DNA and protein synthesis: Edexcel GCSE Biology questions

Every Edexcel GCSE Biology exam question on DNA and protein synthesis (specification points 3.4–3.10), 2018–2025, with its mark scheme and examiner’s report.

All 71 questions on DNA and protein synthesis, as a list

June 2025, Paper 1 Higher, Q9(c) (6 marks): Explain how DNA is extracted from strawberries. Include in your answer: • the reasons for each stage of the extraction process • the structure of a DNA molecule
June 2025, Paper 1 Foundation, Q2(c)(i) (1 mark): Which type of large molecule is DNA? (1) A monomer B protein C polymer D starch
June 2025, Paper 1 Foundation, Q2(c)(ii) (2 marks): Describe how the bases of a DNA molecule are held together. (2)
June 2025, Paper 1 Foundation, Q4(c)(i) (2 marks): State the purpose of both step 1 and step 2. (2) step 1 step 2
June 2025, Paper 1 Foundation, Q4(c)(ii) (1 mark): State why the cold ethanol was added in step 3. (1)
June 2024, Paper 1 Higher, Q4(c)(i) (1 mark): Which is a definition of a gene? (1) A a section of a DNA molecule that codes for a protein B a section of a chromosome that codes for DNA C the entire DNA of a
June 2024, Paper 1 Higher, Q4(c)(ii) (2 marks): The two strands of a DNA molecule are linked by complementary bases. Describe how the complementary bases are linked in a DNA molecule. (2)
June 2024, Paper 1 Higher, Q5(c) (3 marks): DNA can be extracted from human cells in a similar way to the method used to extract DNA from fruits. Describe the stages of the method used to extract DNA from
June 2024, Paper 1 Higher, Q5(d) (2 marks): The Human Genome Project sequenced the order of the bases in the human genome. Give two other outcomes from the Human Genome Project. (2) 1 2
June 2024, Paper 1 Higher, Q7(b)(i) (4 marks): Describe how mRNA is produced during transcription. (4)
June 2024, Paper 1 Higher, Q7(b)(ii) (1 mark): Name the stage of protein synthesis after transcription. (1)
June 2024, Paper 1 Foundation, Q2(a)(i) (2 marks): Complete the sentences using words from the box. (2) indicator membranes salt substrates sugar vacuoles Crushed strawberries are mixed with washing up liquid an
June 2024, Paper 1 Foundation, Q2(a)(ii) (2 marks): Describe the method shown in stage 2. (2)
June 2024, Paper 1 Foundation, Q2(a)(iii) (1 mark): What is the colour of the DNA precipitate? (1) A blue B orange C white D red
June 2024, Paper 1 Foundation, Q2(b)(i) (1 mark): The range is the difference between the largest value and smallest value in a set of numbers. Which is the range of these results? (1) A 13.2 B 10.4 C 5.9 D 5.3
June 2024, Paper 1 Foundation, Q2(b)(ii) (1 mark): Calculate the mean mass of DNA. (1) mean mass of DNA = ng
June 2024, Paper 1 Foundation, Q10(c)(i) (1 mark): Which is a definition of a gene? (1) A a section of a DNA molecule that codes for a protein B a section of a chromosome that codes for DNA C the entire DNA of a
June 2024, Paper 1 Foundation, Q10(c)(ii) (2 marks): The two strands of a DNA molecule are linked by complementary bases. Describe how the complementary bases are linked in a DNA molecule. (2)
June 2023, Paper 1 Higher, Q7(b) (4 marks): The genetic material of some plant viruses is single-stranded RNA. The RNA is copied by the infected host cell and acts as a mRNA molecule. Describe how protein
June 2023, Paper 1 Higher, Q10(b)(i) (2 marks): Describe how a mutation in the non-coding region of a gene can lead to the production of less protein. (2)
June 2023, Paper 1 Higher, Q10(b)(ii) (1 mark): Which describes the cause of a protein folding incorrectly? (1) A a mutation in the coding region of a gene changes the sequence of the amino acids. B a mutatio
June 2023, Paper 1 Foundation, Q2(b)(ii) (1 mark): Scientists have analysed the genomes of domestic animals. Which is the definition of a genome? (1) A all the cells of an organism B all the enzymes of an organi
June 2022, Paper 1 Higher, Q2(a) (2 marks): DNA molecules contain base pairs. Describe how the base pairs are bonded together in a DNA molecule. (2)
June 2022, Paper 1 Higher, Q2(b)(i) (2 marks): Write the code for the complementary DNA strand in Figure 1. (2)
June 2022, Paper 1 Higher, Q2(b)(ii) (1 mark): Three bases code for each amino acid. Which is the maximum number of amino acids coded for by this strand of DNA? (1) A 3 B 4 C 6 D 12
June 2022, Paper 1 Higher, Q2(b)(iii) (1 mark): What is the shape of a DNA molecule? (1) A triple stranded B single stranded C single helix D double helix
June 2022, Paper 1 Higher, Q2(c)(i) (2 marks): Explain why the enzyme protease was added to the mixture. (2)
June 2022, Paper 1 Higher, Q2(c)(ii) (1 mark): The mixture was then heated and filtered. Finally, the student poured the filtrate into a test tube and ice cold ethanol was poured down the side of the test tu
June 2022, Paper 1 Foundation, Q4(c)(i) (1 mark): State where genes are found in cells. (1)
June 2022, Paper 1 Foundation, Q8(a) (2 marks): DNA molecules contain base pairs. Describe how the base pairs are bonded together in a DNA molecule. (2)
June 2022, Paper 1 Foundation, Q8(b)(i) (2 marks): Write the code for the complementary DNA strand in Figure 16. (2)
June 2022, Paper 1 Foundation, Q8(b)(ii) (1 mark): Three bases code for each amino acid. Which is the maximum number of amino acids coded for by this strand of DNA? (1) A 3 B 4 C 6 D 12
June 2022, Paper 1 Foundation, Q8(b)(iii) (1 mark): What is the shape of a DNA molecule? (1) A triple stranded B single stranded C single helix D double helix
June 2022, Paper 1 Foundation, Q8(c)(i) (2 marks): Explain why the enzyme protease was added to the mixture. (2)
June 2022, Paper 1 Foundation, Q8(c)(ii) (1 mark): The mixture was then heated and filtered. Finally, the student poured the filtrate into a test tube and ice‑cold ethanol was poured down the side of the test tu
June 2022, Paper 1 Foundation, Q8(c)(iii) (2 marks): The student wanted to compare the mass of DNA found in fresh peas with the mass of DNA found in fresh beans. Give two variables the student would need to contro
November 2021, Paper 1 Higher, Q10(a) (3 marks): One gene can have several different alleles. Explain why these alleles can produce proteins with different structures. (3)
November 2020, Paper 1 Higher, Q1(b)(ii) (1 mark): State what is meant by the term genome. (1)
November 2020, Paper 1 Higher, Q5(a)(i) (1 mark): Give the complementary strand sequence for this DNA template. (1) A T G T T A C G T
November 2020, Paper 1 Higher, Q5(a)(ii) (1 mark): Which statement correctly describes a DNA molecule? (1) A two strands joined together by strong bonds to form a double helix B two complementary bases twisted i
November 2020, Paper 1 Higher, Q10(c) (4 marks): One cause of colour blindness is a change in the DNA sequence of a gene. This results in the production of a different protein in cone cells in the retina of th
November 2020, Paper 1 Foundation, Q5(c)(i) (1 mark): What is the correct definition of a genome? (1) A all the cells of an organism B all the enzymes of an organism C all the genetic material of an organism D all
November 2020, Paper 1 Foundation, Q5(c)(ii) (2 marks): A new project called the Earth BioGenome Project aims to discover the sequence of bases in the DNA for all plants and animals. State two benefits of discovering
November 2020, Paper 1 Foundation, Q9(c) (6 marks): DNA is found in the nucleus of cells. Describe the structure of DNA and how it can be extracted from plant cells. . (6)
June 2019, Paper 1 Higher, Q2(b)(i) (1 mark): State why ethanol is used. (1)
June 2019, Paper 1 Higher, Q2(b)(ii) (2 marks): State two variables the student needs to control when using this method to compare the mass of DNA from these two fruits. (2) 1 2
June 2019, Paper 1 Higher, Q2(b)(iii) (1 mark): The student repeated the experiment. Give one reason why. (1)
June 2019, Paper 1 Higher, Q9(a)(i) (1 mark): Which enzyme is involved in the process of transcription? (1) A DNA ligase B lysozyme C RNA polymerase D restriction endonuclease
June 2019, Paper 1 Higher, Q9(a)(ii) (2 marks): Describe how a mutation in the non-coding region of the DNA can prevent a gene being transcribed. (2)
June 2019, Paper 1 Higher, Q9(b) (3 marks): A gene coding for a protein has two alleles. Figure 14 shows the first 5 codons of an mRNA strand for these alleles. Allele 1 – AUG CCA CAG GAG UUC Allele 2 – A
June 2019, Paper 1 Foundation, Q8(a)(i) (1 mark): Which statement about DNA is correct? (1) A each pair of bases is joined by hydrogen bonds B phosphate groups are joined by hydrogen bonds C nucleotides consist
June 2019, Paper 1 Foundation, Q8(a)(ii) (2 marks): Figure 13 shows the percentage of each base in human DNA. 35 30 25 20 percentage in human 15 DNA (%) 10 5 0 A G T C DNA base Figure 13 Describe how this data pr
June 2019, Paper 1 Foundation, Q8(c)(i) (1 mark): State why ethanol is used. (1)
June 2019, Paper 1 Foundation, Q8(c)(ii) (2 marks): State two variables the student needs to control when using this method to compare the mass of DNA from these two fruits. (2) 1 2
June 2019, Paper 1 Foundation, Q8(c)(iii) (1 mark): The student repeated the experiment. Give one reason why. (1)
June 2018, Paper 1 Higher, Q9(b)(i) (1 mark): Structure A is a (1) A base B phosphate C sugar D polymer
June 2018, Paper 1 Higher, Q9(b)(ii) (6 marks): In 2003, the first complete human genome was sequenced. The genomes of different people have small changes in the sequence of the DNA bases. Describe how these
June 2018, Paper 1 Foundation, Q2(a)(i) (1 mark): What is the shape of a DNA molecule? (1) A single helix B double helix C complementary helix D triple helix
June 2018, Paper 1 Foundation, Q2(a)(ii) (1 mark): Which molecules are present in the DNA backbone? (1) A sugars and phosphates B amino acids and bases C sugars and bases D amino acids and phosphates
June 2018, Paper 1 Foundation, Q2(a)(iii) (1 mark): State the type of bond that joins the bases together in the DNA molecule. (1)
June 2018, Paper 1 Foundation, Q2(b) (2 marks): DNA can be extracted from fruit. Describe how cells are broken down to release DNA. (2)
June 2018, Paper 1 Foundation, Q2(c) (2 marks): In 2003, scientists finished sequencing the 3 billion base pairs in the human genome. State two benefits that the Human Genome Project could have for medicine.
Specimen, Paper 1 Higher, Q6(a)(i) (1 mark): Which diagram represents the arrangement of the sugar, phosphate and the base in a DNA nucleotide? (1) key A sugar phosphate B base C D
Specimen, Paper 1 Higher, Q6(a)(ii) (1 mark): An allele starts with the DNA sequence ATGCATGTACCG. Give the sequence of the complementary DNA sequence. (1)
Specimen, Paper 1 Higher, Q6(a)(iii) (2 marks): The length of one DNA nucleotide was measured at 3.3 × 10–10 metres. Calculate the approximate length of a gene containing 250 nucleotides in nanometres. (2) nm
Specimen, Paper 1 Higher, Q10(c) (4 marks): The antigens on pathogens can be proteins with a specific amino acid sequence. Explain how the order of amino acids in a protein is determined by the sequence o
Specimen, Paper 1 Foundation, Q1(c)(i) (1 mark): Which sequence is the complementary DNA strand? (1) A ATGGCTAAGTA B CGTTAGCCTGC C TACCGATTCAT D GCAATGGACG
Specimen, Paper 1 Foundation, Q1(c)(ii) (1 mark): Give one way in which a second allele for eye colour might be different. (1) Figure 3 outlines a method that can be used to extract DNA from fruit. Crush fruit
Specimen, Paper 1 Foundation, Q1(d)(i) (1 mark): Give a reason for filtering the mixture. (1)
Specimen, Paper 1 Foundation, Q1(d)(ii) (1 mark): What is the role of the ethanol? (1) A denature the enzymes B disrupt cell membranes C supercoil the DNA D to precipitate the DNA
Specimen, Paper 1 Foundation, Q5(a)(ii) (2 marks): Humans share 35% of their DNA with a daffodil. The human genome contains 6600 million bases. Calculate the number of bases that are the same as a daffodil. (2)

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