Lesson 3.2.1.3.1

3.2.1.3.1 Microscopy, magnification and cell fractionation Quiz: AQA Biology, Unit 2

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

In partnership with Revision Ninja

Lesson 3.2.1.3.1, Microscopy, magnification and cell fractionation: 20 multiple choice questions for the AQA Biology (7402), Unit 2: Cells, written with Revision Ninja.

Host it live on the board and students join with a game code on their own devices, or revise alone with Free Play. The answers are revealed in the game.

Host this setFree Play

The 20 questions

  1. What is the formula for magnification?

    • Magnification = size of image + size of real object
    • Magnification = size of real object / size of image
    • Magnification = size of image / size of real object
    • Magnification = size of image x size of real object

  2. What is meant by the resolution of a microscope?

    • The brightness of the image that is produced by the light source inside the microscope body
    • The size of the smallest object that can be seen as a single point when viewed under the lens
    • The maximum magnification that the microscope is able to produce while keeping the image in focus
    • The minimum distance between two points that can still be seen as two separate points

  3. Which type of microscope gives the highest resolution?

    • Optical microscope
    • Transmission electron microscope
    • Scanning electron microscope
    • Light microscope with a digital camera

  4. What does a scanning electron microscope mainly show?

    • The three-dimensional surface of a specimen
    • The internal structure of a thin section of a cell
    • Only the nucleus of a cell, stained with a dye
    • Living cells at high resolution in their natural colour

  5. What is the approximate resolution limit of a light microscope?

    • About 20 mm
    • About 200 nm
    • About 0.02 nm
    • About 2 nm

  6. Why is the homogenisation step performed in cell fractionation?

    • To stain the organelles so they can be seen under a microscope with no exceptions
    • To separate the organelles by their density in a gradient
    • To break open the cells and release the organelles into a solution
    • To make the organelles soluble in ethanol

  7. Why is the solution used in cell fractionation kept cold and isotonic?

    • To encourage the organelles to dissolve in the solution so that they can be separated more easily
    • To prevent organelles from being damaged, and to avoid their swelling or shrinking by osmosis
    • To make the organelles denser so that they settle out of solution more quickly in the tube
    • To allow the organelles to synthesise ATP during the separation process in the centrifuge tube

  8. What is the unit conversion for 1 micrometre expressed in nanometres?

    • 100 nm
    • 1000 nm
    • 10000 nm
    • 1 nm

  9. A cell has an image length of 40 mm when viewed at a certain magnification. Its actual length is 0.02 mm. What is the magnification?

    • 4000
    • 200
    • 20
    • 2000

  10. An image of a cell is 16 mm wide at a magnification of x800. What is the actual width of the cell?

    • 0.2 mm
    • 0.002 mm
    • 12.8 mm
    • 0.02 mm

  11. A mitochondrion appears 60 mm long in a micrograph at a magnification of x30000. What is its actual length?

    • 20 micrometres
    • 0.2 micrometres
    • 200 micrometres
    • 2 micrometres

  12. In a centrifuge, which cell component sediments first when a homogenate is spun at a low speed?

    • Ribosomes, which are the lightest components
    • Nuclei and large unbroken cell fragments
    • Mitochondria, which need the highest speed
    • Lysosomes, which have a density lower than water

  13. Why do ribosomes need to be separated by ultracentrifugation at a higher speed than mitochondria?

    • Ribosomes are much smaller than mitochondria, so they need a greater centrifugal force to sediment
    • Ribosomes contain DNA, which makes them heavier than mitochondria
    • Ribosomes are larger than mitochondria, so they need more force to move
    • Ribosomes are membrane-bound, so they stick to the tube and must be spun harder

  14. A light microscope cannot show individual ribosomes clearly. Why?

    • Ribosomes are too heavy to be placed on a slide
    • Ribosomes are smaller than the resolution limit of a light microscope
    • Ribosomes absorb all the light so that no image is produced
    • Ribosomes are colourless and cannot be stained

  15. Why does increasing magnification without increasing resolution produce a less useful image?

    • The image becomes sharper, but the actual object becomes smaller
    • The image becomes smaller and darker, which hides the detail
    • The image becomes larger but blurred, so no additional detail can be seen
    • The image shows more colour, which reduces the detail visible

  16. A student says that doubling the magnification of a light microscope doubles the amount of detail that can be seen. Which evaluation is correct?

    • Correct, because doubling the magnification always doubles the number of organelles that can be seen clearly
    • Correct, because magnification and resolution are the same property of the microscope and always rise together
    • Incorrect, because detail depends on resolution, and beyond the resolution limit more magnification gives only a larger blurred image
    • Incorrect, because magnification has no effect on the image itself, but only changes the brightness of the view

  17. Explain why artefacts can appear in electron micrographs, and how scientists distinguish them from genuine organelles.

    • Artefacts are always organelles that have been stained by the dye, so they must be counted as genuine structures
    • Artefacts come from the preparation process, so they are checked by comparing images prepared in different ways and other evidence
    • Artefacts appear only in living cells that are viewed without any fixing, so they can be avoided by fixing the cell
    • Artefacts are caused by the light source of the microscope, so they can be removed by using a higher magnification

  18. A student claims that a scanning electron microscope shows internal structure better than a transmission electron microscope. Which evaluation is correct?

    • Incorrect, because neither type of electron microscope can produce any usable image of the internal structure of cells
    • Correct, because the scanning electron microscope has a higher resolution than every other type of microscope available
    • Correct, because the scanning electron microscope passes the electron beam through the whole specimen to show the interior
    • Incorrect, because the scanning microscope shows surface detail, whereas the transmission microscope shows internal structure

  19. Explain why the principle of cell fractionation depends on organelles having different densities or sizes.

    • Organelles of different density and size sediment at different rates during centrifugation, so they can be separated into layers
    • Organelles are separated by their colour, which changes at different centrifugal speeds
    • Organelles of the same density all sediment at the same rate, so they can be separated only by staining
    • Organelles are separated by their electric charge, which makes them move in a magnetic field

  20. Explain why a student would not expect to see the internal structure of a living cell in a transmission electron micrograph.

    • The specimen must be thinly sliced, fixed and placed in a vacuum, which kills the cell
    • Living cells cannot be stained, so they show no contrast in an electron micrograph with no exceptions
    • The electron beam is too weak to pass through any cell structure
    • Transmission electron microscopes can only image the outer surface of the cell

All AQA Biology quizzes