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Adaptations for gas exchange: Eduqas A‑Level Biology questions

Every Eduqas A-Level Biology exam question on 3.1 Adaptations for gas exchange, 2016–2025, with its mark scheme and examiner’s report.

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2,061 questions

  1. Q2(b)(i)

    June 2025 · Component 2

    1 mark3.1 Adaptations for gas exchange
    The whole paper ↗
    June 2025 Component 2, question 2(b)(i): Using a label (A–E) from Image 2.2, identify from which cell the chloroplast was taken. Name the tissue in which this cell would have been found. [1] Cell Name

  2. Q5(a)

    June 2025 · Component 3

    2 marks3.1 Adaptations for gas exchange
    The whole paper ↗
    June 2025 Component 3, question 5(a): Explain why larger organisms require specialised gas exchange surfaces. [2]

  3. Q1(a)

    June 2025 · AS Component 2

    4 marks3.1 Adaptations for gas exchange
    The whole paper ↗
    June 2025 AS Component 2, question 1(a): An amoeba and a flatworm have no additional structures associated with their gas exchange surfaces, whereas an earthworm has capillaries close to the surface of

  4. Q1(b)(i)

    June 2025 · AS Component 2

    2 marks3.1 Adaptations for gas exchange
    The whole paper ↗
    June 2025 AS Component 2, question 1(b)(i): Calculate the mean percentage oxygen saturation in the blood of earthworms treated with adrenaline. Write your answer in Table 1.2.  [2]

  5. Q1(b)(ii)

    June 2025 · AS Component 2

    1 mark3.1 Adaptations for gas exchange
    The whole paper ↗
    June 2025 AS Component 2, question 1(b)(ii): Explain why a mean was calculated for each condition, rather than using a single reading from one earthworm.  [1]

  6. Q1(b)(iii)

    June 2025 · AS Component 2

    2 marks3.1 Adaptations for gas exchange
    The whole paper ↗
    June 2025 AS Component 2, question 1(b)(iii): Explain how the readings in Table 1.2 are consistent with the observation that earthworms are more active in moist soil than in air.  [2]

  7. Q1(b)(iv)

    June 2025 · AS Component 2

    2 marks3.1 Adaptations for gas exchange
    The whole paper ↗
    June 2025 AS Component 2, question 1(b)(iv): When the earthworms are treated with adrenaline, the blood vessels near the body surface become constricted. Suggest how this might account for the effect of ad

  8. Q1(b)(v)

    June 2025 · AS Component 2

    1 mark3.1 Adaptations for gas exchange
    The whole paper ↗
    June 2025 AS Component 2, question 1(b)(v): Use Table 1.2 to suggest one limitation in the data collected in this investigation.  [1]

  9. Q1(b)(vi)

    June 2025 · AS Component 2

    2 marks3.1 Adaptations for gas exchange
    The whole paper ↗
    June 2025 AS Component 2, question 1(b)(vi): Earthworms have an optimum temperature range of 10–16 °C. Suggest how the readings shown in Table 1.2 might be different if the experiments had been conducted o

  10. Q1(c)

    June 2025 · AS Component 2

    2 marks3.1 Adaptations for gas exchange
    The whole paper ↗
    June 2025 AS Component 2, question 1(c): Bony fish use counter current flow, which increases the percentage oxygen saturation in their blood. Describe what is meant by counter current flow. Explain how

  11. Q1(a)(i)

    June 2024 · Component 3

    3 marks3.1 Adaptations for gas exchange
    The whole paper ↗
    June 2024 Component 3, question 1(a)(i): Add labels to Image 1.2 to identify three tissue layers that contain photosynthesising cells. [3]

  12. Q1(a)(ii)

    June 2024 · Component 3

    3 marks3.1 Adaptations for gas exchange
    The whole paper ↗
    June 2024 Component 3, question 1(a)(ii): The proportions of (A–C : A–B) in Image 1.1 have a ratio of 3.5 : 1 I. Calculate the ratio of (A–C : A–B) in Image 1.2. [1] Ratio = : 1 II. Image 1.2 has not be

  13. Q1(b)

    June 2024 · Component 3

    4 marks3.1 Adaptations for gas exchange
    The whole paper ↗
    June 2024 Component 3, question 1(b): To photosynthesise effectively, a leaf is adapted for the absorption of light energy and for diffusion of gases. State two adaptations of a leaf for the absorpt

  14. Q6

    June 2024 · Component 3

    9 marks3.1 Adaptations for gas exchange
    The whole paper ↗
    June 2024 Component 3, question 6: Multicellular animals have evolved different ways of ventilating their gas exchange surfaces. Image 6.1 shows the thorax of a human (a mammal), Image 6.2 shows

  15. Q3(b)(i)

    June 2024 · AS Component 2

    2 marks3.1 Adaptations for gas exchange
    The whole paper ↗
    June 2024 AS Component 2, question 3(b)(i): State why the insect was left for one hour at the experimental temperature before recording data. Explain your answer. [2] To prevent CO2 production increasing

  16. Q3(b)(ii)

    June 2024 · AS Component 2

    1 mark3.1 Adaptations for gas exchange
    The whole paper ↗
    June 2024 AS Component 2, question 3(b)(ii): Suggest one reason why feeding might increase CO2 production in these insects. [1] Image 3.3 shows recordings from the experiment. Image 3.3 A Temperature = 18°

  17. Q3(b)(iii)

    June 2024 · AS Component 2

    2 marks3.1 Adaptations for gas exchange
    The whole paper ↗
    June 2024 AS Component 2, question 3(b)(iii): With reference to the partial pressure of carbon dioxide in the tracheoles, explain the reason for the following trends observed in Image 3.3 [2] Trend I: As te

  18. Q4(a)(i)

    June 2024 · AS Component 2

    2 marks3.1 Adaptations for gas exchange
    The whole paper ↗
    June 2024 AS Component 2, question 4(a)(i): Explain the advantage of closing stomata at night and why the plant is at a disadvantage if the stomata were to close at midday. [2]

  19. Q4(a)(ii)

    June 2024 · AS Component 2

    3 marks3.1 Adaptations for gas exchange
    The whole paper ↗
    June 2024 AS Component 2, question 4(a)(ii): Guard cells in Image 4.1A are turgid. ATP is required for them to achieve this state. Describe the mechanism that enables guard cells to become turgid. [3]

  20. Q4(b)(i)

    June 2024 · AS Component 2

    2 marks3.1 Adaptations for gas exchange
    The whole paper ↗
    June 2024 AS Component 2, question 4(b)(i): One way to measure the extent of stomatal opening is to calculate the aspect ratio. Aspect ratio (AR) = length of stomatal opening (L) width of stomatal opening
All 138 questions on Adaptations for gas exchange, as a list
  1. June 2025, Component 2, Q2(b)(i) (1 mark): Using a label (A–E) from Image 2.2, identify from which cell the chloroplast was taken. Name the tissue in which this cell would have been found. [1] Cell Name
  2. June 2025, Component 3, Q5(a) (2 marks): Explain why larger organisms require specialised gas exchange surfaces. [2]
  3. June 2025, AS Component 2, Q1(a) (4 marks): An amoeba and a flatworm have no additional structures associated with their gas exchange surfaces, whereas an earthworm has capillaries close to the surface of
  4. June 2025, AS Component 2, Q1(b)(i) (2 marks): Calculate the mean percentage oxygen saturation in the blood of earthworms treated with adrenaline. Write your answer in Table 1.2.  [2]
  5. June 2025, AS Component 2, Q1(b)(ii) (1 mark): Explain why a mean was calculated for each condition, rather than using a single reading from one earthworm.  [1]
  6. June 2025, AS Component 2, Q1(b)(iii) (2 marks): Explain how the readings in Table 1.2 are consistent with the observation that earthworms are more active in moist soil than in air.  [2]
  7. June 2025, AS Component 2, Q1(b)(iv) (2 marks): When the earthworms are treated with adrenaline, the blood vessels near the body surface become constricted. Suggest how this might account for the effect of ad
  8. June 2025, AS Component 2, Q1(b)(v) (1 mark): Use Table 1.2 to suggest one limitation in the data collected in this investigation.  [1]
  9. June 2025, AS Component 2, Q1(b)(vi) (2 marks): Earthworms have an optimum temperature range of 10–16 °C. Suggest how the readings shown in Table 1.2 might be different if the experiments had been conducted o
  10. June 2025, AS Component 2, Q1(c) (2 marks): Bony fish use counter current flow, which increases the percentage oxygen saturation in their blood. Describe what is meant by counter current flow. Explain how
  11. June 2024, Component 3, Q1(a)(i) (3 marks): Add labels to Image 1.2 to identify three tissue layers that contain photosynthesising cells. [3]
  12. June 2024, Component 3, Q1(a)(ii) (3 marks): The proportions of (A–C : A–B) in Image 1.1 have a ratio of 3.5 : 1 I. Calculate the ratio of (A–C : A–B) in Image 1.2. [1] Ratio = : 1 II. Image 1.2 has not be
  13. June 2024, Component 3, Q1(b) (4 marks): To photosynthesise effectively, a leaf is adapted for the absorption of light energy and for diffusion of gases. State two adaptations of a leaf for the absorpt
  14. June 2024, Component 3, Q6 (9 marks): Multicellular animals have evolved different ways of ventilating their gas exchange surfaces. Image 6.1 shows the thorax of a human (a mammal), Image 6.2 shows
  15. June 2024, AS Component 2, Q3(b)(i) (2 marks): State why the insect was left for one hour at the experimental temperature before recording data. Explain your answer. [2] To prevent CO2 production increasing
  16. June 2024, AS Component 2, Q3(b)(ii) (1 mark): Suggest one reason why feeding might increase CO2 production in these insects. [1] Image 3.3 shows recordings from the experiment. Image 3.3 A Temperature = 18°
  17. June 2024, AS Component 2, Q3(b)(iii) (2 marks): With reference to the partial pressure of carbon dioxide in the tracheoles, explain the reason for the following trends observed in Image 3.3 [2] Trend I: As te
  18. June 2024, AS Component 2, Q4(a)(i) (2 marks): Explain the advantage of closing stomata at night and why the plant is at a disadvantage if the stomata were to close at midday. [2]
  19. June 2024, AS Component 2, Q4(a)(ii) (3 marks): Guard cells in Image 4.1A are turgid. ATP is required for them to achieve this state. Describe the mechanism that enables guard cells to become turgid. [3]
  20. June 2024, AS Component 2, Q4(b)(i) (2 marks): One way to measure the extent of stomatal opening is to calculate the aspect ratio. Aspect ratio (AR) = length of stomatal opening (L) width of stomatal opening
  21. June 2024, AS Component 2, Q4(b)(ii) (2 marks): A student produced a scale drawing of the stoma and guard cells described in (b)(i) and drew a line to represent the length of the stoma (L). This line measured
  22. June 2024, AS Component 2, Q4(b)(iii) (1 mark): Suggest why calculating aspect ratio gives a more precise measurement of the extent to which stomata are open than measuring the width or length of the stoma. [
  23. June 2024, AS Component 2, Q4(b)(iv) (1 mark): The lowest aspect ratio value in Graph 4.2 is greater than 1 With reference to the shape of the stomata in Image 4.1A, suggest why a value of 1 is unlikely. [1]
  24. June 2024, AS Component 2, Q4(c)(i) (2 marks): Use Graph 4.3 to explain how plants living in lower atmospheric CO2 concentrations were adapted for maximum CO2 uptake. [2] Scientists have recorded decreased r
  25. June 2024, AS Component 2, Q4(c)(ii) (2 marks): If atmospheric CO2 concentration continues to increase over time, predict the effect on the stomata of some plant species and suggest why it could cause a reduc
  26. June 2023, Component 1, Q2(a)(i) (1 mark): The tissue layer labelled A in Image 2.1 is the main site of photosynthesis in the leaves of this plant. State the name given to this tissue layer. [1]
  27. June 2023, Component 1, Q2(a)(ii) (2 marks): State one adaptation shown by tissue layer B in Image 2.1. Explain the function of this adaptation. [2]
  28. June 2023, Component 1, Q2(d)(iii) (3 marks): Use Graph 2.4 to conclude which tree was more likely to have been growing under the tree canopy. Use your knowledge of leaf adaptations to give two reasons to e
  29. June 2023, Component 3, Q2(a)(i) (1 mark): State the following for this investigation: [1] the independent variable; ……… ………………………………………… the dependent variable. ……… …………………………………………
  30. June 2023, Component 3, Q2(a)(ii) (2 marks): State two variables that were controlled in this investigation. [2]
  31. June 2023, Component 3, Q2(a)(iii) (2 marks): State two ways in which the student could improve the reliability of the results. [2] Question continued on next page
  32. June 2023, Component 3, Q2(b)(i) (3 marks): Student’s t-test was used to compare the means of the two samples. The null hypothesis was stated as: ‘there was no significant difference between the mean numb
  33. June 2023, Component 3, Q2(b)(ii) (4 marks): Compare your calculated value for t with the figures in Table 2.4 at the 5% level of probability, where the degrees of freedom = (n1 – 1) + (n2 – 1). Explain wh
  34. June 2023, Component 3, Q2(c)(i) (3 marks): Suggest why the increased carbon dioxide concentration resulted in a reduction in stomatal density. [3]
  35. June 2023, Component 3, Q2(c)(ii) (5 marks): A diagram of a stomata from a leaf of grass is shown in Image 2.5. Image 2.5 nucleus cellulose cell wall stomatal pore cytoplasm chloroplast vacuole guard cell
  36. June 2023, Component 3, Q3(c) (2 marks): A respiratory surface is defined as the part of the organism where gaseous exchange takes place between the external air or water and the internal tissues. Comp
  37. June 2023, Component 3, Q3(e)(iv) (2 marks): In their natural habitat the breathing rate of Tibetan wild yaks is much higher than that of humans living at sea level. Explain the difference in the rate of b
  38. June 2023, AS Component 2, Q2(b)(ii) (3 marks): Capillaries have a diameter of 7–10 µm. Describe and explain three effects of the very narrow diameter on gas exchange in a gill capillary. [3]
  39. June 2023, AS Component 2, Q5(a)(i) (1 mark): State one reason, other than protection, why it is an advantage for gas exchange surfaces to be internal in all terrestrial organisms. [1]
  40. June 2023, AS Component 2, Q5(a)(ii) (1 mark): Explain the purpose of ventilation in the lungs of mammals. [1]
  41. June 2023, AS Component 2, Q5(b)(i) (4 marks): Describe how muscles of the thorax, together with the pleural membranes, cause the change in alveolar pressure seen in Graph 5.1 during inspiration. [4] Questio
  42. June 2023, AS Component 2, Q5(b)(ii) (2 marks): Using the data in Graph 5.2 calculate the total volume of air inspired in one minute when this individual is breathing normally at rest. [2]  Total volume insp
  43. June 2023, AS Component 2, Q5(b)(iii) (1 mark): The percentage of carbon dioxide in exhaled air is lower than in alveolar air. Explain why. [1]
  44. June 2023, AS Component 2, Q5(b)(iv) (1 mark): Exhaled air has a slightly higher percentage of nitrogen than inhaled air despite this gas being inert in mammals. Use the information in Table 5.3 to suggest a
  45. June 2023, AS Component 2, Q5(c) (2 marks): Exposure to cigarette smoke has been shown to have a damaging effect on the lungs and reduce respiratory efficiency. Images 5.4 A and B show two electron microg
  46. June 2022, Component 3, Q2(a)(i) (2 marks): The surface area of the Gromia from the Arabian sea was 20 096 mm2 and the volume was 296 947 mm3. Calculate the surface area to volume ratio for this organism.
  47. June 2022, Component 3, Q2(a)(ii) (1 mark): State whether the Gromia discovered in the Bahamas would have a larger or smaller surface area : volume ratio than the Arabian Gromia. Explain your answer. [1]
  48. June 2022, Component 3, Q2(a)(iii) (2 marks): Explain why most single-celled organisms do not need a specialised gas exchange surface. [2]
  49. June 2022, Component 3, Q2(b)(i) (2 marks): Explain the reason for the movement of the gills. [2]
  50. June 2022, Component 3, Q2(b)(ii) (2 marks): In humans, oxygen binds to haemoglobin in order to be transported to respiring cells. Suggest why terrestrial insects do not require haemoglobin. [2]
  51. June 2022, Component 3, Q5(a)(i) (3 marks): The student counted 9 stomata in this field of view. The diameter of the field of view is 0.18 mm. Using this information, calculate the number of stomata per m
  52. June 2022, Component 3, Q5(a)(ii) (2 marks): State two ways in which the student could improve their confidence in the results. [2]
  53. June 2022, Component 3, Q5(b)(i) (2 marks): Using the information given explain why there are no stomata in location X. [2] Tillandsia punctulata, a bromeliad species, lives high in the canopy layer of th
  54. June 2022, Component 3, Q5(b)(ii) (3 marks): Using all the information provided, suggest why this arrangement of trichome plates and stomata is an adaptation for survival in the exposed conditions of the u
  55. June 2022, Component 3, Q5(c) (3 marks): It has been predicted that atmospheric carbon dioxide concentrations will increase to 560 ppm (parts per million) by the year 2050. This is 160 ppm higher than
  56. June 2022, AS Component 2, Q3(a)(i) (2 marks): Using a light microscope, 21 stomata were counted in the area. Use this number to calculate the number of stomata per mm2. [2] Number of stomata = per mm2
  57. June 2022, AS Component 2, Q3(a)(ii) (4 marks): Some of the stomata shown in Image 3.1 are open. Explain the mechanism of stomatal opening which allows gas exchange to take place. [4]
  58. June 2022, AS Component 2, Q3(b)(i) (4 marks): Identify the type of plant which has the type of adaptations shown in Image 3.2 Describe and explain three adaptations shown in Image 3.2 which reduce the loss
  59. June 2022, AS Component 2, Q3(b)(ii) (1 mark): Suggest why the method used to obtain the impression in Image 3.1 would not be a suitable technique to measure stomatal density in the leaf shown in Image 3.2 
  60. June 2022, AS Component 2, Q3(b)(iii) (1 mark): Suggest how the method used to obtain the impression of the stomata in Image 3.1 may need to be modified if using a hydrophyte leaf. [1]
  61. June 2022, AS Component 2, Q4(a)(i) (2 marks): Complete the risk assessment below for the main hazard in the fish head dissection. [2] Hazard Risk Control measure
  62. June 2022, AS Component 2, Q4(a)(ii) (4 marks): Explain four ways in which the gills are adapted for gas exchange. [4]
  63. June 2022, AS Component 2, Q4(b)(i) (1 mark): Using evidence from Table 4.2, identify which graph (A – D) shows blood and water flow in the: [1] Salmon Shark
  64. June 2022, AS Component 2, Q4(b)(ii) (1 mark): Add arrows to the two graphs chosen in (b)(i) to identify the direction of blood and water flow. [1]
  65. June 2022, AS Component 2, Q4(b)(iii) (3 marks): Explain why the salmon is more efficient than the shark in absorbing oxygen from the water passing over the gills. [3]
  66. June 2022, AS Component 2, Q4(c) (3 marks): The ventilation rate in salmon can be determined by counting the number of times the operculum opens and closes per minute. In one experiment, the ventilation r
  67. Autumn 2021, Component 1, Q3(c)(ii) (2 marks): At high wind speeds stomata close. Explain one advantage and one disadvantage of this response to the plant. [2]
  68. Autumn 2021, Component 3, Q2(b)(vi) (5 marks): I. Cadmium has been found to interfere with potassium ion movement in plant cells. Using your knowledge of stomatal opening, suggest an explanation for the resu
  69. Autumn 2021, Component 3, Q3(a) (2 marks): Explain how this causes an increase in the lung volume. [2] The DLCO gas transfer test is used in hospitals to measure the ability of the lungs to exchange gase
  70. Autumn 2021, Component 3, Q3(b) (1 mark): Suggest why carbon monoxide gas is used even though it can be toxic. [1]
  71. Autumn 2021, Component 3, Q3(c)(i) (2 marks): Using image 3.1, explain why the DLCO is higher than 80 % in people who suffer from emphysema. [2]
  72. Autumn 2021, Component 3, Q3(c)(ii) (2 marks): Suggest the effect of an increased blood flow through the lung capillaries on the value of DLCO. Explain your answer. [2]
  73. Autumn 2021, AS Component 2, Q1(a)(i) (1 mark): Name structures A, B and C shown in image 1.1. [1] A B C Image 1.2 shows a transverse section of a human trachea. Image 1.2 Magnification ×8
  74. Autumn 2021, AS Component 2, Q1(a)(ii) (2 marks): Use the line shown in image 1.2 to calculate the actual diameter of the trachea lumen. [2] Diameter = mm
  75. Autumn 2021, AS Component 2, Q1(b)(i) (5 marks): I. Explain how the volume of the thorax is changed during inspiration. [3] II. With reference to the graphs in image 1.3 and your own knowledge, explain the cha
  76. Autumn 2021, AS Component 2, Q1(b)(ii) (2 marks): During expiration there is a risk of collapse of the alveoli due to the positive pressure. Suggest how the alveoli are adapted to deal with this. [2]
  77. Autumn 2021, AS Component 2, Q6 (9 marks): Using the information in Image 6.1 and your knowledge of gas exchange in organisms, explain how Paramecium caudatum is adapted for gas exchange. Explain the ada
  78. Autumn 2020, Component 1, Q1(e)(i) (3 marks): Calculate the surface area : volume ratio of a Prochlorococcus cell which has a radius of 0.3 μm. Express your ratio to the nearest whole numbers. [3] Surface a
  79. Autumn 2020, Component 1, Q1(e)(ii) (3 marks): With reference to the size of the organism, explain how Prochlorococcus is able to gain sufficient minerals from nutrient poor waters. [3]
  80. Autumn 2020, Component 3, Q1(c)(i) (1 mark): As the penguin breathes in, the air passes over bony plates which have capillaries very close to the surface. Suggest how this helps to warm the inspired air. [
  81. Autumn 2020, Component 3, Q1(c)(ii) (3 marks): With reference to images 1.3 and 1.4, explain two features of the gas exchange system of the penguin that make it far more efficient than the gas exchange syste
  82. Autumn 2020, Component 3, Q1(c)(iii) (3 marks): Explain how the direction of blood flow in the capillaries further increases the efficiency of gas exchange. [3]
  83. Autumn 2020, Component 3, Q7 (9 marks): Table 7.1 shows information for several species of fish found in the Amazon River in Brazil. Table 7.1 Mean surface Mean Mass / Genus area of gills / Behaviour
  84. Autumn 2020, AS Component 2, Q1(a)(i) (1 mark): State precisely where gas exchange takes place in the tracheal system. [1]
  85. Autumn 2020, AS Component 2, Q1(a)(ii) (2 marks): One problem facing terrestrial animals like insects is water loss. State two adaptations of the insect tracheal system to reduce water loss. [2]
  86. Autumn 2020, AS Component 2, Q1(a)(iii) (2 marks): Image 1.2 is an electron photomicrograph which shows the detail of the insect tracheae. Image 1.2 10 μm Use the scale bar in image 1.2 to calculate the magnific
  87. Autumn 2020, AS Component 2, Q1(b)(i) (2 marks): State two factors that would need to be controlled during the experiment. [2]
  88. Autumn 2020, AS Component 2, Q1(b)(ii) (2 marks): Explain how abdominal movements are linked to ventilation in the insect. [2]
  89. Autumn 2020, AS Component 2, Q1(b)(iii) (2 marks): Plot the mean data from the experiment as a bar graph on the graph paper below  [2]
  90. Autumn 2020, AS Component 2, Q1(b)(iv) (4 marks): Describe and explain the trend shown by the data. [4]
  91. June 2019, Component 2, Q5(f) (2 marks): Explain the purpose of treating premature babies with surfactants. [2]
  92. June 2019, Component 3, Q1(a)(i) (2 marks): Label figure 1.1 using the letters A and B to show the position of the following: A the main tissue responsible for photosynthesis [1] B the tissue that transpo
  93. June 2019, Component 3, Q1(a)(ii) (3 marks): Conclude whether the leaf shown in figure 1.1 is from a hydrophyte or a xerophyte. Identify two adaptations that support your conclusion. [3] Type of plant: Ada
  94. June 2019, Component 3, Q5(a)(i) (3 marks): Explain how each of the stages stated below enables a bony fish to ventilate its gills. [3] I. mouth opens and floor of buccal cavity lowered II. mouth closes a
  95. June 2019, Component 3, Q5(a)(ii) (3 marks): Explain how in a mammal, the ribcage, diaphragm and pleural membranes are involved in lowering the pressure in the alveoli to below atmospheric pressure during
  96. June 2019, Component 3, Q5(b)(i) (2 marks): Identify the following variables for this experiment: [2] independent variable: dependent variable:
  97. June 2019, Component 3, Q5(b)(ii) (2 marks): Explain why: I. the warm water and crushed ice were made using water from the tanks; [1] II. the catfish were kept at the experimental temperature for five minu
  98. June 2019, Component 3, Q5(c)(i) (2 marks): It was decided that the observation for Fish 1 at 14 °C (in bold) was anomalous and was not included in the calculation of the mean at this temperature. With re
  99. June 2019, Component 3, Q5(c)(ii) (4 marks): Using all the information provided, explain why the ventilation rate increased as temperature increased and why these fish are known to gulp air during the summ
  100. June 2019, Component 3, Q5(c)(iii) (2 marks): The welfare of animals must be considered when using them in any experiment. Suggest why the choice of temperatures used in the experiment was not a cause for c
  101. June 2019, Component 3, Q6(b)(i) (2 marks): Calculate the surface area to volume ratio for this organism. Give your answer to one decimal place. [2] Surface area to volume ratio = : 1
  102. June 2019, Component 3, Q6(b)(ii) (2 marks): A spherical organism of the same volume would have a surface area of approximately 25 230 µm2 and a diameter of approximately 90 µm. Explain why it would be dif
  103. June 2019, AS Component 2, Q5(a) (1 mark): Name the structures labelled A and B. [1] A: B:
  104. June 2019, AS Component 2, Q5(b)(i) (2 marks): Explain why earthworms need a respiratory pigment, but insects do not. [2]
  105. June 2019, AS Component 2, Q5(b)(ii) (1 mark): Suggest why having the type of gas exchange system shown in the diagram means that insects are not able to grow as large as animals which have a circulatory sys
  106. June 2019, AS Component 2, Q5(c) (2 marks): Using the line provided on the electron micrograph, calculate the diameter of the insect tracheole in the electron micrograph, given that the magnification of t
  107. June 2019, AS Component 2, Q5(d)(i) (3 marks): Explain how a thin gas exchange surface and high blood pressure help a tuna to maximise its rate of gas exchange. [3]
  108. June 2019, AS Component 2, Q5(d)(ii) (3 marks): Tuna must swim continuously. Explain why this is essential. [3] Another adaptation found in tuna is that they are able to maintain a core body temperature sever
  109. June 2019, AS Component 2, Q5(e) (2 marks): The tuna’s heat exchanger employs a counter-current flow mechanism. Explain how such an arrangement helps to maximise the rate of heat exchange. [2]
  110. June 2019, AS Component 2, Q6 (9 marks): The three photomicrographs below show three types of angiosperm leaf adapted to different environmental conditions. Photomicrograph A Photomicrograph B Photomic
  111. June 2018, Component 3, Q1(a)(i) (2 marks): Describe two ways that an oxygen concentration gradient is maintained between alveolar air and blood. [2]
  112. June 2018, Component 3, Q1(a)(ii) (1 mark): Explain how the information in the diagram shows that A is the venous end of the pulmonary capillary. [1]
  113. June 2018, Component 3, Q1(b)(i) (1 mark): Name the tissue labelled X on the diagram. [1]
  114. June 2018, Component 3, Q1(b)(ii) (3 marks): Explain why the rate of gas exchange between the air spaces of the leaf and the leaf tissues is lower than between the alveoli and the blood of a mammal. [3]
  115. June 2018, AS Component 2, Q3(a) (3 marks): Use the photomicrographs to explain why less water vapour is lost through the stomata of Pinus sp. than through the stomata of Ligustrum sp. . [3]
  116. June 2018, AS Component 2, Q3(b)(i) (4 marks): Describe how the investigation would have been carried out. [4]
  117. June 2018, AS Component 2, Q3(b)(ii) (3 marks): Calculate the stomatal density of this part of the leaf. The diameter of the field of view of the microscope is 1mm. Give the answer to two decimal places. [3]
  118. June 2018, AS Component 2, Q3(b)(iii) (1 mark): Suggest why the method used would not be suitable for calculating the stomatal density of Pinus leaves. [1]
  119. June 2018, AS Component 2, Q3(c) (2 marks): The table below shows the mean number of stomata on the upper and lower surface of leaves from two species of plant. Mean number of stomata / cm2 Species Upper
  120. June 2018, AS Component 2, Q4(a)(i) (2 marks): Calculate the magnification of the photograph. [2] Magnification =
  121. June 2018, AS Component 2, Q4(a)(ii) (2 marks): Explain how a feature visible in the photograph ensures that the trachea can function effectively during inspiration. [2]
  122. June 2018, AS Component 2, Q4(b) (3 marks): The graph below shows how the air pressure changes in the alveoli during ventilation of the lungs. Inspiration Expiration +2 +1 air pressure in alveolus /a.u. a
  123. June 2018, AS Component 2, Q4(c)(i) (3 marks): I. Describe and explain the change in the partial pressure of oxygen in the blood as it passes along the pulmonary capillaries. [2] II. What conclusion could be
  124. June 2017, Component 3, Q1(a) (3 marks): Describe and explain the common adaptations of the gas exchange surfaces found in fish and mammals. [3] The graph below shows how the metabolic rates of three d
  125. June 2017, Component 3, Q1(b)(i) (1 mark): Describe the general relationship between body mass and metabolic rate. [1]
  126. June 2017, Component 3, Q1(b)(ii) (2 marks): The body temperature of cold-blooded animals, e.g. fish, varies with the temperature of the environment. Suggest why warm-blooded animals which have a constant
  127. June 2017, Component 3, Q1(c)(i) (1 mark): Explain the advantage to the insect of closing the spiracles. [1]
  128. June 2017, Component 3, Q1(c)(ii) (1 mark): Suggest a role of the air sacs. [1]
  129. June 2017, Component 3, Q1(c)(iii) (1 mark): Explain the advantage to the insect of having a ventilation system. [1]
  130. June 2017, Component 3, Q1(d)(ii) (3 marks): Identify organelles X in the diagram on page 5 and explain why they are found close to the tracheoles. [3]
  131. June 2017, Component 3, Q2(a)(i) (3 marks): Outline a method by which the density of stomata could have been determined. [3]
  132. June 2017, Component 3, Q2(a)(ii) (2 marks): The plants used in the investigation were grown either under 100 W m–2 or 20 W m–2 light sources for 8 hours each day at 20°C. State two other environmental fac
  133. June 2017, Component 3, Q2(b)(i) (3 marks): Using the table below, calculate the standard deviation for the density of stomata on the lower leaf surface at 100 W m–2. Enter the standard deviation into the
  134. June 2017, Component 3, Q2(b)(ii) (3 marks): What information do the standard deviations shown in the table of results opposite provide regarding the reliability of the results of this experiment? [3]
  135. June 2017, Component 3, Q2(b)(iii) (3 marks): To what extent do these results support the hypothesis stated in (b)? [3]
  136. June 2017, Component 3, Q2(b)(iv) (1 mark): Based on these results, suggest an alternative hypothesis for the effect of light intensity on stomatal density in tomato plants. [1]
  137. June 2017, AS Component 2, Q6 (9 marks): Tubifex worms have a similar structure to earthworms. They are one of the few multi-cellular organisms that can survive in heavily polluted water which has low
  138. June 2016, AS Component 2, Q7 (9 marks): Axolotls are slow moving animals that live under water. They are sometimes called Mexican Walking Fish, but they are not fish they are amphibians. Axolotls have

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