Back to AI Flashcard MakerBiology /OCR Biology A - 2.1.1 - Cell Structure Part 1
What does a microscope allow us to do
Magnify an object many times
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Key Terms
Term
Definition
What does a microscope allow us to do
Magnify an object many times
Eyepiece graticule
Circular disk that fits onto the eyepiece and contains a tiny ruler with equal divisions on it
Stage micrometer
Usually 1-100nm long with 100 divisions on it. This sits on the stage of the microscope and is used to calibrate the eyepiece graticule
Why do we need a stage micrometer to calibrate the eyepiece graticule
The eyepiece graticule remains constant no matter what magnification the cells are used at
What are the two types of objective lens in a compound light microscope
High power
Low power
What instrument was used before the first microscope
Magnifying glasses
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| Term | Definition |
|---|---|
What does a microscope allow us to do | Magnify an object many times |
Eyepiece graticule | Circular disk that fits onto the eyepiece and contains a tiny ruler with equal divisions on it |
Stage micrometer | Usually 1-100nm long with 100 divisions on it. This sits on the stage of the microscope and is used to calibrate the eyepiece graticule |
Why do we need a stage micrometer to calibrate the eyepiece graticule | The eyepiece graticule remains constant no matter what magnification the cells are used at |
What are the two types of objective lens in a compound light microscope | High power
Low power |
What instrument was used before the first microscope | Magnifying glasses |
What type of microscope did Robert Hooke invent | A compound light microscope |
What is the main feature of compound microscopes | They have 2 types of lenses, the eyepiece and objective lenses |
In what year was the electron microscope invented in | 1931 |
What is an advantage of an electron microscope | Capable for far greater resolution and magnification of 1 mil. |
What is a disadvantage of electron microscope | Living specimens are destroyed by high dose of radiation |
Metric equivalent of decimetre, dm | 1 x 10^-1 m |
Metric equivalent of millimetre, mm | 1 x 10^-3 m |
Metric equivalent of micro metre | 1 x 10^-6 m |
Metric equivalent of nanometre, nm | 1 x 10^-9 m |
What does the amount of detail seen through a microscope depend on | The resolving power of the microscope |
Resolving power | The smallest separation at which two separate objects can be distinguished (or resolved) |
What is the resolving power of a microscope ultimately limited by | The wavelength of light |
What is the wavelength of light | 400-600nm |
Why do some microscopes have blue filters | Blue has the shortest wavelength of visible light and to improve the resolving power a shorter wavelength of light is needed |
Definition of magnification | How much bigger a sample appears to be under the microscope than it’s in real life |
Definition of resolution | Ability to distinguish between two points on an image i.e. the amount of detail |
What is the resolution of an image limited by and why | The wavelength of radiation used to view the sample
When objects in the specimen are smaller than half the wavelength of the radiation being used, they don’t interrupt the waves, and so aren’t detected |
What is the wavelength of light much larger than | The wavelength of electrons, so the resolution of the light microscope is a lot lower |
How does using a microscope with a more powerful magnification affect the resolution | It does not
It will increase the size of the image but objects closer than 200nm will still only be seen as one point |