Bio Unit 1.2 (Microscopy)

Question 1

Organelles seen by light microscope

Answer 1

Nucleus, Cell Wall, Vacuole

Question 2

Why is it called compound microscope?

Answer 2

Has got more than one lens

Question 3

Largest to Smallest Objects

Answer 3

Plant cell, animal cell, most bacteria, chloroplasts, ribosome, proteins, lipids, atoms

Question 4

Milimetre to micrometre

Answer 4

x1000

Question 5

Micrometre to nanometre

Answer 5

x1000

Question 6

Cm to mm

Answer 6

x10

Question 7

AIM triangle - how do you find I?

Answer 7

measure the image

Question 8

How to calculate magnification using scale bar?

Answer 8

Measure scale bar, convert to micrometers, measure image length, convert to micrometers, use M=I/A to find magnification

Question 9

Calibration is necessary

Answer 9

to measure size of structure on microscope slide

Question 10

Eye piece graticule has

Answer 10

10 subdivisons (100 epu) along its length

Question 11

Stage micrometer (1mm long)

Answer 11

measures length of each division at different magnifications

Question 12

100 smu is equal to

Answer 12

1mm

Question 13

1 smu is equal to

Answer 13

0.01mm/10 micrometres

Question 14

Calibration Instruction

Answer 14

Line up zeros of eyepiece and micrometer, make sure scales are parallel, see where scales line up

Question 15

Resolution limited by …

Answer 15

Wavelength of light (objects closer together than half wavelength of light e.g 200nm cannot be seen by light microscope.)

Question 16

Magnification

Answer 16

How much bigger a sample appears under a microscope compared to actual size

Question 17

How do you find length of objects after finding 1 epu?

Answer 17

Epu length x 1 epu (micrometre)

Question 18

Resolution

Answer 18

How close two points can be and still be separately distinguished rather than being seen as a single image

Question 19

Why will objects blur at 200nm

Answer 19

diffraction limit of light (higher magnification will increase size of image, not resolution.)

Question 20

TEM (transmission electron microscope)

Answer 20

thin slices/sections of cells (view organelles too small for light microscope)

Question 20

SEM (scanning electron microscope)

Answer 20

large field view of whole cell (poorer revolution but give good 3D images)

Question 21

Why do cells have to be non-living?

Answer 21

Electrons will be deflected by air particles

Question 22

Maximum resolution for all 3

Answer 22

Light - 200nm
TEM - 0.1nm
SEM - 1nm

Question 23

Staining for all 3?

Answer 23

Light - yes (methylene blue)
TEM - heavy metals
SEM - heavy metals (e.g gold)

Question 23

Is a vacuum required for electron microscopy?

Answer 23

Yes

Question 23

Sectional or External?

Answer 23

Light - external (except for tissues)
TEM - section
SEM - external