GCE AQA BIOL - Cells Laboratory Techniques
Unit 3.1 Biology and disease
3.1.3 Substances are exchanged between organisms and their environment by passive or active transport across exchange surfaces. The structure of plasma membranes enables control of the passage of substances across exchange surfaces.Cells
Microscopes 🔬Cells are so small that they need to be seen using microscopes. We can divide microscopes into two main categories, which can be further subdivided:
Light microscopes are the microscopes found in school laboratories for GCE AQA Biology. They use a normal light to illuminate the specimen so that we can see it magnified via a convex lens 🔍.
There are some limitations to using light, that can be overcome by using electron beams instead:
Now that we know what the advantages of using electron microscopes are, let’s examine the principles and limitations behind the two types you will need to know in GCE AQA Biology. 🧫
1. Transmission Electron Microscope Principles
2. Scanning Electron Microscope Principles
Microscope terminologyThere are two terms that you should be careful to distinguish in GCE AQA Biology:
Magnification is how many times the image is bigger than the object.
Resolution/resolving power is the minimum distance apart two objects need to be so that they appear as distinct, separate objects in the image.
How to prepare cells for microscopy 🥼In order to see the individual organelles inside cells clearly, we need to separate them.
Cell fractionation: process of breaking up cells and separating out the organelles inside the cells 🦠
1. Submerge the cells in a special solution 🧪
That's all for today!
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Written by Justine | Biology Specialist @ Tuttee
ReferencesToole, G., & Toole, S. (2015). Aqa biology A level. Oxford: Oxford University Press.Images from
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