This memory aid covers Memory Aid: The MIR Triangle within Cell Biology Practical Investigations for GCSE Biology. Comprehensive practical skills, experimental design, data analysis, microscopy techniques, and scientific methodology in cell biology It is section 14 of 18 in this topic. Use it for quick recall, then test yourself straight afterwards so the memory aid becomes usable in an answer.
Memory Aid: The MIR Triangle
Draw this triangle and memorise it — it appears in almost every biology paper:
[ I ]
[M x R]
Write I (Image size) in the top half of the triangle, and M (Magnification) and R (Real size) side by side in the bottom half.
- Cover I → Image size = M × R
- Cover M → Magnification = I ÷ R
- Cover R → Real size = I ÷ M
Unit conversion reminder:
"Milli to Micro — times by 1000" (1 mm = 1000 µm)
"Micro to Milli — divide by 1000" (1000 µm = 1 mm)
Stain colours mnemonic:
- Iodine = dark blue-Inky black (stains starch and cell walls)
- Methylene blue = blue nucleus (Makes the nucleus visible)
Practice questions for Cell Biology Practical Investigations
When using a light microscope to observe cells, which objective lens should be used first?
Describe how to focus a light microscope on a specimen.