Meiosis, gametes and fertilisation: Edexcel International A Level Biology questions

Every Edexcel International A Level Biology exam question on Meiosis, gametes and fertilisation (specification points 3.9–3.13), 2019–2025, with its mark scheme and examiner’s report.

All 120 questions on Meiosis, gametes and fertilisation, as a list

June 2025, AS Unit 2, Q3(a) (1 mark): Pollen grains contain a generative nucleus. The generative nucleus divides to form two male nuclei. Which statement is correct? (1) A one male nucleus is involv
June 2025, AS Unit 2, Q3(b)(i) (1 mark): Name the stage of meiosis when crossing over of chromatids occurs. (1)
June 2025, AS Unit 2, Q3(b)(ii) (2 marks): Describe two other processes that can give rise to genetic variation in the offspring of the passion flower. (2) 1 2
June 2025, AS Unit 2, Q8(a) (3 marks): The acrosome reaction is stimulated when a sperm cell binds to the ZP3 protein on the zona pellucida of an egg cell. Describe the acrosome reaction. (3)
June 2025, AS Unit 2, Q8(b)(i) (3 marks): Suggest why some sperm cells may not be able to bind to the sperm receptor on the egg cell surface membrane. (3)
June 2025, AS Unit 2, Q8(b)(ii) (2 marks): Explain how more sperm cells are prevented from entering the egg cell. (2)
January 2025, AS Unit 2, Q1(a)(i) (1 mark): Complete the diagram by drawing and labelling a flagellum and an acrosome. (1)
January 2025, AS Unit 2, Q1(a)(ii) (1 mark): Give the function of the mitochondria in the midpiece of the sperm. (1)
January 2025, AS Unit 2, Q1(b)(i) (2 marks): Give two conclusions that can be drawn from these data. (2) 1 2
January 2025, AS Unit 2, Q1(b)(ii) (1 mark): Give the name of a statistical test that could be used to assess the strength of the relationship between length of midpiece and swimming speed of sperm cells.
January 2025, AS Unit 2, Q5(a) (3 marks): Complete this graph to show how the DNA content per cell would change when a cell, with 2 a.u. of DNA, undergoes meiosis to produce gametes. (3) 6 4 DNA content
January 2025, AS Unit 2, Q5(c) (5 marks): The photograph shows a bee on a peony flower. leaf of peony plant peony ﬂower bee (Source: © Boris Zhitkov / Alamy Stock Photo) Pollen grains from the leg of th
January 2025, AS Unit 3, Q2(a) (2 marks): Describe the role of the pollen tube in plant reproduction. (2)
January 2025, AS Unit 3, Q2(b)(ii) (6 marks): Describe how the data in the table could be obtained. (6)
January 2025, AS Unit 3, Q2(b)(iii) (3 marks): Comment on the results of this investigation. (3)
October 2024, AS Unit 2, Q3(c) (4 marks): The diagram shows a germinating pollen grain. generative nucleus tube nucleus Describe the roles of the tube nucleus and the generative nucleus. (4) Tube nucleu
October 2024, AS Unit 2, Q4(a) (1 mark): A sperm cell swims by rotating its flagellum. Which of the following statements about sperm cells are correct? 1. sperm cells are diploid 2. the flagellum rotat
October 2024, AS Unit 2, Q4(b) (3 marks): Describe how the nucleus of a sperm cell enters an egg cell. (3)
October 2024, AS Unit 2, Q4(c)(ii) (3 marks): Suggest how these enzymes will prevent more than one sperm nucleus entering the egg cell. (3)
October 2024, AS Unit 2, Q6(b)(i) (4 marks): A zygote is formed at fertilisation. Explain how an error in meiosis could result in the production of a zygote with three copies of chromosome 13. (4)
October 2024, AS Unit 2, Q6(c) (1 mark): An individual can also develop Patau syndrome if part of chromosome 13 becomes attached to a different chromosome during prophase I. Suggest a reason why part o
June 2024, AS Unit 2, Q4(a) (3 marks): One specialised cell is the sperm cell. Draw a mammalian sperm cell showing the acrosome, the nucleus and a mitochondrion. Label the acrosome, nucleus and mitoc
June 2024, AS Unit 2, Q4(b)(i) (1 mark): A human egg cell has a radius of 50 µm. Calculate the volume of this human egg cell. Use the formula: 4 = 3 r3 π V (1) Answer µm3
June 2024, AS Unit 2, Q4(b)(ii) (1 mark): The surface area of this egg cell is 31 416 µm2. Give the surface area to volume ratio of this egg cell. (1) Answer : 1
June 2024, AS Unit 2, Q4(b)(iii) (3 marks): Explain three ways in which a mammalian egg cell is specialised for its functions. (3)
June 2024, AS Unit 2, Q5(a)(i) (1 mark): These alleles are found at the same locus. State what is meant by the term locus. (1)
June 2024, AS Unit 2, Q7(a) (3 marks): The body cells of the mother Malayan tapir have some genetic similarities to and differences from the cells of her baby. Explain why the body cells of the mothe
January 2024, AS Unit 2, Q4(a)(i) (1 mark): The pollen tube growth rate is 0.2 µm s–1. How long would it take the pollen tube to grow 15 mm? (1) A 75 seconds B 125 minutes C 1 250 minutes D 7 500 seconds
January 2024, AS Unit 2, Q4(b) (4 marks): The diagram shows a pollen tube that has grown to reach an ovule. pollen tube polar nuclei female gamete Fertilisation of the female polar nuclei results in the
January 2024, AS Unit 2, Q6(c)(i) (1 mark): The photograph shows some sperm cells, as seen using a microscope. ×4000 (Source: © MedicalRF.com/Alamy Stock Photo) Which of the following statements about hum
January 2024, AS Unit 2, Q6(c)(ii) (6 marks): The photograph shows a sperm cell being injected into a human egg cell during the process of in‑vitro fertilisation (IVF). (Source: © Phanie / Alamy Stock Photo
October 2023, AS Unit 2, Q1(b) (2 marks): Explain why it is possible for chromatid A to be genetically different from chromatid B. (2)
October 2023, AS Unit 2, Q1(c) (2 marks): A student was asked to draw the four haploid cells produced by this cell in metaphase I of meiosis. The diagram shows the incomplete drawings produced by this s
October 2023, AS Unit 2, Q2(b) (3 marks): A pollen grain can produce a pollen tube that contains a generative nucleus. Plant fertilisation results in the production of an embryo and endosperm tissue. Th
October 2023, AS Unit 2, Q2(c)(i) (1 mark): State what is meant by the term linkage with reference to these two genes. (1)
October 2023, AS Unit 2, Q2(c)(ii) (1 mark): A statistical test can be used to analyse observed phenotype frequencies and expected phenotype frequencies for the foxglove plants. Which of the following stat
October 2023, AS Unit 2, Q7(a)(ii) (1 mark): Suggest one function of the yolk in the fertilised fish egg cell. (1)
October 2023, AS Unit 2, Q8(a)(i) (1 mark): State the letter which shows the zona pellucida. (1)
October 2023, AS Unit 2, Q8(a)(ii) (1 mark): The student did not include the structures that contain enzymes involved in hardening the zona pellucida. Name these structures. (1)
October 2023, AS Unit 2, Q8(b)(i) (1 mark): How many of the following statements about sperm cells are correct? • The mid‑piece of the sperm cell contains many mitochondria for anaerobic respiration. • Th
October 2023, AS Unit 2, Q8(b)(ii) (1 mark): Sperm cells with a larger acrosome to nucleus ratio have an increased swimming speed. Calculate the acrosome to nucleus ratio for the reed bunting sperm cell sh
October 2023, AS Unit 2, Q8(b)(iii) (4 marks): The effect of the width of the helical membrane on the mean swimming speed of sperm cells from different bird species was investigated. The graph shows the resu
October 2023, AS Unit 2, Q8(c) (3 marks): An individual organism that can produce both egg cells and sperm cells is said to be a hermaphrodite. Blue dragons (Glaucus atlanticus) are sea slugs that are h
June 2023, AS Unit 2, Q2(b) (2 marks): Inheritance of different versions of these two genes shows genetic linkage. Explain how the phenotypes of an individual can show genetic linkage in the inherita
June 2023, AS Unit 2, Q5(b)(i) (1 mark): State the relationship between the mean length and swimming speed of the sperm cells of these cichlid species. (1)
June 2023, AS Unit 2, Q5(b)(ii) (1 mark): A scientist wanted to assess the strength of the relationship between these two variables. Which statistical test should be used to assess the strength of the r
June 2023, AS Unit 2, Q5(b)(iii) (1 mark): Suggest one advantage for a male cichlid of producing sperm cells with a faster swimming speed. (1)
June 2023, AS Unit 2, Q5(c)(i) (1 mark): Which labelled structure is an acrosome? (1) A W B X C Y D Z
June 2023, AS Unit 2, Q6(a)(i) (3 marks): Explain how meiosis causes this genetic variation. (3)
June 2023, AS Unit 2, Q6(a)(ii) (2 marks): Give two differences in the arrangement of the DNA in a cell at the beginning of interphase and at the end of prophase I. (2) 1 2
June 2023, AS Unit 2, Q6(b) (1 mark): The DNA content of two cells was compared. Cell A was undergoing mitosis. The mass of DNA in the cell in prophase was 12 pg. Cell B was undergoing meiosis. The
June 2023, AS Unit 2, Q6(c) (6 marks): Plants can produce seeds from either cross‑fertilisation or self‑fertilisation. Self‑fertilisation occurs when male nuclei from a flower fertilises an egg cell
June 2023, AS Unit 3, Q2(a) (2 marks): The diagram shows a germinating pollen grain. A B Give a function for each of the structures labelled A and B. (2) A . B
June 2023, AS Unit 3, Q2(b) (5 marks): The percentage germination of the pollen grains was used to determine the viability of the pollen. Describe a procedure to compare the percentage germination of
June 2023, AS Unit 3, Q2(c)(i) (4 marks): The effect of temperature on percentage germination of pollen collected by both methods was investigated. The results are shown in the graph. 70 60 50 Percentag
June 2023, AS Unit 3, Q2(c)(ii) (4 marks): Describe how the investigation could be modified to allow the significance of the difference between the percentage germination for bee collected pollen and han
June 2023, AS Unit 3, Q2(d)(i) (3 marks): Calculate the percentage difference in pollen tube length between the optimum pH for hand collected pollen and the optimum pH for bee collected pollen. Give you
June 2023, AS Unit 3, Q2(d)(ii) (1 mark): Suggest one reason for the differences in tube growth of the pollen collected by these two methods. (1)
January 2023, AS Unit 2, Q2(a)(i) (1 mark): Complete the diagram to show the number of chromosomes in the female and male gametes. (1)
January 2023, AS Unit 2, Q2(a)(ii) (1 mark): Label the part of the diagram where meiosis would have occurred. (1)
January 2023, AS Unit 2, Q2(b)(i) (1 mark): Which letter labels an ovule? (1) A P B Q C S D T
January 2023, AS Unit 2, Q2(b)(ii) (1 mark): Which letter labels an egg cell (female gamete)? (1) A P B S C T D U
January 2023, AS Unit 2, Q2(b)(iii) (1 mark): Which letter labels a male nucleus? (1) A R B S C T D U
January 2023, AS Unit 2, Q2(b)(iv) (1 mark): Which letter labels a polar nucleus? (1) A R B S C T D U
January 2023, AS Unit 2, Q2(b)(v) (2 marks): Describe the function of the tube nucleus. (2)
January 2023, AS Unit 2, Q4(a)(i) (1 mark): An unfertilised egg cell is 2.3 mm in diameter. Calculate the volume of the egg cell, using the formula: 4 π 3 3 r V = Give your answer to one decimal place. (1
January 2023, AS Unit 2, Q4(a)(ii) (2 marks): An unfertilised pike egg cell has a larger volume than a pike sperm cell. Explain why an egg cell has a larger volume than a sperm cell. (2)
January 2023, AS Unit 2, Q4(c)(i) (2 marks): Describe the adaptations of a sperm cell that allow movement. (2)
January 2023, AS Unit 2, Q4(c)(ii) (2 marks): Give two conclusions for this investigation. (2) 1 2
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)
October 2022, AS Unit 2, Q6(a)(ii) (1 mark): Which part of the sperm cell contains enzymes that are released to break down the zona pellucida? (1) A W B X C Y D Z
June 2022, AS Unit 2, Q1(b)(ii) (4 marks): Gametes are specialised for their functions. Complete the table to show the correct statement for each structure found in gametes. (4) Propels male Modified by
June 2022, AS Unit 2, Q4(b)(i) (1 mark): State what is meant by the term locus. (1)
June 2022, AS Unit 2, Q4(b)(ii) (3 marks): Explain how the chromosomes of an Indian muntjac egg cell could differ from those in a body cell. (3)
June 2022, AS Unit 2, Q4(c) (2 marks): Chinese muntjac cells contain 23 pairs of chromosomes. The photograph shows a Chinese muntjac. (Source: © Design Pics Inc / Alamy Stock Photo) The Chinese muntj
June 2022, AS Unit 2, Q6(b)(ii) (1 mark): The investigation used 2500 egg cells for each sample of sperm cells. Calculate the number of egg cells that would have been fertilised by sperm cells with 2.5
June 2022, AS Unit 2, Q6(b)(iii) (4 marks): Explain why a higher activity of the digestive enzyme acrosin resulted in a higher percentage of egg cells being fertilised. (4)
June 2022, AS Unit 2, Q6(c)(ii) (3 marks): Suggest why this fertilised egg cell has three nuclei. (3)
June 2022, AS Unit 2, Q7(a)(i) (1 mark): How many of the following statements about a pollen grain are correct? • contains a tube nucleus and a generative nucleus • the generative nucleus divides by mi
June 2022, AS Unit 2, Q7(a)(ii) (2 marks): The table gives information about the surface area and volume of round and long pollen grains. Volume Surface area to Pollen grain shape Surface area / μm3 volu
June 2022, AS Unit 2, Q7(c) (4 marks): Sweet pea plants were used in an investigation into the inheritance of flower colour, pollen grain length and pea pod shape. Each of these traits is controlled
June 2022, AS Unit 3, Q1(a)(i) (3 marks): Explain the role of the pollen tube in plant reproduction. (3)
June 2022, AS Unit 3, Q1(a)(ii) (2 marks): Explain why pollen tubes grow in the same direction from the stigma, after pollination. (2)
June 2022, AS Unit 3, Q1(d)(ii) (3 marks): Comment on the conclusion that both percentage germination and mean pollen tube growth have the same optimum sucrose concentration. (3)
January 2022, AS Unit 2, Q8(b) (4 marks): The graph shows the speed of individual sperm compared with bundles of sperm in liquids of different resistance. 25 sperm bundles 20 individual sperm 15 Speed o
January 2022, AS Unit 2, Q8(c)(i) (1 mark): When the highest sperm concentration was added to the egg cells with damaged zona pellucida, the percen
January 2022, AS Unit 2, Q8(c)(ii) (4 marks): Explain the results of this investigation. (4)
October 2021, AS Unit 2, Q7(a) (6 marks): Animals of this species are either male or hermaphrodites. Nematodes that inherit one sex chromosome are male. Nematodes that inherit two sex chromosomes are he
October 2021, AS Unit 2, Q8(a) (2 marks): Explain how an egg cell is specialised for its function. (2)
October 2021, AS Unit 2, Q8(b)(i) (3 marks): Compare and contrast metaphase in mitosis and meiosis. (3)
October 2021, AS Unit 2, Q8(c)(i) (2 marks): Calculate the value for ∑D 2. Use the table to help you. (2) ∑D 2 =
October 2021, AS Unit 2, Q8(c)(ii) (2 marks): Calculate the correlation coefficient, rs value, for this data using the formula: (2) − ( ) ∑ 6 D 2 r s = 1 ( ) − n n 2 1 Answer
October 2021, AS Unit 2, Q8(c)(iii) (2 marks): The null hypothesis is that there was no significant correlation between the age of the chicken and the mass of the eggs laid. Another scientist replicated this
June 2021, AS Unit 2, Q3(a)(i) (1 mark): How many of the following statements about this diagram are correct? • there are three gene loci • the pair of chromosomes will be separated into different cell
June 2021, AS Unit 2, Q3(b)(i) (1 mark): Name the stage of meiosis in which crossing over begins. (1)
June 2021, AS Unit 2, Q3(b)(ii) (1 mark): How many of the following combinations could result from one crossover of the chromosomes shown in the diagram? • AbE • ABe • abE • abe (1) A one B two C three
June 2021, AS Unit 2, Q3(b)(iii) (2 marks): Explain why alleles b and e are more likely to be inherited together than alleles A and e. (2)
June 2021, AS Unit 2, Q6(a) (4 marks): Explain how cortical granules ensure that the egg cell is diploid after fertilisation. (4)
June 2021, AS Unit 2, Q6(b) (6 marks): Organisms have evolved different mating strategies such as: • Some male animals have sperm cells with longer middle regions, as shown in the diagram. middle reg
June 2021, AS Unit 3, Q3(c)(ii) (2 marks): Describe the effect of boric acid concentration on pollen grain germination at 4 hours. (2)
June 2021, AS Unit 3, Q3(d)(i) (2 marks): During the first two hours, the rate of pollen tube growth at a boric acid concentration of 100 mg dm–3 is 130.5 µm hour–1. Calculate the percentage increase in
June 2021, AS Unit 3, Q3(d)(ii) (4 marks): Describe how the results shown in the graph could have been obtained. You are provided with a 500 mg dm–3 boric acid solution. (4)
June 2021, AS Unit 3, Q3(e) (2 marks): Compare and contrast the effect of boric acid concentration on pollen grain germination with its effect on pollen tube growth. Use the information given in this
June 2021, Unit 4, Q1(b)(iv) (1 mark): It was suggested that the chromosomes in class 2 mosses were found in pairs. Give the evidence that supports this suggestion. (1)
January 2021, AS Unit 2, Q3(a) (5 marks): Double fertilisation takes place in the ovules. Describe the events that occur from the time a pollen grain lands on the stigma to the production of a triploid
January 2021, AS Unit 2, Q3(b) (4 marks): The photograph shows flowers from a silver trumpet tree in Thailand. (Source: © Picture/Shutterstock) Flowering plants such as the silver trumpet tree contain s
January 2021, AS Unit 2, Q4(b)(i) (1 mark): As mouse egg cells develop they accumulate small spherical lipid droplets. These lipid droplets have a mean radius of 88 µm. The volume of a sphere (V) is calcu
January 2021, AS Unit 2, Q4(b)(iii) (3 marks): Describe the events that occur after a sperm cell enters an egg cell, until a zygote is formed. (3)
October 2020, AS Unit 2, Q3(b)(ii) (2 marks): Complete the graph to show how the DNA content would change if the cell had undergone meiosis to form gametes. (2) 6 4 DNA content / a.u. 2 0 0 5 10 15 20 25 Ti
October 2020, AS Unit 2, Q4(c) (3 marks): The endosperm of a grain of wheat develops from the endosperm nucleus, formed during fertilisation. Explain the role of the pollen tube and nuclei in the format
October 2020, AS Unit 2, Q7(a)(i) (1 mark): In which stage of meiosis does independent assortment occur? (1) A metaphase I B metaphase II C telophase I D telophase II
October 2020, AS Unit 2, Q7(a)(ii) (1 mark): In which stage of meiosis does crossing over occur? (1) A metaphase I B metaphase II C prophase I D prophase II
October 2020, AS Unit 2, Q7(b) (3 marks): Genetic variation increases due to the production of new combinations of alleles. A cell has gene A and gene B with alleles A, a and B, b. Meiosis could produce
January 2020, AS Unit 2, Q4(c) (3 marks): Pea plants produce flowers. Some cells in the flowers undergo meiosis. Explain how the separation of chromosomes in meiosis gives rise to genetic variation in t
June 2019, AS Unit 2, Q3(a) (2 marks): Meiosis produces gametes that are genetically different. Crossing over is important to increase genetic variation. The diagram shows one pair of homologous chro
June 2019, AS Unit 2, Q7(b) (3 marks): The photograph shows a Chinese hamster. Magnification ×1 A female Chinese hamster mates with many males in a short period of time. The diagram shows the relativ
June 2019, AS Unit 2, Q7(c) (3 marks): Explain the role of the cortical reaction in the process of fertilisation in mammals. (3)
June 2019, AS Unit 3, Q1(a)(iii) (3 marks): Explain why the results might have been affected if the variable you named in (a)(ii) had not been controlled. (3)
June 2019, AS Unit 3, Q1(c)(i) (2 marks): Calculate the percentage increase in pollen tube length at 100 ppm compared with that at 25 ppm. (2) Answer %
June 2019, AS Unit 3, Q1(c)(ii) (5 marks): You are provided with a solution containing 500 g dm–3 of sucrose . Devise a procedure to investigate the effect of different concentrations of sucrose on the r

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