Cell Biology: Microscopes Required Practical & Microscopy

Question 1

How do you use a light microscope to view a prepared slide?

Answer 1

1. Clip the prepared slide 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 bring the image roughly into focus.
5. Adjust the focus with the fine adjustment knob, until you get a clear image.

Question 2

What is the coarse adjustment knob on a light microscope used for? (its used twice)

Answer 2

To move the stage up to just below the objective lens before looking down the eyepiece to focus.
Also used while looking down the eyepiece to bring the image roughly into focus.

Question 3

What is the fine adjustment knob used for when using a light microscope?

Answer 3

• after using the coarse adjustment knob
• while looking down eyepiece
• to adjust the focus until you get a clear image

Question 4

How would you view a slide with a greater magnification with a light microscope?

Answer 4

To view the slide with greater magnification, swap to a higher-powered objective lens and refocus.

Question 5

Where is the slide clipped?

Answer 5

onto the stage

Question 6

How should observations of a slide under a microscope be drawn?

Answer 6

1. Use a pencil with a sharp point
2. Ensure the drawing fills at least half of the space
3. Draw with clear, unbroken lines (not sketchy)
4. Don’t include colouring or shading
5. Draw sub-cellular structures of cells in proportion

Question 7

What should be written alongside a drawing of your observations of the slide under the microscope?

Answer 7

• title of what you observed
• magnification it was observed under
• label important features such as organelles using straight uncrossed lines

Question 8

How would you prepare a slide to view onion cells?

Answer 8

1. Add a drop of water to the slide.
2. Cut up an onion and separate it into layers. Use tweezers to peel off epidermal tissue.
3. Place epidermal tissue into water on slide using tweezers
4. Add a drop of iodine solution
5. Place a coverslip on top

Question 9

Why is iodine solution added to the slide of onion cells?

Answer 9

stains and highlights objects to make them clearer under microscope

Question 10

What should you be careful to avoid when placing the coverslip on top of the prepared slide and why?

Answer 10

• dont get any air bubbles
• they’ll obstruct the view

Question 11

What are the main differences between electron and light microscopes?

Answer 11

Electron:
+ can view specimens at a much higher magnification and at a higher resolution
- expensive, big and difficult to use

Light:
+ affordable, smaller, simple to use

• cannot view specimens at as high of a resolution or magnification

Question 12

What is the formula for magnification?

Answer 12

image size
magnification = ——————
actual size

(ensure sizes are in the same units)

Question 13

How would you calculate total magnification?

Answer 13

total magnification = magnification for eyepiece lens x magnification of objective lens