Electron microscopes Electron microscopes use electrons to form an image This greatly increases the resolution of electron microscopes compared to optical microscopes, giving a more detailed image A beam of electrons has a much smaller wavelength than light, so an electron microscope can resolve distinguish between two objects that are extremely close together Electron microscopes have a maximum resolution of around 0.
Scanning electron microscopes SEMs SEMs scan a beam of electrons across the specimen This beam bounces off the surface of the specimen and the electrons are detected, forming an image This means SEMs can produce three-dimensional images that show the surface of specimens Advantages of SEMs: They can be used on thick or 3-D specimens They allow the external , 3-D structure of specimens to be observed Disadvantages of SEMs: They give lower resolution images less detail than TEMs They cannot be used to observe live specimens unlike optical microscopes that can be used to observe live specimens They do not produce a colour image unlike optical microscopes that produce a colour image.
The high resolution is due to the fact that the laser beam can be focused at a very specific depth You can even see the structure of the cytoskeleton in cells Disadvantages: It is a slow process and takes a long time to obtain an image The laser has the potential to cause photodamage to the cells.
Development of Practical Skills in Biology 1. Download PDF. Join Now Already a member? Log In. New resources. Straight to your inbox. Sign up to our newsletter. Cookies We use cookies to improve your experience on our website. Biological mathematics and problem-solving skills can be fully integrated into teaching and learning. Our new AS Level in Biology A enables students to develop essential knowledge and understanding of different areas of the subject and how they relate to one another, and an appreciation of scientific methods, as well as practical, mathematical, and problem-solving skills.
Date: 20 Jan pm-4pm. Date: 03 Feb pm-4pm. Create a bespoke scheme of work using the extensive range of resources we have provided for each specification. Each specification has been broken down into statements and mapped to individual teaching activities.
A Level AS Level Our new A Level in Biology A allows students to develop relevant practical skills alongside essential knowledge and understanding of a range of biological concepts and scientific methods.
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