What do microscopes let us do?
Let’s us see things that we can’t see with the naked eye.
What is definition of resolution?
The ability to distinguish between two points that are close together.
What is the difference between electron and light microscope?
Light microscope as lower magnification/lower resolution. Electron has higher magnification/higher resolution.
What can we see in electron microscopes that can’t be seen in light microscopes?
Mitochondria,chloroplasts, ribosomes and plasmids. Light microscopes can only see large structures like nuclei/vacuole.
I = M R
A specimen is 50µm wide. Calculate width of image under a magnification of ×100. Give your answer in mm.
50 = 0.05 mm
0.05 x 100 = 5mm.
R = I/M
A cell is magnified ×400 and the image size of the cell is 2 mm.
Calculate the real size of the cell.
Give your answer in micrometres (µm).
2 = 2000µm.
2000/400 = 5µm.
How do you prepare a slide?
-Add a drop of water
-Cut up an onion into layers. Use tweezers to pull some epidermal tissue from the bottom of the layers.
-Using tweezers,place your epidermal tissue into the water on the slide.
-Add a drop of iodine solution. Iodine solution is a stain. Stains are used to highlight objects in a cell by adding color to them.
-Place a cover slip (square of thin transparent glass) on top. To do this, stand the cover slip upright next to the water droplet. Then carefully tilt and lower it so it covers the specimen. Try not to get any air bubbles under there – they’ll obstruct your view of the specimen.
How do you use a light microscope?
-Clip the slide you prepared onto the stage.
-Select the lowest-power objective lens.
-Use the coarse adjustment knob to move the stage up just below the objective lens.
-Look down the eyepiece. Use coarse adjustment knob until the image is roughly in focus.
-Adjust the focus with the fine adjustment knob, until you get a clear image of what’s on the slide.
-If you need to see with a greater magnification, sap to a higher power objective lens.
How do you draw your observation?
-Draw what you see under the microscope using a pencil with a sharp point.
-Make sure your drawing takes up at least half the space available and that it’s drawn in clear,unbroken lines.
-Your drawing should not contain coloring or shading.
-If you are drawing cells, subcellular structures should be drawn in proportion.
-Remember to include a title of what your observing and write down magnification under.
-Label important features of the drawing.
