Inheritance: Edexcel International GCSE Biology questions

Every Edexcel International GCSE Biology exam question on Inheritance (specification points 3.14–3.39), 2019–2025, with its mark scheme and examiner’s report.

All 201 questions on Inheritance, as a list

June 2025, Paper 1, Q5(a)(i) (1 mark): State what is meant by the term genome. (1)
June 2025, Paper 1, Q5(a)(ii) (2 marks): Explain the difference between a gene and an allele. (2)
June 2025, Paper 1, Q5(b)(i) (4 marks): Draw a genetic diagram to show the genotypes of the parents, the gametes they can produce and the genotypes and ratio of phenotypes of their possible offspring.
June 2025, Paper 1, Q5(b)(ii) (2 marks): Calculate the probability that the first offspring will be male and have black hair. (2) probability =
June 2025, Paper 1, Q5(c) (3 marks): In horses, eye colour is also controlled by a single gene with two alleles. The dominant allele causes brown eyes and the recessive allele codes for blue eyes.
June 2025, Paper 2, Q1(e)(ii) (3 marks): Read the passage below. Use the information in the passage and your own knowledge to answer the questions that follow. Rivers – the arteries of the world Rivers
June 2025, Paper 2, Q6(b)(i) (2 marks): State two differences between DNA and mRNA. (2) 1 . 2 . .
June 2025, Paper 2, Q6(b)(ii) (4 marks): Explain why these GM apples do not turn brown when the apple tissue is exposed to air. Use your knowledge of protein synthesis to support your answer. (4)
June 2025 (R), Paper 1, Q5(b)(i) (1 mark): Which of these describes the number of chromosomes in the nucleus of a human sperm? (1) A diploid number of 23 chromosomes B diploid number of 46 chromosomes C
June 2025 (R), Paper 1, Q9(a) (1 mark): State what is meant by the term recessive allele. (1)
June 2025 (R), Paper 1, Q9(b)(i) (1 mark): What are the genotypes of individuals 1 and 2? (1) A TT and TT B Tt and TT C tt and Tt D tt and tt
June 2025 (R), Paper 1, Q9(b)(ii) (4 marks): Determine the probability of individuals 3 and 4 having another child that can taste PTC and is male. Use a genetic diagram to show your working. (4) probabilit
June 2025 (R), Paper 1, Q9(c)(i) (4 marks): Explain why there are many people who can taste PTC in areas where there are many poisonous plants. Refer to natural selection in your answer. (4)
June 2025 (R), Paper 1, Q9(c)(ii) (2 marks): People who can taste PTC often find the taste of vegetables very bitter. Suggest why the recessive allele for not tasting PTC still exists in human populations.
June 2025 (R), Paper 2, Q1(g) (2 marks): Read the passage below. Use the information in the passage and your own knowledge to answer the questions that follow. Pollination in fruit trees Plants need to
November 2024, Paper 1, Q6(a) (2 marks): Explain one reason why Drosophila are a popular choice for scientists to use in genetic studies. (2)
November 2024, Paper 1, Q6(b)(i) (4 marks): Draw a genetic diagram to show the genotypes and phenotypes of the parents in the second cross and the ratio of phenotypes and genotypes of their offspring. (4)
November 2024, Paper 1, Q6(b)(ii) (2 marks): Calculate the expected probability of a fly being male and having long wings in this second cross. (2) probability =
November 2024, Paper 1, Q6(b)(iii) (4 marks): The scientists counted the number of male and female offspring with long wings or with short wings from this second cross. The table shows their results. Number
November 2024, Paper 1, Q6(c) (3 marks): Flies with short wings are not found in wild populations of Drosophila. Explain this observation. (3)
June 2024, Paper 1, Q8(a) (1 mark): State what is meant by a recessive allele. (1)
June 2024, Paper 1, Q8(b)(i) (3 marks): Use the pedigree to determine the genotypes of individuals A, B and C. (3) A . B C
June 2024, Paper 1, Q8(b)(ii) (3 marks): Individuals E and F have a third child. Draw a genetic diagram to show the genotypes of E and F, the gametes they produce and the possible genotypes and phenoty
June 2024, Paper 2, Q5(a)(i) (1 mark): Which of these is the complementary sequence of DNA on the other strand of the double helix? (1) A ATG GCA TTA ATA B AUG GCA UUA AUA C CGT TAC GGC CGC D CGU UAC
June 2024, Paper 2, Q5(a)(ii) (1 mark): Which of these is the correct summary of the processes occurring during protein synthesis? (1) A DNA transcription RNA translation protein B DNA translation RNA
June 2024, Paper 2, Q5(b)(i) (1 mark): UUU-AUG-UGU is one combination of codons that codes for the sequence of amino acids W–X–Y. Give the number of other combinations that code for the same amino ac
June 2024, Paper 2, Q5(b)(ii) (3 marks): Explain why most genetic mutations have no effect on the phenotype of an organism. Use the information in the table and your own knowledge in your answer. (3)
June 2024, Paper 2, Q5(b)(iii) (1 mark): State one way that the incidence of mutations can be increased. (1)
June 2024 (R), Paper 1, Q8(a)(i) (4 marks): The diagram shows a family pedigree. Key male with lactose intolerance 1 2 male without lactose intolerance 3 4 5 female with lactose intolerance female without
June 2024 (R), Paper 1, Q8(a)(iii) (4 marks): Milk is a nutritious substance that provides several food groups. In areas of the world where milk is a main part of the diet, fewer people are lactose intolera
June 2024 (R), Paper 2, Q6(a) (1 mark): Give the difference between a gene and a genome. (1)
June 2024 (R), Paper 2, Q6(b) (4 marks): Describe the process of transcription. (4)
June 2024 (R), Paper 2, Q6(c) (3 marks): Explain why a change in the sequence of bases in the DNA does not always result in a change in enzyme function. (3)
June 2024 (R), Paper 2, Q6(d) (2 marks): Some characteristics are determined only by the genes, and some are determined by a combination of the genes and the environment. Give an example of each type o
November 2023, Paper 1, Q5(a) (1 mark): State what is meant by the term allele. (1)
November 2023, Paper 1, Q5(b)(i) (4 marks): Draw a genetic diagram to show the parents, gametes and all possible genotypes and phenotypes of the offspring from cross 3. (4)
November 2023, Paper 1, Q5(b)(ii) (2 marks): Calculate the probability that the first offspring born from cross 3 is a male with short hair. (2) probability =
November 2023, Paper 1, Q5(b)(iii) (2 marks): Some short-haired guinea pigs are homozygous and some short-haired guinea pigs are heterozygous. Explain how a breeder could use a cross to determine the genoty
November 2023, Paper 1, Q5(c) (4 marks): Guinea pigs stay completely still and do not move when they sense danger. Describe how this behaviour has evolved by natural selection. (4)
November 2023, Paper 2, Q4(a) (1 mark): State what is meant by the term mutation. (1)
November 2023, Paper 2, Q4(b) (5 marks): Explain the different effects that a single base mutation can have on transcription and translation and the production and activity of an enzyme. (5)
November 2023, Paper 2, Q4(c)(i) (2 marks): Calculate the mean mutation rate for strain 5207 during meiosis. (2) mean rate = × 108 per division per cell
November 2023, Paper 2, Q4(c)(ii) (1 mark): Suggest why the mutation is calculated per division per cell rather than just per cell. (1)
November 2023, Paper 2, Q4(c)(iii) (4 marks): Comment on the differences in rates of mutation for mitosis and meiosis in the different yeast strains. (4)
June 2023, Paper 1, Q6(a) (3 marks): Use a genetic diagram to show the genotypes of the parent plants, the gametes they produce and the genotypes of the offspring plants. (3)
June 2023, Paper 1, Q6(b)(i) (2 marks): Calculate the ratio of plants with axial flowers to plants with terminal flowers. Give your answer in the form n : 1 (2) ratio = : 1
June 2023, Paper 1, Q6(b)(ii) (3 marks): Explain why the ratio of plants with axial flowers to plants with terminal flowers is different from the expected ratio. (3)
June 2023, Paper 1, Q6(c) (6 marks): Scientists want to discover if plants with axial flowers produce more seeds than plants with terminal flowers. Design an investigation to discover whether plant
June 2023, Paper 1, Q8(d)(ii) (4 marks): Some antibiotics are becoming less effective at controlling bacterial infections. Explain how bacteria have evolved so that antibiotics are less effective. (4)
June 2023, Paper 2, Q1(d)(ii) (4 marks): Read the passage below. Use the information in the passage and your own knowledge to answer the questions that follow. When the Oceans Glow In some areas of the
June 2023, Paper 2, Q6(b)(ii) (1 mark): What term is given to all the DNA in an organism? (1) A gene B genome C genotype D nucleoid
June 2023, Paper 2, Q6(b)(iii) (4 marks): The graph shows the scientists’ results. number of changes in DNA number of different phenotypes Number of Number of changes different in DNA phenotypes per 10
June 2023 (R), Paper 1, Q9(b)(i) (1 mark): Give the possible genotypes of Palmer amaranth plants that are not resistant to herbicides. (1)
June 2023 (R), Paper 1, Q9(b)(ii) (3 marks): A Palmer amaranth plant that is resistant to herbicides is crossed with a Palmer amaranth plant that is heterozygous for herbicide resistance. Draw a genetic di
June 2023 (R), Paper 1, Q9(b)(iii) (1 mark): Give the probability of the cross in (b)(ii) producing a plant that is resistant to herbicide. (1)
June 2023 (R), Paper 1, Q9(b)(iv) (4 marks): Explain how Palmer amaranth plants have evolved to become resistant to herbicides in areas where herbicides are used frequently. (4)
June 2023 (R), Paper 1, Q9(b)(v) (2 marks): In plants such as Palmer amaranth, where the allele for herbicide resistance is recessive, no non-resistant weeds occur after five years of using herbicides. In
June 2023 (R), Paper 2, Q5(a)(i) (2 marks): Complete Diagram 1 by writing the letters of the missing bases in the empty boxes for strand 2. (2)
June 2023 (R), Paper 2, Q5(a)(ii) (1 mark): Give the maximum number of amino acids that are coded for by this DNA strand (strand 2). (1)
June 2023 (R), Paper 2, Q5(a)(iii) (2 marks): The original DNA strand is used to produce mRNA. Complete the empty boxes in Diagram 2 to show the mRNA coded for by this DNA strand. (2) DNA G G C T A G T T G
June 2023 (R), Paper 2, Q5(b) (3 marks): A length of DNA consists of 25 000 base pairs. This makes a total of 50 000 bases. In this length of DNA, 30% of the bases are adenine (A). Determine the number
June 2023 (R), Paper 2, Q5(c) (4 marks): Describe the differences between the process of transcription and the process of translation. (4)
January 2023, Paper 1, Q4(a) (3 marks): Calculate the difference between the percentage of moths that are dark‑coloured in 1992 and the percentage of moths that are dark‑coloured in 1998. (3) differen
January 2023, Paper 1, Q4(b)(i) (5 marks): Plot a line graph to show the number of light‑coloured moths and the number of dark‑coloured moths from 1992 to 1998. Use a ruler to join the points with straig
January 2023, Paper 1, Q4(b)(ii) (5 marks): In the 1990s, many cities introduced laws that prevented the burning of coal. Comment on the changes in the number of light‑coloured moths and the number of dar
January 2023, Paper 1, Q5(a)(i) (2 marks): Explain why a red blood cell cannot be used to show a karyotype. (2)
January 2023, Paper 1, Q5(a)(ii) (1 mark): State the type of cell division that occurs in white blood cells. (1)
January 2023, Paper 1, Q5(a)(iii) (1 mark): The karyotype in diagram 1 is from a male. State how this can be deduced from the diagram. (1)
January 2023, Paper 1, Q5(b)(i) (4 marks): Comment on the differences between the karyotypes shown in diagram 1 and diagram 2 and the effects Turner syndrome will have on the person. Use information from
January 2023, Paper 1, Q5(b)(ii) (1 mark): Suggest how the difference in the chromosomes of people with Turner syndrome may have been produced. (1)
January 2023, Paper 1, Q7(c) (3 marks): Wild dogs hunt a variety of prey species. They usually eat the weak and sick animals. Explain how this behaviour may benefit the species the dogs hunt. (3)
January 2023, Paper 2, Q3(a) (1 mark): State what is meant by the term gene. (1)
January 2023, Paper 2, Q3(b)(i) (1 mark): Complete the table by giving the genotypes of red cattle, white cattle, and roan cattle. (1) Cattle hair colour Genotype red white roan
January 2023, Paper 2, Q3(b)(ii) (4 marks): Two roan‑coloured cattle are mated. Determine the probability that the calf produced is a male calf with roan‑coloured hair. Include a genetic diagram in your a
January 2023, Paper 2, Q3(c)(i) (2 marks): In a group of cattle, there are cattle with white-, red-, and roan- coloured hair. Height of cattle is also a genetically controlled characteristic. In the same
January 2023, Paper 2, Q6(b)(iii) (4 marks): A new RNA vaccine is being developed to treat rabies. RNA that codes for parts of the rabies virus protein coat are injected into the body. Cells then take up t
January 2023 (R), Paper 1, Q7(a) (1 mark): Which row in the table shows the number of chromosomes in the nucleus of a pollen grain, and in the nucleus of a root cell, of this grass? (1) Number of chromos
January 2023 (R), Paper 1, Q8(b)(i) (1 mark): Sex determination in dogs is controlled in the same way as in humans. Which combination of sex chromosomes is present in the body cells of a male dog? (1) A XX
January 2023 (R), Paper 1, Q8(b)(ii) (1 mark): How many individuals in this family have the genotype Nn? (1) A 2 B 4 C 5 D 6
January 2023 (R), Paper 1, Q8(b)(iii) (4 marks): Determine the probability that the next offspring produced by individuals P and Q is a male with sensory neuropathy. Include a genetic diagram in your answer. (
January 2023 (R), Paper 2, Q4(a) (1 mark): State what is meant by the term genome. (1)
January 2023 (R), Paper 2, Q4(b) (3 marks): Describe the differences between the structure of DNA and the structure of RNA. (3)
January 2023 (R), Paper 2, Q4(c) (4 marks): Describe the roles of RNA in protein synthesis. (4)
June 2022, Paper 1, Q8(a)(i) (2 marks): Explain which allele is dominant. (2)
June 2022, Paper 1, Q8(a)(ii) (4 marks): A male and female rat from these offspring are then mated together in a second cross. Some of the offspring of this second cross have agouti coloured fur and so
June 2022, Paper 1, Q8(a)(iii) (2 marks): Calculate the probability of any one offspring from this second cross being male with agouti coloured fur. (2) probability =
June 2022, Paper 1, Q8(b)(i) (1 mark): State the name of the type of genetic control where many genes control one phenotype. (1)
June 2022, Paper 2, Q6(b)(i) (2 marks): The strand of RNA used in this treatment is complementary to one strand of the DNA in the haemoglobin gene. Give the base sequence of RNA that is complementary
June 2022, Paper 2, Q6(b)(ii) (4 marks): Protein synthesis of the modified gene will produce haemoglobin. Describe the stages of this protein synthesis. (4)
June 2022, Paper 2, Q6(b)(iii) (4 marks): The standard treatment for beta thalassaemia is a weekly blood transfusion. The new treatment has so far been tested on two patients, with these results. • both
June 2022 (R), Paper 1, Q5(a)(i) (1 mark): State what is meant by the term gene. (1)
June 2022 (R), Paper 1, Q5(a)(ii) (1 mark): Give the possible genotypes of a chicken with normal feathers. (1)
June 2022 (R), Paper 1, Q5(b)(i) (1 mark): How many chickens in the family pedigree are heterozygous? (1) A 0 B 3 C 4 D 5
June 2022 (R), Paper 1, Q5(b)(ii) (4 marks): Use a genetic diagram to determine the probability of one of the offspring of individual 6 and individual 7 being a chicken with silkie feathers. (4) probabilit
June 2022 (R), Paper 1, Q5(b)(iii) (3 marks): The scientist observes that the chickens have either normal feathers or silkie feathers. However, the chickens have a wide range of different heights. Explain w
June 2022 (R), Paper 1, Q10(b) (4 marks): Llamas are large mammals that have evolved to live at high altitude where there is less oxygen in the atmosphere. The red blood cells of llamas can absorb more
January 2022, Paper 1, Q7(c)(iii) (4 marks): Describe how this reflex response could have evolved by natural selection. (4)
January 2022, Paper 1, Q9(a) (1 mark): State what is meant by a recessive allele. (1)
January 2022, Paper 1, Q9(b)(i) (4 marks): Draw a genetic diagram to show the genotypes of the woman and the man, the gametes they produce and the possible phenotypes and genotypes of the second child. (
January 2022, Paper 1, Q9(b)(ii) (1 mark): Calculate the probability that the second child is male and does not have the condition. (1) probability =
January 2022, Paper 1, Q9(c)(i) (1 mark): Describe what is meant by the control group. (1)
January 2022, Paper 1, Q9(c)(ii) (5 marks): The table compares the control group with the drug treatment group. It shows the numbers starting and completing the trial and those showing harmful effects. It
January 2022, Paper 2, Q1(b)(i) (1 mark): Read the passage below. Use the information in the passage and your own knowledge to answer the questions that follow. Making Enough Blood for the World A blood
January 2022, Paper 2, Q1(b)(ii) (1 mark): Read the passage below. Use the information in the passage and your own knowledge to answer the questions that follow. Making Enough Blood for the World A blood
January 2022, Paper 2, Q6(a) (1 mark): The diagram shows one strand of DNA from a section of a gene. ATTCCGAGT What would be the complementary sequence of bases on the messenger RNA produced from thi
January 2022, Paper 2, Q6(b) (1 mark): The diagram shows a stage during protein synthesis. X A A A C A G Which row gives the correct names for the stage of protein synthesis shown and the sequence of
January 2022, Paper 2, Q6(c) (3 marks): Explain how a mutation in a gene can affect the phenotype of an organism. (3)
January 2022, Paper 2, Q6(d)(ii) (5 marks): The results of the investigation are shown in the table. Percentage of butterflies with abnormalities Butterfly generation two months after the accident ten mon
January 2022 (R), Paper 1, Q1(b) (4 marks): The photograph shows a fennec fox. (Source: anolis01.123rf.com/PAL) Fennec foxes live in the Sahara Desert, which is very hot. They have very large ears and a t
January 2022 (R), Paper 1, Q7(a)(ii) (1 mark): State what is meant by a dominant allele. (1)
January 2022 (R), Paper 1, Q7(a)(iii) (4 marks): The diagram shows a family pedigree for cats with and without hypertrophic myopathy. 1 2 3 4 5 6 7 Key male with hypertrophic myopathy male without hypertrophic
January 2022 (R), Paper 1, Q7(a)(iv) (1 mark): Calculate the probability that the next offspring produced by individuals 6 and 7 is male and has hypertrophic myopathy. (1) probability =
January 2022 (R), Paper 1, Q7(b) (2 marks): Cat breeders often try to remove harmful alleles from populations by selective breeding. Suggest why it is more difficult to remove harmful recessive alleles fr
November 2021, Paper 1, Q7(a)(i) (1 mark): State what is meant by the term gene. (1)
November 2021, Paper 1, Q7(a)(ii) (1 mark): State the phenotype coded for by the dominant allele. (1)
November 2021, Paper 1, Q7(b) (4 marks): A male mouse and a female mouse with grey hair were chosen from the offspring of the first cross. These mice are mated in a second cross. Some of the offspring
November 2021, Paper 1, Q7(c) (2 marks): The scientist concludes that a mouse with grey hair could have two possible genotypes. Explain how the scientist could use a cross to determine the genotype of
November 2021, Paper 1, Q7(d) (3 marks): Albino mice have white hair. These mice also have pink eyes as they do not have pigment in their irises. They are also less likely to explore a new area when co
November 2021, Paper 2, Q2(c)(ii) (4 marks): Actinomycin D prevents transcription and cycloheximide prevents translation. Use this information and your own knowledge to explain the results of this investig
June 2021, Paper 1, Q7(a) (3 marks): Complete the table by giving the genotype of each individual. One has been done for you. (3) Individual Genotype P Q R Dd S
June 2021, Paper 1, Q7(b) (1 mark): The parents have a third child. Calculate the probability that this third child is female and has the condition. (1) probability =
June 2021, Paper 1, Q10(d) (4 marks): Modern humans have less body hair than their ancestors. Explain how this evolutionary change was brought about by natural selection. (4)
June 2021, Paper 2, Q5(a) (1 mark): The diagram shows part of one strand of DNA used to make urease. Complete the diagram by giving the missing bases on the other strand of DNA. (1) A T G G C T
January 2021, Paper 1, Q1(a) (1 mark): What is the maximum number of X chromosomes found in the nucleus of a sperm cell? (1) A 0 B 1 C 2 D 23
January 2021, Paper 1, Q4(a) (3 marks): The table gives some examples of biological processes. Complete the table by giving the name of each process. The first one has been done for you. (3) Example o
January 2021, Paper 1, Q4(b)(i) (4 marks): The zinc concentration in soil is higher near the zinc mine than it is further from the zinc mine. Explain how natural selection could be responsible for the re
January 2021, Paper 1, Q9(a)(i) (1 mark): Suggest why the person’s blood vessels may become blocked. (1)
January 2021, Paper 1, Q9(b)(i) (1 mark): State what is meant by the term recessive. (1)
January 2021, Paper 1, Q9(b)(ii) (2 marks): A man and a woman who are both heterozygous for the sickle cell allele have a child. Calculate the probability that the child will be female and not have sickle
January 2021, Paper 2, Q5(a)(i) (1 mark): How many amino acids does this sequence of bases code for? (1) A 1 B 3 C 5 D 15
January 2021, Paper 2, Q5(a)(ii) (2 marks): Write down the complementary mRNA code for this sequence of bases. (2)
January 2021, Paper 2, Q5(a)(iii) (2 marks): A student reads that DNA codons are non-overlapping. Suggest what is meant by the term non-overlapping. You should refer to the sequence of bases in your answer
January 2021, Paper 2, Q5(b) (4 marks): Describe what happens in the translation stage of protein synthesis. (4)
January 2021, Paper 2, Q5(c) (1 mark): State what is meant by the genome of an organism. (1)
January 2021 (R), Paper 1, Q5(a)(i) (2 marks): Explain how you can identify the sex of the person from the karyotype shown in Diagram 1. (2)
January 2021 (R), Paper 1, Q5(a)(ii) (2 marks): Cells can be described using the terms diploid or haploid. Explain the difference between these two terms using the information in Diagram 1. (2)
January 2021 (R), Paper 1, Q5(b)(i) (2 marks): Describe the differences between the karyotype in Diagram 1 and the karyotype in Diagram 2. (2)
January 2021 (R), Paper 1, Q5(b)(ii) (2 marks): Suggest how the karyotype in Diagram 2 may have been caused. (2)
January 2021 (R), Paper 1, Q5(b)(iii) (2 marks): The frequency of Klinefelter syndrome in the United Kingdom is 1 in every 660 males. The population of the United Kingdom is 66 million, of which 49% are male.
January 2021 (R), Paper 1, Q5(b)(iv) (1 mark): Suggest why females who are aged over 35 are more likely to give birth to a baby with the Klinefelter karyotype. (1)
January 2021 (R), Paper 2, Q1(b) (3 marks): Read the passage below. Use the information in the passage and your own knowledge to answer the questions that follow. Haemolytic disease Haemolysis is the term
January 2021 (R), Paper 2, Q1(e)(i) (3 marks): Read the passage below. Use the information in the passage and your own knowledge to answer the questions that follow. Haemolytic disease Haemolysis is the term
January 2021 (R), Paper 2, Q1(e)(ii) (1 mark): Read the passage below. Use the information in the passage and your own knowledge to answer the questions that follow. Haemolytic disease Haemolysis is the term
November 2020, Paper 1, Q1(a)(iii) (4 marks): Use the theory of evolution by natural selection to explain how H. pylori bacteria could have evolved to produce urease. (4)
November 2020, Paper 1, Q8(a)(i) (1 mark): Where are cells dividing by meiosis found in a human? (1) A kidney B penis C skin D testis
November 2020, Paper 1, Q8(a)(ii) (1 mark): Which part of a flowering plant is usually used to demonstrate cells dividing by mitosis? (1) A anther B cotyledon C root tip D xylem
November 2020, Paper 1, Q8(b) (6 marks): The table lists features comparing the processes of meiosis and mitosis in human cells. Complete the table by giving the missing information. (6) Feature Meiosi
November 2020, Paper 1, Q8(c)(i) (3 marks): Describe other causes of variation in offspring. (3)
November 2020, Paper 1, Q8(c)(ii) (2 marks): Scientists investigating a drug treatment use rats that are homozygous for many genes. Suggest the advantages of using rats that are homozygous for many genes.
November 2020, Paper 2, Q3(b)(i) (1 mark): What is the probability of this child having HD? (1) A 0.0 B 0.25 C 0.5 D 1.0
November 2020, Paper 2, Q3(b)(ii) (2 marks): These parents have three more children. The key shows the possible sex and phenotype of the individuals with or without HD. Key female with HD female without HD
November 2020, Paper 2, Q3(c) (3 marks): A drug can reduce the damage to nerve cells in the brains of people with HD. The drug binds to messenger RNA produced by the mutated gene for huntingtin protein
November 2020 (R), Paper 1, Q5(b) (2 marks): The amniotic fluid contains cells from the fetus. It is possible to look at chromosomes in these cells. A diagram of the chromosomes is called a karyotype. The
November 2020 (R), Paper 1, Q9(a)(i) (1 mark): phenotype (1)
November 2020 (R), Paper 1, Q9(a)(ii) (1 mark): gene (1)
November 2020 (R), Paper 1, Q9(a)(iii) (1 mark): allele. (1)
November 2020 (R), Paper 1, Q9(b)(i) (4 marks): Use a genetic diagram to show the genotypes of the parents, the gametes they can produce and all the possible genotypes and phenotypes of their children. (4)
November 2020 (R), Paper 1, Q9(b)(ii) (2 marks): The parents then have a second child. Calculate the probability that this child will be female and not have a cleft chin. (2) probability =
November 2020 (R), Paper 1, Q9(b)(iii) (1 mark): Sometimes a cleft chin does not develop even if the individual inherits the dominant allele. Suggest what might cause this. (1)
November 2020 (R), Paper 1, Q9(c) (3 marks): Most inherited conditions are not controlled by a single gene, but by many genes. Describe how a scientist could distinguish between a genetic condition in rats
November 2020 (R), Paper 2, Q4(e) (3 marks): GH increases transcription in cells. Explain why this affects the growth of rats. (3)
November 2020 (R), Paper 2, Q6(a) (1 mark): Which of these will not lead to an increase in genetic variation in a population of plants? (1) A asexual reproduction B insect pollination C mutation D wind po
November 2020 (R), Paper 2, Q6(b) (5 marks): Explain how a change in the DNA of a microorganism can reduce its ability to digest a substance. (5)
November 2020 (R), Paper 2, Q6(c) (4 marks): Explain why a change in DNA may not affect the phenotype of an organism. (4)
January 2020, Paper 1, Q7(a) (1 mark): Which of these describes the genotypes of the parent fruit flies? (1) A both are heterozygous B both are homozygous C both have long wings D one is heterozygous
January 2020, Paper 1, Q7(b)(i) (2 marks): Genetic diagrams are used to show how sex is inherited. Complete the genetic diagram to show that equal numbers of male and female offspring are produced. (2) X
January 2020, Paper 1, Q7(b)(ii) (2 marks): Explain why the results of the cross might not produce exactly equal numbers of male and female offspring. (2)
January 2020, Paper 2, Q4(a) (3 marks): State three ways in which the structure of a DNA molecule differs from the structure of an RNA molecule. (3) 1 2 3
January 2020, Paper 2, Q4(b) (5 marks): Describe the differences between the processes of transcription and translation. (5)
January 2020, Paper 2, Q4(c) (3 marks): The DNA molecule codes for the amino acids used to make proteins. There are four different bases in DNA and 20 amino acids used to make proteins. Use this infor
January 2020, Paper 2, Q7(a) (1 mark): Give the genotype of the yellow parent mice that would produce this 3 : 1 ratio. (1)
January 2020, Paper 2, Q7(b) (1 mark): The scientist then crosses three other pairs of male and female yellow mice. The table shows his results. Number of offspring yellow brown Cross one 7 3 Cross t
January 2020, Paper 2, Q7(c) (4 marks): Suggest reasons why the predicted ratio of 3 : 1 is not obtained. (4)
January 2020 (R), Paper 1, Q4(b) (3 marks): Antibiotics can be used to cure some infections. Some bacteria are resistant to antibiotics. Explain how resistance to an antibiotic occurs and increases in a p
January 2020 (R), Paper 1, Q4(c)(i) (2 marks): Calculate the percentage increase in the predicted number of deaths in 2050 compared with the number of deaths in 2014. (2) percentage increase =
January 2020 (R), Paper 1, Q4(c)(ii) (4 marks): A doctor claims that if he stops giving antibiotics to any patients who are ill, he can reduce the number of predicted deaths caused by resistant bacteria in 20
January 2020 (R), Paper 1, Q9(a)(i) (4 marks): Use a genetic diagram to show the genotypes of the parents, the possible gametes and the genotype and phenotype of their child. Use D to represent the dominant
January 2020 (R), Paper 1, Q9(a)(ii) (2 marks): Determine the probability that the second child of these parents will be a girl with syndactyly. (2) probability =
January 2020 (R), Paper 1, Q9(b) (3 marks): Another type of syndactyly is caused by a recessive allele. Explain the differences in the pattern of inheritance between a condition caused by a dominant allel
January 2020 (R), Paper 1, Q9(c) (2 marks): Syndactyly is controlled by a single gene that has two alleles. Most other phenotypes are the result of a different sort of genetic control. Describe the geneti
January 2020 (R), Paper 2, Q5(a) (2 marks): Give two differences between the structure of a DNA molecule and the structure of an RNA molecule. (2) 1 2
January 2020 (R), Paper 2, Q5(b)(i) (1 mark): Give the sequence of bases in the mRNA that would be produced from this strand. (1)
January 2020 (R), Paper 2, Q5(b)(ii) (1 mark): The sequence of bases in the mRNA is used to code for the amino acids in a protein. Calculate the number of bases required to code for an amino acid chain of 14
January 2020 (R), Paper 2, Q5(c) (4 marks): A mutation results in a change in the sequence of bases in a DNA strand. Discuss what effect a change in the sequence of bases could have on the functioning of
January 2020 (R), Paper 2, Q5(d) (1 mark): Give one way that the incidence of mutation could be increased. (1)
June 2019, Paper 1, Q3(c) (4 marks): The diagram shows sandpipers feeding. Sandpipers have long beaks so that they can dig for worms in the mud. (Source: © Birchside www.fotosearch.com) Explain how
June 2019, Paper 2, Q3(a)(iii) (5 marks): Amylase is a protein. Describe how protein is made in a cell. (5)
June 2019, Paper 2, Q5(a) (1 mark): Give the sex chromosomes in the body cell of a human male. (1)
June 2019, Paper 2, Q5(b)(i) (1 mark): What are the sex chromosomes in the body cell of a male bird? (1) A XY B ZW C ZY D ZZ
June 2019, Paper 2, Q5(b)(ii) (2 marks): A male and female bird have four offspring. Calculate the probability that these offspring will all be female. (2) probability =
June 2019 (R), Paper 1, Q2(c)(i) (1 mark): Name the type of cell division affected by pollution in this investigation. (1)
June 2019 (R), Paper 1, Q7(a)(i) (1 mark): Human height is under polygenic control. State the meaning of the term polygenic. (1)
June 2019 (R), Paper 1, Q7(a)(ii) (2 marks): Using the graph, determine the mode and median heights for males and females. (2) Mode Median Females Males
June 2019 (R), Paper 1, Q7(a)(iii) (2 marks): Suggest two reasons why the mean height for males is greater than the mean height for females. (2) 1 2
June 2019 (R), Paper 1, Q7(b)(i) (4 marks): Use your knowledge of genetics to explain the phenotypes of these children. Use H to represent the allele for a white patch of hair and h to represent the allel
June 2019 (R), Paper 1, Q7(b)(ii) (2 marks): Another condition, called vitiligo, produces similar symptoms to piebaldism but is not genetically controlled. Suggest how a doctor could diagnose whether a new
June 2019 (R), Paper 2, Q5(b) (2 marks): PFK is caused by a recessive allele. The table lists the genotypes of some parents. Complete the table by giving the percentage of offspring likely to have PFK
June 2019 (R), Paper 2, Q5(c) (2 marks): A dog breeder is someone who breeds dogs and sells the offspring. Explain the advantage for the dog breeder of using homozygous dominant dogs as parents. (2)
June 2019 (R), Paper 2, Q5(d) (2 marks): A dog breeder buys a healthy dog. The dog shows no signs of PFK, but the breeder does not know its genotype. Explain why the breeder mates this dog with a dog t
June 2019 (R), Paper 2, Q5(e)(i) (1 mark): Which of these shows the base sequence of mRNA produced from this strand of DNA? (1) A CAGGTATGG B CAGGUAUGG C GTCCATACC D GUCCAUACC
June 2019 (R), Paper 2, Q5(e)(ii) (3 marks): The mutated base sequence for the same strand of DNA is CAGTTATGG. Explain why the mutated base sequence makes a different protein than the normal DNA. (3)

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