Scale, Size and Magnification
Part of Cell Structure · GCSE GCSE Biology revision
This deep dive covers Scale, Size and Magnification within Cell Structure for GCSE Biology. Cell theory, prokaryotic and eukaryotic cells, animal and plant cell organelles, bacterial cells, specialized cells, and microscopy It is section 10 of 17 in this topic. Use this deep dive to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 10 of 17
Practice
31 questions
Recall
25 flashcards
📏 Scale, Size and Magnification
Key Definitions:
- Magnification: How many times larger an image appears compared to the actual object
- Resolution: The ability to distinguish between two separate points
- Real size: The actual size of the specimen
The Magnification Formula:
Magnification = Image Size ÷ Real Size
Real Size = Image Size ÷ Magnification
Image Size = Magnification × Real Size
Units and Scale:
| Unit | Symbol | Equivalent | Used for |
|---|---|---|---|
| Metre | m | 1 m | Whole organisms |
| Millimetre | mm | 1 × 10⁻³ m | Small organisms |
| Micrometre | μm | 1 × 10⁻⁶ m | Cells and organelles |
| Nanometre | nm | 1 × 10⁻⁹ m | Molecules |
Typical Cell Sizes:
- Bacterial cells: 1-5 μm
- Animal cells: 10-30 μm
- Plant cells: 10-100 μm
- Egg cells: 100-150 μm (largest human cell)
Quick Check: A cell is 50 μm in real size. Under ×400 magnification, what is the image size?
Image size = Magnification × Real size = 400 × 50 μm = 20,000 μm = 20 mm. Remember to check your units — the question may ask you to give the answer in mm.
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Read this section alongside the surrounding pages in Cell Structure. That gives you the full topic sequence instead of a single isolated revision point.
Practice Questions for Cell Structure
Which part of the cell contains DNA and controls the cell's activities?
Describe the structure and function of chloroplasts.
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