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Biology_A-level_Cie

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  1. 1-1-the-microscope-in-cell-studies
    5 主题
  2. 1-2-cells-as-the-basic-units-of-living-organisms
    5 主题
  3. 2-1-testing-for-biological-molecules
    3 主题
  4. 2-2-carbohydrates-and-lipids
    8 主题
  5. 2-3-proteins
    6 主题
  6. 2-4-water
    2 主题
  7. 3-1-mode-of-action-of-enzymes
    5 主题
  8. 3-2-factors-that-affect-enzyme-action
    8 主题
  9. 4-1-fluid-mosaic-membranes
    4 主题
  10. 4-2-movement-into-and-out-of-cells
    12 主题
  11. 5-1-replication-and-division-of-nuclei-and-cells
    6 主题
  12. 5-2-chromosome-behaviour-in-mitosis
    2 主题
  13. 6-1-structure-of-nucleic-acids-and-replication-of-dna
    4 主题
  14. 6-2-protein-synthesis
    5 主题
  15. 7-1-structure-of-transport-tissues
    4 主题
  16. 7-2-transport-mechanisms
    7 主题
  17. 8-1-the-circulatory-system
    7 主题
  18. 8-2-transport-of-oxygen-and-carbon-dioxide
    5 主题
  19. 8-3-the-heart
    4 主题
  20. 9-1-the-gas-exchange-system
    6 主题
  21. 10-1-infectious-diseases
    3 主题
  22. 10-2-antibiotics
    3 主题
  23. 11-1-the-immune-system
    4 主题
  24. 11-2-antibodies-and-vaccination
    6 主题
  25. 12-1-energy
    5 主题
  26. 12-2-respiration
    11 主题
  27. 13-1-photosynthesis-as-an-energy-transfer-process
    8 主题
  28. 13-2-investigation-of-limiting-factors
    2 主题
  29. 14-1-homeostasis-in-mammals
    8 主题
  30. 14-2-homeostasis-in-plants
    3 主题
  31. 15-1-control-and-coordination-in-mammals
    12 主题
  32. 15-2-control-and-coordination-in-plants
    3 主题
  33. 16-1-passage-of-information-from-parents-to-offspring
    5 主题
  34. 16-2-the-roles-of-genes-in-determining-the-phenotype
    7 主题
  35. 16-3-gene-control
    3 主题
  36. 17-1-variation
    4 主题
  37. 17-2-natural-and-artificial-selection
    7 主题
  38. 17-3-evolution
    2 主题
  39. 18-1-classification
    5 主题
  40. 18-2-biodiversity
    7 主题
  41. 18-3-conservation
    6 主题
  42. 19-1-principles-of-genetic-technology
    11 主题
  43. 19-2-genetic-technology-applied-to-medicine
    4 主题
  44. 19-3-genetically-modified-organisms-in-agriculture
    2 主题
  45. 1-1-the-microscope-in-cell-studies
  46. 1-2-cells-as-the-basic-units-of-living-organisms
  47. 2-1-testing-for-biological-molecules
  48. 2-2-carbohydrates-and-lipids
  49. 2-3-proteins
  50. 2-4-water
  51. 3-1-mode-of-action-of-enzymes
  52. 3-2-factors-that-affect-enzyme-action
  53. 4-1-fluid-mosaic-membranes
  54. 4-2-movement-into-and-out-of-cells
  55. 5-1-replication-and-division-of-nuclei-and-cells
  56. 5-2-chromosome-behaviour-in-mitosis
  57. 6-1-structure-of-nucleic-acids-and-replication-of-dna
  58. 6-2-protein-synthesis
  59. 7-1-structure-of-transport-tissues
  60. 7-2-transport-mechanisms
  61. 8-1-the-circulatory-system
  62. 8-2-transport-of-oxygen-and-carbon-dioxide
  63. 8-3-the-heart
  64. 9-1-the-gas-exchange-system
  65. 10-1-infectious-diseases
  66. 10-2-antibiotics
  67. 11-1-the-immune-system
  68. 11-2-antibodies-and-vaccination
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Cells of the blood

  • Blood is a tissue composed of a number of important specialised cells, including:

    • Red blood cells

    • Monocytes

    • Neutrophils

    • Lymphocytes

  • These cells all have distinguishable structures which enable them to be recognised on microscope slides, in photomicrographs and in electron micrographs

Diagram of a red blood cell showing biconcave disc shape, membrane, and haemoglobin. Size is 7.5 µm with no nucleus for more haemoglobin.
Diagram of the structure of a red blood cell
  • Red blood cells contain haemoglobin

    • This is a protein with a quaternary structure that contains haem iron groups which can bind reversibly to oxygen

  • Distinctive features of red blood cells when viewed under a microscope, are their distinctive biconcave disc shape (caused by their lack of nucleus)

Illustration showing a collection of pink and purple circular shapes resembling a microscopic view of red blood cells, scattered on a white background.
Red blood cell micrograph
Diagram of a monocyte with labelled parts: nucleus, cytoplasm, mitochondrion, chromatin, Golgi apparatus, lysosome; diameter 18 μm.
A monocyte is a type of white blood cell
  • Monocytes are identifiable by their size

    • They are the largest of the leukocytes and have a nucleus shaped like a kidney or a bean

  • The nucleus of monocytes tends to appear lighter after staining than other leukocytes

  • The nucleus should appear a light blue colour, while the chromatin inside is distinct and fine

Diagram of a purple-stained monocyte in a blood smear, showcasing lobed nucleus and granulated cytoplasm on a light background with circular patterns.
A micrograph of a monocyte cell
  • Neutrophils are distinguished by their multi-lobed nuclei

  • Up to 70% of all leukocytes are neutrophils

    • This makes them easy to spot on a micrograph

  • The granules of neutrophils typically stain pink or purple-blue

Diagram of a neutrophil cell with labels for multilobed nucleus, glycogen, azurophilic granules, secondary granule, phagosome; diameter 12-14 µm.
A neutrophil is a type of white blood cell
Neutrophil Micrograph
A micrograph of a neutrophil cell
  • Lymphocytes are small leukocytes that are identifiable by their very large nuclei, which typically stains a dark colour

  • Lymphocytes constitute around 20-25% of all leukocytes

  • Lymphocytes are around the size of red blood cells

<img alt=”Diagram of a lymphocyte with labels: endoplasmic reticulum, ribosome, cytoplasm, mitochondrion, large round nucleus; diameter 7-14 micrometres.” data-nimg=”1″ decoding=”async” height=”700″ sizes=”(max-width: 320px) 320w, (max-width: 640px) 640w, (max-width: 960px) 960w, (max-width: 1280px) 1280w, 1920w” src=”https://cdn.savemyexams.com/cdn-cgi/image/f=auto,width=3840/https://cdn.savemyexams.com/uploads/2025/09/28797_httpscdn-savemyexams-comuploads202101lymphocyte.png” srcset=”https://cdn.savemyexams.com/cdn-cgi/image/f=auto,width=16/https://cdn.savemyexams.com/uploads/2025/09/28797_httpscdn-savemyexams-comuploads202101lymphocyte.png 16w, https://cdn.savemyexams.com/cdn-cgi/image/f=auto,width=32/https://cdn.savemyexams.com/uploads/2025/09/28797_httpscdn-savemyexams-comuploads202101lymphocyte.png 32w, https://cdn.savemyexams.com/cdn-cgi/image/f=auto,width=48/https://cdn.savemyexams.com/uploads/2025/09/28797_httpscdn-savemyexams-comuploads202101lymphocyte.png 48w, https://cdn.savemyexams.com/cdn-cgi/image/f=auto,width=64/https://cdn.savemyexams.com/uploads/2025/09/28797_httpscdn-savemyexams-comuploads202101lymphocyte.png 64w, https://cdn.savemyexams.com/cdn-cgi/image/f=auto,width=96/https://cdn.savemyexams.com/uploads/2025/09/28797_httpscdn-savemyexams-comuploads202101lymphocyte.png 96w, https://cdn.savemyexams.com/cdn-c