Lesson T1.1.1

T1.1.1 Cells and light microscopy Quiz: KS3 Biology, Unit 1

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson T1.1.1, Cells and light microscopy: 20 multiple choice questions for the KS3 Biology (National Curriculum), Unit 1: Structure and function of living organisms, written with Revision Ninja.

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The 20 questions

  1. Which structure is the basic building block of all living organisms?

    • The organ system
    • The tissue
    • The organ
    • The cell

  2. Which part of a light microscope is the one you look through?

    • The objective lens
    • The coarse focus knob
    • The eyepiece lens
    • The stage clip

  3. What does the stage of a light microscope hold in place?

    • The slide carrying the specimen
    • The eyepiece that magnifies the image
    • The coarse focus knob for moving it
    • The lamp that lights the specimen

  4. What does the diaphragm of a light microscope control?

    • The amount of light passing through the specimen
    • The strength of the magnification of the eyepiece lens
    • The colour and thickness of the stain used on the specimen
    • The distance between the slide and the objective lens

  5. Why is a stain such as iodine often added to cells before viewing them?

    • To make cell structures easier to see
    • To stop the specimen drying out
    • To kill all bacteria on the slide
    • To increase the magnification of the lens

  6. A microscope has an eyepiece lens of x10 and an objective lens of x40. What is the total magnification?

    • x50
    • x30
    • x4000
    • x400

  7. Which objective lens should you use first when looking for a specimen on a slide?

    • The highest-power objective lens
    • The lowest-power objective lens
    • The middle-power objective lens
    • Whichever lens gives the brightest view

  8. Why should a cover slip be lowered onto a specimen at an angle?

    • To make the stain spread faster across the slide
    • To stop the cover slip from scratching the lens
    • To make the slide easier to store afterwards
    • To avoid trapping air bubbles under it

  9. An image of a cell measures 5 cm across under a total magnification of x100. What is the real width of the cell?

    • 5.5 cm, or 55 mm, found by adding ten to the image size
    • 0.05 cm, or 0.5 mm
    • 50 cm, or 500 mm, found by multiplying the image size by ten
    • 0.5 cm, or 5 mm, found by dividing the image size by ten

  10. Convert 0.5 mm into micrometres (µm).

    • 0.005 µm
    • 5000 µm
    • 500 µm
    • 50 µm

  11. Which is the correct way to draw a cell seen under a microscope?

    • Draw in ink and shade the nucleus darkly to show its position clearly
    • Sketch only the outline using a ruler to keep the drawing neat
    • Use coloured pens and shade the whole cell to show its detail clearly
    • Use a sharp pencil, single clear lines, and no shading

  12. What does magnification of a microscope mean?

    • How sharp the image looks when it is viewed through the eyepiece lens
    • How many times larger the image is than the real specimen
    • How many cells can be seen at once in one field of view of the lens
    • How much light the lamp produces when the microscope is switched on

  13. Which unit is commonly used to measure the size of very small cells?

    • Millilitre
    • Kilometre
    • Micrometre
    • Kilogram

  14. Why do school labs use light microscopes to study cells?

    • They can show the inside of a whole human body in full colour detail
    • They let pupils see cells and some of their parts
    • They show individual atoms in clear detail with no magnification at all
    • They work without any light source at all, so specimens need no lamp

  15. A cell appears 4 cm across at x200 magnification. What is its actual width in mm?

    • 20 mm
    • 2 mm
    • 0.02 mm
    • 0.2 mm

  16. A cell is 0.02 mm across. How many micrometres is that?

    • 0.2 µm
    • 2 µm
    • 20 µm
    • 200 µm

  17. What happens to the field of view when the magnification is increased from x100 to x400?

    • The field of view gets larger
    • The field of view stays the same
    • The field of view gets smaller
    • The field of view doubles in size

  18. Why does a very high magnification not always reveal more detail with a light microscope?

    • Light microscopes have limited resolution, so fine detail is lost
    • The eyepiece lens always blocks the finest structures from being seen
    • Stains remove detail from the cell image as they are added to the slide
    • Magnification always adds the same amount of detail at any level of power

  19. A cell image is 10 cm wide and the real cell is 0.1 mm wide. What is the magnification?

    • x10
    • x100
    • x10000
    • x1000

  20. Which order correctly describes preparing and viewing a specimen?

    • Add cover slip first, then place specimen, then stain, then focus on highest power
    • Place specimen on slide, add stain, lower cover slip, focus on lowest power
    • Stain the eyepiece, place the slide on the stage, then lower the stage and focus
    • Focus on highest power first, then place specimen on slide, then add the stain

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