2.1. 1-3 Microscopes

Question 1

What is an electron micrograph?

Answer 1

photograph of an image seen using an electron microscope

Question 2

Define magnification

Answer 2

the number of times large an image appears, compared with the size of the object.

Question 3

Define organelles

Answer 3

small structures within cells, each of which has a specific function

Question 4

What is a photomicrograph

Answer 4

photograph of an image seen using an optical microscope

Question 5

Define resolution

Answer 5

the clarity of an image; the higher the resolution the clearer the image

Question 6

What is an optical microscope

Answer 6

A microscope that uses Light as its Radiation source and produces 2D images in colour.

Question 7

Maximum Resolution of an optical microscope

Answer 7

0.2nm

Question 8

Maximum magnification of an optical microscope

Answer 8

x1500-2000

Question 9

Advantages of using an Optical microscope

Answer 9

1. Easy to use
2. Can observe live specimens
3. Colour images
4. Portable
5. Cheap

Question 10

Disadvantage of optical microscope

Answer 10

1. 2D images

2. Very small organelles such as Ribosomes cannot be seen

Question 11

What is a Transition Electron Microscope [TEM]

Answer 11

Transition Electron Microscopes use Electrons as it’s radiation source and they produce images 2D image in greyscale

Question 12

Maximum Resolution of a Transition Electron Microscope

Answer 12

0.2um

Question 13

Maximum Magnification of a Transition Electron Microscope

Answer 13

x500,000

Question 14

Advantages of a Tranmission Electron Microscope

Answer 14

1. High Magnification

Question 15

Disadvantage of a Tranmission Electron Microscope

Answer 15

1. Greyscale Images
2. Expensive to use
3. Requires Training to use
4. 2D greyscale images
5. Live Specimen cannot be used

Question 16

What is a Scanning Electron Microscope?

Answer 16

Scanning Electron Microscopes use Electrons as it’s radiation source and they produce 3D images in colour

Question 17

Maximum Resolution of a Scanning Electron Microscope

Answer 17

0.2um

Question 18

Maximum Magnification of a Scanning Electron Microscope

Answer 18

x100,000

Question 19

Advantage of Scanning Electron Microscope

Answer 19

1. 3D Colour Images

Question 20

Disadvantages of Scanning Electron Microscope

Answer 20

1. Live specimen cannot be used
2. Expensive
3. Requires special training

Question 21

What are confocal laser scanning microscopes

Answer 21

They are used to obtain high image resolution at a particular depth.

Question 22

What is light interference

Answer 22

Some microscopes use light interference, rather than light absorption to produce a clear image without staining

Question 23

What are stains

Answer 23

Stains are colored chemicals that bind to molecules in or on the specimen making it easier to see

Question 24

What is differential staining

Answer 24

Some stains bind to specific structures e.g Iodine in potassium iodide solution stains cellulose in plant cell walls yellow and starch granules blue/black

Question 25

What is the magnification formula

Answer 25

I= AxM

Question 26

What is an eye piece graticule

Answer 26

a measuring device. It is placed in the eyepiece of a microscope and acts as a ruler when you view an object under the microscope.

Question 27

What is a stage graticule

Answer 27

a precise measuring device. It is a small scale placed on the microscope stage used to calibrate the value of eyepiece divisions at different magnifications