Cell Biology - Microscopy 18-20

Question 1

what are the two different microscopes

Answer 1

1) light microscope
2) electron microscope

Question 2

what is a light microscope
2 points

Answer 2

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

Question 3

what is an electron microscope
3 points

Answer 3

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

Question 4

what is the formula for magnification

Answer 4

magnification= image size / real size

Question 5

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

Answer 5

1000µm = 1mm

Question 6

what is 0.0025 in standard form

Answer 6

2.5 x 10^-3

Question 7

what are the parts of a light microscope
6 points

Answer 7

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

Question 8

label a light microscope

Answer 8

look at page 19 of AQA biology book

Question 9

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

Answer 9

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

Question 10

what is a stain

Answer 10

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

Question 11

what magnification should you always start with and why

Answer 11

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

Question 12

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

Answer 12

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

Question 13

what are the rules for drawing microscopic observations
6 points

Answer 13

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