Required Practical 1: Calculation of magnification of drawings, actual size of structures from drawings or micrographs.

Question 1

Independent and dependent variables

Answer 1

No independent variable

No dependent variable

Question 2

Equation to calculate magnification

Answer 2

Magnification = Image size (with ruler) ÷ Actual size (according to scale bar)

Question 3

Equation to calculate actual size of a specimen

Answer 3

Actual Size = Image size (with ruler) ÷ Magnification

Question 4

What can light microscopes be used for and what is an advantage of using a light microscope?

Answer 4

• Light microscopes use visible light and a combination of lenses to magnify images of mounted specimens.
• Living specimens can be viewed in their natural colour, although stains may be applied to resolve specific structures.

Question 5

What conventions should be followed when attempting to draw microscopic structures?

Answer 5

• A title should be included to identify the specimen (e.g. name of organism, tissue or cell)
• A magnification or scale should be included to indicate relative size
• Identifiable structures should be clearly labelled (drawings should only reflect what is seen, not idealised versions)

Question 6

More info neede?

Question 7

Labelled diagram of light microscope

Answer 7

Question 8

Outline the procedure for focusing a light microscope

Answer 8

• Place the object on the stage «centered» below the objective lens/above the light
• Focus by moving the objective lens and specimen apart rather than towards each other
• Use coarse/large focusing first/to find areas of interest and then fine/small focusing «knob»
• Use low power first/to find areas of interest
• Use high power to look in detail
• Adjust light intensity