B1 - Microscopy

Question 1

What is used to study cells?

Answer 1

Microscopes

Question 2

How do light microscopes work and what do they let us do?

Answer 2

They use light and lenses to form an image of a specimen and magnify it.
They let us see individual cells and large sub cellular structures.

Question 3

How do electron microscopes work and what do they let us do?

Answer 3

They use electrons instead of light to form an image. They have a much higher magnification than light microscopes, they also have a higher resolution.

They let us see much smaller things in more detail, like the internal structure of mitochondria and chloroplasts. They even let us see tiny things, such as ribosomes and plasmids.

Question 4

What do these words mean?

• Magnify
• Resolution

Answer 4

• make something look bigger.

- the ability to distinguish between two points, so a higher resolution gives a sharper image.

Question 5

What is the formula for magnification?

Answer 5

Magnification = image size divided by real size

Question 6

How do you convert micrometres (um) to millimetres (mm)?

Answer 6

Divide um by 1000 to get mm.

E.g - 5000um = 5mm

Question 7

How do you prepare a slide to view onion cells?

Answer 7

• Add a drop of water to the middle of a clean slide.
• Cut an onion up and separate it out into layers.
• Use tweezers to peel off some epidermal tissue from the bottom of one of the layers.
  -Place this tissue into the water on the slide.
• Add a drop of iodine solution - this is a stain.
  Stains are used to highlight objects in a cell by adding colour to them.
• Place a cover slip (square transparent, thin glass) 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 covers the specimen. Try not to get any air bubbles under there - they’ll obstruct your view of the specimen.

Question 8

How do you use a Light Microscope?

Answer 8

A

Question 9

How do you draw your observations?

Answer 9

A