Term
| What range of wavelengths is visible light within? |
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Definition
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Term
| How is a light microscope able to magnify an object? |
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Definition
| Increasing the angle of light from the object entering the eye. |
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Term
How can an electron microscope
resolve much smaller structures than a light microscope? |
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Definition
| Electrons have shorter wavelengths than visible light. |
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Term
Which of the following items is likely to be the smallest? Which is the largest?
A peroxisome, a cell nucleus, a mitochondrion, a white blood cell, a chloroplast. |
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Definition
Peroxisome is smallest
White blood cell is largest |
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Term
Which of the following represents the better resolution?
0.2 mm, 0.2 µm, 1 µm, 1 mm, 20 nm |
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Definition
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Term
What is the main advantage of phase contrast microscopy over traditional
light microscopy? |
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Definition
| It produces a clearer image of unstained specimens. |
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Term
Which substance makes up the largest proportion of a typical cell by
weight? |
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Definition
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Term
| What is the main difference between eukaryotic cells and prokaryotic cells? |
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Definition
| Eukaryotic cells contain membrane-bound organelles. |
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Term
| At which size do structures become unable to be seen by the unaided eye? |
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Definition
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Term
| At which size do structures become unable to be seen by a visible light microscope? |
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Definition
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Term
| At which size do structures become unable to be seen by an electron microscope? |
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Definition
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Term
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Definition
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Term
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Definition
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Term
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Definition
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Term
| How many times magnification can you get on a light microscope? |
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Definition
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Term
| What is the light path in a light microscope? |
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Definition
| Light source -> condenser lense -> specimen -> objective lense -> eyepiece lense -> eye |
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Term
| If specimens aren't small or thin enough to be seen in a light microscope, what happens to them so they can? |
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Definition
| They are fixed, cut into thin slices and stained |
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Term
| What are the three types of optics that allow the details of living, unstained cells to be seen? |
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Definition
-Bright field optics (ordinary)
-Phase contrast optics
-Interference contrast optics |
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Term
| How do phase contrast and interference contrast optics provide more detail? |
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Definition
| By exploiting differences in the way light travels through regions of the cell with differing refractive indexes |
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Term
| How is a fluorescence microscope different from a regular light microscope? |
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Definition
| The illuminating light is sent through two sets of filters |
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Term
| What do the two filters in a fluorescence microscope do? |
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Definition
The one nearest the light source only allows through the wavelengths that excite the fluorescent dye
The one nearest the eyepiece only allows the wavelengths emitted when the dye fluoresces. |
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Term
| What is a confocal microscope? |
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Definition
| A specialised type of fluorescence microscope that builds up an image by scanning the specimen with a laser beam |
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Term
| Why does a confocal microscope give a more detailed image than a fluorescence microscope? |
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Definition
| Only the fluorescence from a small part of the specimen is detected, in a fluorescence microscope, fluorescent structures above and below the focal plane make it blurred |
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Term
| What is the path of the electrons in a transmission electron microscope? |
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Definition
| Electron gun -> condenser lense -> specimen -> objective lense -> projector lense -> viewing screen or photographic film |
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Term
| What is the path of the electrons in a scanning electron microscope? |
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Definition
| Electron gun -> condenser lense -> beam deflector -> objective lense -> specimen -> detector |
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Term
| What are the lenses in an electron microscope? |
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Definition
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Term
| What must the specimen be like to be used in a transmission electron microscope? |
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Definition
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Term
| How is contrast increased for a transmission electron microscope? |
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Definition
| By staining the specimen with electron dense heavy metals that locally absorb or scatter electrons, removing them from the beam as it passes through the specimen |
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Term
| What happens in a scanning electron microscope? |
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Definition
| The specimen is scanned by a beam of electrons focused by lenses |
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Term
| What is done to the specimen before it is put in a scanning electron microscope? |
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Definition
| It is coated with a thin film of heavy metal |
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Term
| How is a picture created in a scanning electron microscope? |
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Definition
| The quantity of electrons scattered as the beam hits each part of the specimen is measured by the detector, which builds up an image on a computer screen |
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Term
| What is the main difference between transmission and scanning electron microscopes? |
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Definition
| Scanning electron microscopes build up a 3D image |
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Term
| What controls the size of the image in light microscopy? |
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Definition
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Term
| What is dark field microscopy? |
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Definition
| When the specimen is on a dark background so person can detect small amounts of light |
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Term
| What is dark ground microscopy? |
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Definition
| When light is allowed through certain points so small differences in the refractive index show up |
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Term
| What is the advantage of dark ground microscopy? |
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Definition
| The specimen can be naturally coloured and live due to not needing to be coloured |
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Term
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Definition
| The ability to see two points as separate |
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Term
| How is the resolving power of a microscope measured? |
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Definition
| By calculating half the wavelength of the light/electrons |
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Term
| What is the main advantage of light microscopy? |
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Definition
| Can use a living or dead specimen |
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Term
| What is the main disadvantage of light microscopy? |
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Definition
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Term
| What is the main advantage of fluorescence microscopy? |
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Definition
| Coloured so easy to see organelles |
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Term
| What is the main advantage of transmission electron microscopy? |
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Definition
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Term
| What is the main disadvantage of transmission electron microscopy? |
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Definition
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