q2(a)(iii) (1 mark): State how many genes code for the polypeptides found in a RuBisCO molecule. [1]
Autumn 2020, Component 1, Q3(a) (2 marks): Metabolism is a combination of anabolic reactions which build up molecules and catabolic reactions which break them down. Give one example where ATP is used in:
Autumn 2020, Component 2, Q2(c) (2 marks): During the cell cycle, DNA has been shown to replicate semi-conservatively. Meselson and Stahl were the first scientists to prove this experimentally. In their
Autumn 2020, Component 2, Q3(b)(i) (1 mark): Using only the information given, suggest why strawberries are often used as a source of DNA for extraction in a school setting. [1]
Autumn 2020, Component 2, Q3(b)(ii) (1 mark): Coffee filter paper has a pore size of approximately 20 µm. Suggest why coffee filter paper is used rather than Grade 1 laboratory filter paper with a pore size
Autumn 2020, Component 2, Q4(c)(i) (1 mark): State what is meant by an intron. [1]
Autumn 2020, Component 2, Q4(c)(ii) (2 marks): Explain how post transcriptional modification of mRNA (splicing) in eukaryotic cells provides evidence against the ‘one gene one polypeptide’ hypothesis. [2]
Autumn 2020, AS Component 1, Q4(b)(i) (2 marks): Name the complementary base pairs found in DNA and state the bond that joins them. [2]
Autumn 2020, AS Component 1, Q4(b)(ii) (2 marks): Each complete 360° turn of the double helix of DNA is 34 nm long and contains 10 base pairs. The length of a DNA fragment is 6800 nm. Calculate the number of ba
Autumn 2020, AS Component 1, Q4(b)(iii) (4 marks): With reference to the hydrolysis of DNA, explain why the process of apoptosis would prevent the formation of functional proteins. [4]
June 2019, Component 2, Q2(a) (2 marks): Describe three ways in which a DNA molecule differs from an RNA molecule. [2] The CRISPR technique can be used to remove a target gene. In this technique: • Gui
June 2019, AS Component 1, Q1(a)(i) (1 mark): Identify the type of nitrogenous base found in all three molecules. [1]
June 2019, AS Component 1, Q1(a)(ii) (3 marks): Explain why molecule C is sometimes referred to as the universal energy currency. Include reference to the structure of the molecule in your answer. [3]
June 2019, AS Component 1, Q1(a)(iii) (2 marks): Name the region of molecule C labelled X on the diagram. Use this information to identify the base found in molecule B. [2] X Base in molecule B
June 2019, AS Component 1, Q1(b)(i) (1 mark): Name two organelles which synthesise molecule C. [1]
June 2019, AS Component 1, Q1(b)(ii) (1 mark): State whether the synthesis of molecule C is endergonic or exergonic. Explain your answer. [1]
June 2019, AS Component 1, Q1(b)(iii) (1 mark): The removal of all three phosphate groups from molecule C one after the other would release a total of 75.4 kJ mol−1 of energy. Assuming the removal of the firs
June 2019, AS Component 1, Q4(a) (1 mark): Use some of the letters from the diagram to identify the following molecules involved in protein synthesis. [1] mRNA tRNA rRNA
June 2019, AS Component 1, Q4(b)(i) (2 marks): The structures labelled X and Y on the diagram are sequences of bases. Complete the table below. [2] Name of the Bases in the Base Sequence sequence sequence X
June 2019, AS Component 1, Q4(b)(ii) (3 marks): Describe and explain how a change in the base sequence of X could affect the primary structure of molecule Z. [3]
June 2019, AS Component 1, Q4(c) (2 marks): It was originally proposed that one gene carried the code for one enzyme. This was revised to become the one gene – one protein hypothesis. It is now known as,
June 2019, AS Component 1, Q4(d) (3 marks): Describe the process of transcription. [3]
June 2019, AS Component 1, Q4(e)(i) (1 mark): State the names given to the: [1] coding regions non-coding regions
June 2019, AS Component 1, Q4(e)(ii) (3 marks): With reference to the gene shown in the diagram and your own knowledge of protein synthesis, explain how different proteins can be produced from a single gene.
June 2018, Component 1, Q1(a) (2 marks): Draw a simple, fully labelled diagram of ATP. [2]
June 2018, AS Component 1, Q3(a)(i) (1 mark): Name the organelle that would contain the greatest percentage of RNA. Explain your answer. [1]
June 2018, AS Component 1, Q3(a)(ii) (3 marks): The total mass of RNA in a typical rabbit cell contains about 50 000 000 000 nucleotides. Calculate the approximate number of nucleotides contained in the tRNA
June 2018, AS Component 1, Q3(a)(iii) (3 marks): Explain why there would be large numbers of different mRNA molecules in a rabbit cell but only a maximum of 64 different tRNA molecules. [3]
June 2018, AS Component 1, Q3(b) (2 marks): During translation amino acids can be joined together in different sequences. The drawings below show the structural formulae of the amino acids methionine and
June 2018, AS Component 1, Q5(c)(i) (2 marks): The cytoplasm of Chlamydomonas was found to contain an enzyme that partially digests the chromosomes. Explain how the presence of this enzyme could be a reason
June 2018, AS Component 1, Q5(c)(ii) (3 marks): To improve the quality of data obtained using this method, the scientists added an inhibitor of the enzyme that digests the chromosomes of Chlamydomonas. Sugges
June 2018, AS Component 1, Q6 (9 marks): In 1958, Matthew Meselson and Franklin Stahl conducted a series of experiments that demonstrated that DNA replication is semi-conservative. The images below sho
June 2017, Component 2, Q4(c)(ii) (2 marks): Name the processes labelled x and y on the diagram above. [2] x y The addition of methyl groups to DNA molecules (methylation) is known to interfere with the ab
June 2017, AS Component 1, Q5(a)(ii) (1 mark): Explain why DNase 1 is called an endonuclease. [1]
June 2017, AS Component 1, Q5(a)(iii) (3 marks): The diagram shows a short length of single stranded DNA that was mixed with a sample of the enzyme DNase 1. 5’ A G A T A T G G A C G T A A 3’ Identify the fragm
June 2016, AS Component 1, Q1(a)(i) (1 mark): Identify components A, B and C. [1] A B C
June 2016, AS Component 1, Q1(a)(ii) (3 marks): With reference to components A and B shown above, describe the composition of the nucleotides of DNA, RNA and ATP. [3] DNA RNA ATP
June 2016, AS Component 1, Q6(a) (3 marks): Explain the process of transcription including the roles of the enzymes involved. [3]
June 2016, AS Component 1, Q6(b)(i) (2 marks): Explain why it is important that the RNA which is finally translated, consists only of exons. [2]
June 2016, AS Component 1, Q6(b)(ii) (2 marks): Explain how a change in the sequence of bases in the DNA of the gene (a mutation) would affect the protein produced if it was in I. an intron; [1] II. an exon.
June 2016, AS Component 1, Q6(c)(i) (1 mark): The following figures show the mRNA transcribed from two short lengths of DNA. Using the information following, complete the correct sequence of amino acids for
June 2016, AS Component 1, Q6(c)(ii) (1 mark): Explain why the change of bases shown is described as a silent mutation. [1] Chargaff carried out work examining the ratios of different bases in samples of DNA
June 2016, AS Component 1, Q6(d)(i) (2 marks): Calculate the exact ratio to two decimal places of adenine to thymine and guanine to cytosine for human sperm. [2] adenine to thymine ratio = guanine to cytosin
June 2016, AS Component 1, Q6(d)(ii) (4 marks): Evaluate how closely the suggestions by Pauling and Franklin, shown in the boxes above and opposite, match the current understanding of the arrangement of nucle
June 2016, AS Component 2, Q2(c) (2 marks): Cytochrome oxidase is an enzyme found in mitochondria. It has a quaternary structure. The gene for one polypeptide chain in cytochrome oxidase has 1542 nucleoti

Questions, mark schemes and examiner’s reports are © WJEC Eduqas, from their published past papers. Plumi isn’t affiliated with any exam board. Want whole papers? Every Eduqas A-Level Biology paper.

Rather write your answers by hand on iPad? Plumi marks them against the same mark schemes.