PAGs Key Points

Question 1

Rules for making biological drawing?

Answer 1

• Include a title
• State magnification
• Include a scale
• Draw smooth, continuous lines
• No shading
• Horizontal label lines that DON’T cross and have NO arrow head
• Extra details observed in the labels e.g. colours

Question 2

Why is cover slip on microscope slide added at an angle?

Answer 2

To prevent bubbles forming which would create artefacts

Question 3

Why are solid specimens cut into thin slices (sectioned) when preparing a dry mount slide?

Answer 3

So light can pass through it and individual cells can be observed

Question 4

How is wet mount slide prepared?

Answer 4

Suspend specimen in liquid (only a few drops) and place cover slip over

Question 5

How are squash slides prepared?

Answer 5

Prepare wet mount then press cover slip gently over it

Question 6

How are smear slides prepared?

Answer 6

Edge of slide used to smear sample on another slide

Question 7

What is the purpose of staining?

Answer 7

Increases contrast between different components of cell to make them easier to see. This is called differential staining.

Question 8

How may divisions on a stage micrometer (1000μm)?

Answer 8

100 divisions each 10μm wide

Question 9

What is an artefact?

Answer 9

Structural detail which is not actually a part of the specimen but often a result of air bubbles

Question 10

What should be done with excess stain on a slide?

Answer 10

Blotted away with a tissue

Question 11

Explain how to calibrate the eye piece graticule?

Answer 11

Use a stage micrometer to identify the width of each division on the EPG. Then use the calibrated units of EPG to measure actual size of organelle/cell

Question 12

What are the benefits of staining?

Answer 12

• Allow for greater contrast
• Allows differences between organelles to be seen
• Allows differences between cells to be seen
• Allows for a clearer image to be obtained
• Allows internal structures to be more visible because they bind to stain