Mutation, inheritance and cystic fibrosis: Edexcel International A Level Biology questions

Every Edexcel International A Level Biology exam question on Mutation, inheritance and cystic fibrosis (specification points 2.14–2.16), 2019–2025, with its mark scheme and examiner’s report.

All 85 questions on Mutation, inheritance and cystic fibrosis, as a list

June 2025, Unit 5, Q8(b) (2 marks): Suggest why the loss of the Y chromosome may lead to higher rates of heart disease in men than women (paragraphs 4 and 5). (2)
June 2025, Unit 5, Q8(g) (1 mark): Calculate the percentage of genes that have been lost from the original Y chromosome (paragraph 15). (1) Answer %
January 2025, AS Unit 1, Q2(a) (2 marks): State what is meant by the term cancer. (2)
January 2025, AS Unit 1, Q8(a) (4 marks): In some types of OI, the collagen is poorly formed and lacks strength. Explain how a substitution mutation could result in collagen that lacks strength. (4)
January 2025, AS Unit 1, Q8(b) (4 marks): In most types of OI the allele responsible for causing the condition is dominant. Determine the probability that a child could inherit OI if one parent has OI a
October 2024, AS Unit 1, Q3(a)(i) (1 mark): Which row of the table shows the genotype and phenotype for individual 1? (1) genotype phenotype A CC unaffected homozygous B Cc unaffected heterozygous C unaff
October 2024, AS Unit 1, Q3(a)(ii) (1 mark): Which allele combinations could individual 3 have? (1) A CC only B cc only C CC or cc D CC or Cc
October 2024, AS Unit 1, Q3(a)(iii) (1 mark): What is the probability that a fourth child would be a female with CMT? (1) A 1 in 2 B 1 in 4 C 1 in 8 D 1 in 16
October 2024, AS Unit 1, Q3(b)(i) (1 mark): In the USA, 5% of people with CMT have one of these dominant forms of the disease. In the USA, there are a total of 126 000 people with all forms of CMT. Calcul
October 2024, AS Unit 1, Q3(b)(ii) (3 marks): An individual with a dominant form of CMT will have the allele combination TT or Tt. Draw a genetic diagram to show the possible allele combinations of the chil
October 2024, AS Unit 1, Q3(c) (2 marks): Another form of CMT can be inherited as a sex‑linked trait on the X chromosome. Explain why a male with CMT cannot pass the disease on to his sons. (2)
October 2024, AS Unit 1, Q7(a)(i) (2 marks): Describe how these types of mutation affect the DNA base sequence of a gene. (2)
October 2024, AS Unit 1, Q7(a)(ii) (4 marks): Explain why these animals can survive with a greater number of substitution mutations than insertion and deletion mutations. (4)
October 2024, AS Unit 1, Q7(a)(iii) (1 mark): Suggest which set of data is the most valid. Give a reason for your answer. (1)
October 2024, AS Unit 1, Q7(b)(i) (2 marks): Calculate the mean mutation rate for the mouse. Draw a line of best fit onto the graph to help you. (2) Answer number of mutations per cell year–1
October 2024, AS Unit 1, Q7(b)(ii) (3 marks): Describe three conclusions that can be made from these graphs. (3) 1 2 3
October 2024, AS Unit 1, Q7(b)(iii) (2 marks): Suggest two reasons for the differences in the number of mutations per cell of these species of animal. (2) 1 2
June 2024, AS Unit 1, Q2(b) (1 mark): Name two types of gene mutation. (1) 1 2
June 2024, AS Unit 1, Q2(c) (2 marks): The graph shows the estimated mutation rate in four groups of primates. 6 Mutation rate / ×10–9 per base pair per year 5 4 1 0 0 5 10 15 20 25 30 Mean age when
June 2024, AS Unit 1, Q5(a) (4 marks): Haemophilia is inherited in a similar way to red-green colour blindness and most people who have it are male. Explain why most people who have haemophilia are m
June 2024, AS Unit 1, Q5(b)(i) (2 marks): Calculate the ratio of people with haemophilia A to those with haemophilia B. Give your answer to two significant figures. (2) Ratio : 1
June 2024, AS Unit 1, Q5(b)(ii) (1 mark): Which is the percentage of the world population who had haemophilia A, in 2021? (1) A 2.35 × 105 B 2.35 × 103 C 2.35 × 10–3 D 2.35 × 10–5
June 2024, AS Unit 1, Q5(b)(iii) (1 mark): The number of people with haemophilia is only an estimate. Give one reason why this is only an estimate. (1)
June 2024, Unit 4, Q5(a) (2 marks): Explain how a cell can become a cancer cell. (2)
January 2024, AS Unit 1, Q7(a) (3 marks): Explain how this mutation results in reduced gas exchange in the lungs. (3)
January 2024, AS Unit 1, Q7(c) (6 marks): One complication of cystic fibrosis is lung disease caused by the build-up of bacteria in the airways. This may be due to the inability of the person to clear m
October 2023, AS Unit 1, Q4(a) (2 marks): Complete the table to show the number of people who are red‑green colour blind in India and the percentage of people who are red‑green colour blind in Malaysia.
October 2023, AS Unit 1, Q4(b)(i) (1 mark): Calculate the ratio of red‑green colour blind males to red‑green colour blind females in Malaysia. (1) Answer
October 2023, AS Unit 1, Q4(b)(ii) (4 marks): Explain why the percentage of red‑green colour blind males is greater than the percentage of red‑green colour blind females. (4)
October 2023, AS Unit 1, Q7(c)(iii) (3 marks): Mutations in the gene coding for the LDL‑R can result in an increased risk of CVD. Explain why mutations in this gene can increase the risk of CVD. (3)
October 2023, Unit 4, Q7(b)(i) (2 marks): Explain how a mutation can result in the formation of a neoantigen. (2)
January 2023, AS Unit 1, Q3(a) (3 marks): Explain why the change in mean FEV1 was used in this investigation. (3)
January 2023, AS Unit 1, Q3(b) (2 marks): Explain why the results of this investigation do not show that this treatment is more effective than using each drug on its own. (2)
January 2023, AS Unit 1, Q3(c) (2 marks): Suggest why a combination of drugs could be more effective in treating people with cystic fibrosis than each drug used on its own. (2)
January 2023, AS Unit 1, Q8(a) (2 marks): Explain why the inheritance of blood type, shown in this diagram, is an example of codominance. (2)
January 2023, AS Unit 1, Q8(b) (4 marks): Determine the ratio of the possible blood type phenotypes of the children of individuals 3 and 4. You must draw a genetic diagram. (4) Genetic diagram: Ratio
January 2023, AS Unit 1, Q8(c)(ii) (6 marks): Discuss the possible effects that a mutation in one of the genes coding for this blood type could have on the phenotype of individual 3. (6)
January 2023, AS Unit 2, Q8(a)(i) (1 mark): It was suggested that this mutant allele arose in meiosis during prophase I. Suggest how this mutant allele could be produced in prophase I. (1)
January 2023, Unit 5, Q4(a)(i) (1 mark): State what is meant by the term mutation. (1)
June 2022, AS Unit 1, Q8(a) (2 marks): Cancer is one of the main causes of death in the world. In 2018, in the UK, there were 541 589 deaths in total and 166 800 of these were due to cancer. Calculat
June 2022, AS Unit 1, Q8(b)(i) (1 mark): Name two other types of mutation. (1) 1 2
June 2022, AS Unit 1, Q8(b)(ii) (1 mark): Estimate the percentage of cancers caused by type 3 substitution mutations. (1) Answer %
June 2022, AS Unit 1, Q8(b)(iii) (4 marks): A type 1 substitution mutation in a gene alters the DNA and mRNA but does not affect the protein synthesised from the mutated gene. Explain how a substitution m
June 2022, AS Unit 1, Q8(c)(i) (1 mark): What is the probability of couple 1 and 2 having a fourth child that is a male affected by PKU? (1) A 0.000 B 0.125 C 0.250 D 0.500
June 2022, AS Unit 1, Q8(c)(ii) (6 marks): Discuss the extent to which this pedigree diagram can be used to identify the genotypes of all the members of this family. (6)
June 2022, Unit 5, Q5(c) (4 marks): Mutations in the genes coding for voltage‑gated calcium ion channels have been linked to neurological conditions. Explain how these mutations might cause these
January 2022, AS Unit 1, Q4(b) (3 marks): Explain how mutations result in cystic fibrosis. (3)
January 2022, AS Unit 1, Q8(a)(ii) (1 mark): Name the type of mutation that causes sickle cell disease. (1)
January 2022, AS Unit 1, Q8(b) (2 marks): In 2020, about 140 million babies were born in the world. About 305 800 babies are born with sickle cell disease each year. Estimate the ratio of babies born wi
January 2022, AS Unit 1, Q8(c)(iii) (1 mark): The lifespan of a red blood cell in a person with sickle cell disease is 11 days. This is 9.17% of the lifespan of a healthy red blood cell. Calculate the lifes
January 2022, AS Unit 1, Q8(c)(iv) (3 marks): Sickle cell disease can result in death. Explain why the changes in the structure of haemoglobin and the shape of the red blood cells could result in death in a
January 2022, Unit 5, Q8(e) (3 marks): Suggest how ES can damage mtDNA (paragraph 7). (3)
October 2021, AS Unit 1, Q1(a) (1 mark): What is a mutation? (1) A a change in the amino acid sequence in DNA B a change in the amino acid sequence in a protein C a change in the base sequence in DNA D
October 2021, AS Unit 1, Q1(b) (1 mark): Name two types of mutation. (1) 1 2
October 2021, AS Unit 1, Q8(a)(i) (3 marks): Gene and allele (3)
October 2021, AS Unit 1, Q8(a)(ii) (3 marks): Genotype and phenotype (3)
October 2021, AS Unit 1, Q8(b) (3 marks): A black chicken was mated with a speckled chicken. They had 25 chicks. Determine the expected number of speckled chicks. You must use a genetic diagram. (3) Ans
October 2021, AS Unit 1, Q8(c)(i) (1 mark): Name the statistics test being used to analyse these data. (1)
October 2021, AS Unit 1, Q8(c)(ii) (2 marks): Complete this table to show the missing values. (2)
October 2021, AS Unit 1, Q8(c)(iii) (1 mark): Calculate E (1) Answer
October 2021, AS Unit 1, Q8(c)(iv) (2 marks): Explain how a critical value table could be used to accept or reject a null hypothesis for this experiment. (2)
June 2021, AS Unit 1, Q4(a) (1 mark): Complete the diagram to show the following information: (1) • individual 7 as a male taster • individual 8 as a male non‑taster • individual 9 as a female taste
June 2021, AS Unit 1, Q4(b)(i) (2 marks): Gene and allele (2)
June 2021, AS Unit 1, Q4(b)(ii) (2 marks): Genotype and phenotype (2)
June 2021, AS Unit 1, Q4(c) (2 marks): Explain which is the dominant allele. Use the information in the pedigree diagram to support your answer. (2)
June 2021, AS Unit 1, Q4(d) (2 marks): Explain why this gene is unlikely to be located on the X chromosome. Use the information in the pedigree diagram to support your answer. (2)
June 2021, AS Unit 1, Q5(a) (3 marks): Explain why a mutation in this gene results in the production of very thick, sticky mucus. (3)
June 2021, AS Unit 1, Q5(b) (5 marks): The diagram shows some health problems associated with cystic fibrosis, in a female. breathing difficulties problems absorbing nutrients infertility Explain why
June 2021, AS Unit 1, Q5(c)(i) (1 mark): Which is the change in concentration of chloride ions in the sweat of an individual when the level of function of CFTR protein decreased from 100% to 18%? (1) A
June 2021, AS Unit 1, Q5(c)(ii) (2 marks): Cystic fibrosis results from different mutations in the CFTR gene. Explain how the graph provides evidence that cystic fibrosis results from different mutations
June 2021, AS Unit 1, Q7(a) (1 mark): Mutations can give rise to cancer. State the meaning of the term mutation. (1)
January 2021, AS Unit 1, Q3(b)(i) (2 marks): Between one in 20 000 and one in 25 000 babies are born with GSD. About 25% of patients with GSD are thought to have Von Gierke disease. In one country, 3.8 mil
January 2021, AS Unit 1, Q3(b)(ii) (2 marks): Von Gierke disease is an inherited disease. Suggest why the majority of these babies are born to parents who are not affected by Von Gierke disease. (2)
January 2021, AS Unit 1, Q8(c) (2 marks): Congenital lactose intolerance (CLI) is an extremely rare genetic disorder. Most people with CLI are found in one country. Suggest why most people with CLI are
January 2021, Unit 5, Q5(a) (3 marks): Explain why mutations in the RPE65 gene can result in blindness. (3)
January 2021, Unit 5, Q8(f) (2 marks): Suggest why the stems of the different versions of haemagglutinin molecules are the same but the heads can be different (paragraph 15). (2)
October 2020, AS Unit 1, Q2(a) (1 mark): The phenotype is affected by the genotype. State what is meant by the term genotype. (1)
October 2020, AS Unit 1, Q2(b) (1 mark): State the probability that the next tiger born to these two parents will be female. (1)
October 2020, AS Unit 1, Q2(c) (3 marks): Determine the expected phenotypic ratio of orange tigers to white tigers born to the parents shown in this pedigree diagram. Use a genetic diagram to support yo
October 2020, AS Unit 1, Q2(d) (1 mark): The incidence of white tigers in the wild is 1 in 10 000 Bengal tigers. There are approximately 6000 Bengal tigers in captivity, 200 of which are white. Calcula
October 2020, AS Unit 1, Q6(b)(ii) (5 marks): Explain the possible effects on a protein if there is a substitution mutation in the 9th base in this DNA strand. Use information in the table to support your a
October 2020, Unit 5, Q8(a) (2 marks): Explain what is meant by the phrase ‘gene variants’ (paragraph 4). (2)
October 2020, Unit 5, Q8(e) (4 marks): Explain how ‘a gene variant that produces a defective form of an enzyme’ reduces the effectiveness of clopidogrel (paragraph 16). (4)
January 2020, AS Unit 1, Q8(a)(i) (2 marks): Calculate the percentage decrease in the diameter of the lumen of the trachea from a person with cystic fibrosis. Take your measurements between X and Y on each
January 2020, AS Unit 1, Q8(a)(ii) (6 marks): Explain why cystic fibrosis causes the differences shown in the diagrams. (6)

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