Microscopy

Question 1

What do light microscopes use and let us see?

Answer 1

They use light and lenses to form an image of a specimen and magnify it. They let us see individual cells and large subcellular structures e.g nuclei

Question 2

What do electron microscopes use and let us see?

Answer 2

They use electrons to form an image. Thy let us see much smaller things in more detail e.g the internal structure of mitochondria and chloroplasts, even ribosomes and plasmids

Question 3

What’s the formula for magnification?

Answer 3

Magnification = image size /real size

Question 4

Rearrange the equation to work out the image size and real size

Answer 4

Image size = magnification × real size
Real size = image size / magnification

Question 5

Practical) How to preparea slide to view onion cells?

Answer 5

1. Add a drop of water to the middle of a clean slide
2. Cut up an onion and separate it out into layers. Use tweezers to peel off some epidermal tissue from the bottom of one of the layers
3. Using the tweezers, place the epidermal tissue into the water on the slide
4. Add a drop of iodine solution(A stain)
5. Place a cover slip on top. To do this, stand the cover slip upright on the slide, next to the water droplet. Then carefully tilt and lower it so it cobers the specimen. Try not to get air bubbles under there - they’ll obstruct your view of the specimen

Question 6

Practical) How to use a light microscope?

Answer 6

1. Clop the slide youve prepared onto the stage
2. Select the lowest-powered objective lens
3. Use the coarse adjustment knob to move the the stage up to jist below the objectice lens
4. Look down the eyepeice, until the image is roughly in focus
5. Adjust the focus with the fine adjustment knob, until you get a clear image
6. If u need to see the slide with fmgreater magnification , swap to a higher-powered objectice lens and refocus