Microscopy, Size & Magnification

Question 1

Parts of a Light Microscope

5 marks

Answer 1

• Eyepiece
• Objective Lens
• Stage
• Focusing Knob
• Light Source

Question 2

Differences between Light Microscope and Electron Microscope: Light Microscope

(3 marks)

Answer 2

Light Microscope - shows details 0.2µm apart.

Needs a Magnification of x1500 so our eyes can see it.

Allows us to see larger cell structures.

Question 3

Electron Microscopes

1 mark

Answer 3

Passes beams of electrons through a specimen

Question 4

Differences between Light Microscope and Electron Microscope: Electron Microscope

(3 marks)

Answer 4

Electron Microscope - Greater resolution

Shows details 0.0001µm apart

Allows us to look inside the parts of a cell (inside chloroplasts/mitochondria)

Question 5

How to look at Plant Cells through a microscope

4 marks

Answer 5

1. Peel thin, transparent layer of epidermal cells from inside of an onion
2. Place cells on (microscope) slide
3. Add a drop of water/iodine
4. Lower coverslip onto the cells using forceps or a mounted needle - gently to prevent trapping air bubbles

Question 6

How to look at Animal Cells through a microscope

4 marks

Answer 6

1. Remove cells from inside your cheek using a cotton bud
2. Smear cotton bud onto a slide
3. Add a drop of methylene blue (a Chemical Strain)
4. Lower coverslip onto the cells using forceps or a mounted needle - gently to prevent trapping air bubbles

Question 8

Lens can become damaged as it’s close to the slide

1 mark

Answer 8

High powered lens

Question 9

Chemical Strains

1 mark

Answer 9

Used to make some cell parts more obvious.

Question 10

Lower power objective lens

3 marks

Answer 10

• In a Compound Microscope

- Lens closest to specimen = short focal length and produces magnified image of specimen.

Question 11

Objective Lens

3 marks

Answer 11

In a compound microscope - lens closest to the specimen

• has a short focal length and produces a magnified image of the specimen.

Question 11

Field of View

1 mark

Answer 11

Area seen when looking through a microscope

Question 12

Slide

2 marks

Answer 12

Thin piece of glass used to hold objects which are examined under a microscope

Question 13

Resolution

1 mark

Answer 13

Ability to show detail.

Question 15

Actual Length =

2 marks

Answer 15

Length of Image
_________________________________

       Magnification

Question 16

Magnification
(Equation)

(2 marks)

Answer 16

Size of Image
_____________________________________

Actual Size of Object

Question 17

Magnification calculation

3 marks

Answer 17

• Measure scale bar image in mm
• Convert to µm (x1000)
• Magnification = scale bar image divided by actual scale bar length (written on the scale bar)

Question 18

Total Magnification =

2 marks

Answer 18

Eyepiece Magnification
x
Objective Lens Magnification

Question 19

Scale Bar

3 marks

Answer 19

• Line drawn near an image/drawing, labelled showing the actual length of the bar before magnified
• Magnification can be calculated using a scale bar

Question 20

mm

1 mark

Answer 20

Millimetre

Question 21

µm

1 mark

Answer 21

Micrometre

Question 22

Convert mm to µm

(Convert Millimetres to Micrometres)

(1 mark)

Answer 22

x100

Multiply by 100

Question 23

Once cells are in the middle of the field of view - you should?

(2 marks)

Answer 23

Rotate a higher powered lens into place

and begin to view the cells in more detail

Question 24

Drawing Cell Structures

4 marks

Answer 24

Drawn in pencil - lines firm, continuous, no gaps

Large - Same proportions as the observed cell

Labelled - using separate ruled lines, spread out, bullet point one end and written label on the other

Title - includes its magnification or size

Question 24

m

1 mark

Answer 24

Metre

Question 25

Coverslip

2 marks

Answer 25

Small, square of glass placed on top of a specimen to prevent the cells drying out

• and to protect the microscope lens should it have contact with the slide.

Question 26

Resolution: Detailed

3 marks

Answer 26

Fineness of detail that can be seen in an image -

Higher the resolution of an image = more detail it holds.

In computing terms, resolution is measured in dots per inch (dpi).

Question 27

Epidermal

2 marks

Answer 27

Protective outer layer of skin

• in this investigation it is a single layer of cells found inside an onion.