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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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Electron micrographs: animal cells

  • Exam questions will not always contain neat diagrams of cellular structures, but may instead present images taken using microscopes

    • Such images are known as micrographs

  • It is possible to identify organelles in micrographs of animal cells on the basis of their shape, location, and size relative to other organelles, e.g.

    • The nucleus will always be the largest organelle

    • Mitochondria are the next largest, and are often cylindrical with a folded inner membrane

      • Note that mitochondria are not always cylindrical, but can also be circular; their shape will depend on their age, and on the angle at which they were sliced during specimen preparation

    • RER will be near the nucleus, and ribosomes can sometime be seen

    • Lysosomes and vesicles will be smaller than mitochondria

Electron micrograph of an animal cell with labelled diagram: rough endoplasmic reticulum, mitochondria, plasma membrane, nucleus, cytoplasm, lysosomes, vesicle.
Exam questions may present micrograph images of cells

Examiner Tips and Tricks

You should be able to describe and interpret photomicrographs, electron micrographs and drawings of typical animal cells.

Electron micrographs: plant cells

  • Plant cell micrographs can be interpreted using the same techniques as animal cells

    • Large, seemingly empty spaces inside cells will be vacuoles

    • The nucleus will be the largest dark region in the cell

    • Chloroplasts are the next-largest organelles, and grana are often visible

Electron micrograph of a plant cell with labelled parts: mitochondria, cell wall, nucleus, vacuole, and chloroplasts, alongside a microscopic view.
Vacuoles and chloroplasts can be easily recognised inside plant cells

Examiner Tips and Tricks

You should be able to describe and interpret photomicrographs, electron micrographs and drawings of typical plant cells.

Structure of animal & plant cells

  • Animal and plant cells have many common structures:

    • Cell surface membrane

    • Cytoplasm

    • Nucleus

    • Mitochondria

    • Rough and smooth endoplasmic reticulum

    • Golgi bodies

    • Vesicles and lysosomes

    • Ribosomes

    • Microtubules

  • Plant cells are larger and more regular in shape than animal cells, and have the following additional structures

    • Cellulose cell wall

    • Large permanent vacuoles

    • Chloroplasts

    • Plasmodesmata

  • The only structures found in animal cells but not plant cells are centrioles and microvilli

animal-cell-structure
Diagram of a plant cell showing labelled parts including nucleus, chloroplast, mitochondrion, vacuole, Golgi body, and cell membrane.
Plant cells have a larger, more regular structure in comparison to animal cells