Cell Biology - Microscopy 18-20 Flashcards

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1
Q

what are the two different microscopes

A

1) light microscope
2) electron microscope

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2
Q

what is a light microscope
2 points

A

1) they use light and lenses to form an image and magnify it
2) they let us see individual cells and large subcellular structures

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3
Q

what is an electron microscope
3 points

A

1) they use electrons instead of light to form an image
2) they have a much higher magnification and a higher resolution
3) they let us see much smaller things in more detail like ribosomes and plasmids

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4
Q

what is the formula for magnification

A

magnification= image size / real size

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5
Q

what is the conversion between micrometres (µm) to millimetres (mm)

A

1000µm = 1mm

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6
Q

what is 0.0025 in standard form

A

2.5 x 10^-3

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7
Q

what are the parts of a light microscope
6 points

A

1) eyepiece lens
2) high and low power objectives lenses
3) coarse adjustment knob
4) fine adjustment knob
5) the stage
6) the light

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8
Q

label a light microscope

A

look at page 19 of AQA biology book

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9
Q

how would i prepare a slide to view onion cells
5 steps

A

1) add a drop of water to the middle of a clean slide
2) cut up an onion and separate them into layers, use tweezers to peel of some epidermal tissue
3) using the tweezers place epidermal tissue onto the slide
4) add a drop of iodine solution as a stain to the tissue
5) place a cover slip on top of the tissue making sure no air bubbles underneath

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10
Q

what is a stain

A

stains are used to highlight objects in a cell by adding colour to them

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11
Q

what magnification should you always start with and why

A

the lowest magnification so you have the highest field of view, so it’s easier to locate specimen

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12
Q

How do you use a light microscope to look at your slide
6 points

A

1) clip the slide you have prepared onto the stage
2) select the lowest-powered objective lens
3) use the coarse adjustment knob to move the stage up to just below the objective lens
4) look down the eyepiece, use the coarse adjustment knob to move the stage down until the image is roughly in focus
5) adjust the fine focus adjustment knob, until you get a clear image of what’s on the slide
6) if you need to see the slide with greater magnification swap to a higher-powered objective lens and refocus

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13
Q

what are the rules for drawing microscopic observations
6 points

A

1) take up at least half the space available
2) drawn with clear, unbroken lines
3) the drawing should not include colouring or shading
4) subcellular structures should be drawn in proportion
5) include a title and magnification
6) label feature using straight uncrossed lines

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