Cell structure

Question 1

types of microscopes

Answer 1

• optical (light)
• transmission electron (TEM)
• scanning electron (SEM)

Question 2

features of light microscope

Answer 2

• uses light to form an image
• wavelength is between 500 - 600nm
• max resolution of 200nm / 0.2µm
• max magnification of x1500
• observes eukaryotic cells
• in colour and 3D imaging

Question 3

light microscope
(advantages)

Answer 3

• relatively affordable
• live samples can be used

Question 4

light microscope
(disadvantages)

Answer 4

• poor resolution at high magnification
• relatively poor resolution of 0.2µm

Question 5

features of transmission electron (TEM)

Answer 5

• uses electromagnets to focus a beam of electrons
• denser parts of specimen absorb more electrons
• max magnification x1,000,000
• max resolution 0.17nm (spatial)

Question 6

transmission electron (TEM)
(advantages)

Answer 6

• high resolution images
• allows the internal structures within cells to be seen
• black and white and 2D imaging

Question 7

transmission electron (TEM)
(disadvantages)

Answer 7

• cannot observe live specimens
• only used on very thin specimens
• does not produce a colour image

Question 8

features of scanning electron (SEM)

Answer 8

• scans a beam of electrons across the specimen
• beam bounces off the surface of the specimen
• max maginification roughly x1,000,000
• max resolution 20nm

Question 9

scanning electron (SEM)
(advantages)

Answer 9

• allows the external 3D structure of specimens to be observed
• large depth of field
• high magnification x100,000

Question 10

scanning electron (SEM)
(disadvantages)

Answer 10

• gives lower resolution images
• cannot observe live specimens

Question 11

magnification formula

Answer 11

• magnification = size of image / size of real object

Question 12

magnification

Answer 12

• how much bigger an image appears compared to the original object

Question 13

resolution

Answer 13

• the abliity to distinguish two different components in a specimen