microscopes

Question 1

define magnification

Answer 1

How many times bigger the image is when compared to the real size of the object

Question 2

define resolution

Answer 2

The ability to distinguish between two separate points

Question 3

describe the light (optical) microscope

Answer 3

Uses light to form an image. They have a max resolution of 0.2um so they can’t be used to see organelles such as ribosomes, ER or lysosomes. The maximum resolution is around x1500. Produces coloured images

Question 4

describe the scanning electron microscope

Answer 4

They scan a beam of electrons across the specimen. This knock’s off electrons from the specimen, which are gathered in a cathode ray tube to form an image. 3D images are possible and has a max resolution of around 0.2nm. The max magnification is around x1500000. The images produced are black and white but they’re artificially coloured. It requires a vacuum

Question 5

describe the transmission election microscope

Answer 5

Electromagnets are used to focus a beam of electrons. Denser parts absorb more electrons so look darker. It has a maximum resolution of around 0.1nm and a maximum magnification of around x1500000. The images produced are black and white but can be artificially coloured.

Question 6

What is an advantages of using an SEM microscope instead of a TEM?

Answer 6

It can be used on thicker specimens and can produce 3D images

Question 7

What is a disadvantage of using a SEM microscope instead of a TEM microscope?

Answer 7

It gives a lower resolution than a TEM and can only be used on non living specimens

Question 8

What is an advantage of using a TEM microscope instead of a SEM microscope?

Answer 8

Gives a higher resolution image and shows small objects

Question 9

What is a disadvantage of using a TEM microscope instead of a SEM microscope?

Answer 9

Can only be used on thin specimens and non living specimens

Question 10

How do you prepare a microscope slide?

Answer 10

1. Squeeze a small drop of water onto the centre of the slide using a pipette
2. Use tweezers to place a thin section of specimen on top of the water drop
3. Add a stain to highlight objects in the cell
4. Add a cover slip by standing the slip upright on the slide next to the water droplet then carefully tilt it and lower it so it covers the specimen. This lowers the chance of air bubbles

Question 11

Why does the specimen have to be thin when preparing a microscope slide?

Answer 11

So that light can pass though to be able to produce a clear image

Question 12

How do you convert from micrometers (um) to nanometres (nm)

Answer 12

X by 1000

Question 13

How do you convert from nanometres (nm) to micrometers (um)?

Answer 13

Divide by 1000