Microscopy

Question 1

Definition of resolution

Answer 1

Ability to distinguish between two points and how much detail can be seen

Question 2

Definition of magnification

Answer 2

The degree to which the size of an image is larger than itself

Question 3

Maximum magnification and resolution of a light microscope

Answer 3

Resolution is 200nm
Magnification is 1500X

Question 4

Maximum magnification and resolution of a TEM microscope

Answer 4

Resolution is 0.1nm
Magnification is 500,000X

Question 5

Maximum magnification and resolution of a SEM microscope

Answer 5

Resolution is 0.1nm
Magnification is 100,000X

Question 6

Maximum resolution of a human eye and why

Answer 6

Resolution is 100μm because electrons have a much shorter wavelength than light

Question 7

Label the parts of a light microscope from top to bottom

Answer 7

1. Eyepiece-Contains eyepiece graticule
2. Body tube
3. Coarse adjustment screw
4. Fine adjustment screw
5. High power and low power objective lenses
6. Arm
7. Stage
8. Condenser
9. Mirror
10. Lamp
11. Base

Question 8

What is the equation for magnification, SA of a sphere and volume of a sphere

Answer 8

Magnification= Image size/Actual size
I
M A

SA of sphere= 4πr^2

Volume of sphere= (4/3) × π × r³

Question 9

What are the steps to calibrate an eyepiece graticule

Answer 9

1. Align the graticule with the stage micrometre
   2.Count the number of divisions on the micrometre that the graticule takes up
2. Note the actual value of one division on the micrometre
3. Multiply the actual value by the number of divisions the graticule took up. This is the actual length of the graticule
4. Divide this by 100 (number of divisions on the graticule) to calculate the actual value of one graticule division
5. Measure the size of a specimen using the graticule
   NOTE: Graticule must be recalibrated for each objective power

Question 10

How to convert all units (Write this down on exam paper)

Answer 10

cm
÷10⬆️ ⬇️X10
mm
÷1000⬆️ ⬇️X1000
μm
÷1000⬆️ ⬇️X1000
nm

Question 11

Define sectioning

Answer 11

Thin sections of a specimen are cut so light can easily pass through it which allows us to easily identify parts of the specimen

Question 12

Define staining

Answer 12

To apply a stain to a specimen which binds to chemicals or structures which colours them in and allows them to be seen. Some stains will specifically bind to certain structures which allows them to be differentiated from others, known as differential staining

Question 13

The image of a mitochondria is 12cm long with a magnification of 20000X.
Calculate its actual length (3 marks)