Microscope

Question 1

What are the rules for biological drawing?

Answer 1

Observe the specimen and record what you see clearly and accurately. Labelled drawings and diagrams can be used.

Question 2

What are some points you need to remember when observing through a microscope?

Answer 2

• Draw what you see, not what you think you should be seeing.
• Always use a sharp pencil
• Make your drawings large
• Make the lines clear and sharp
• Do not shade or colour in any areas
• Make sure the different parts of the drawing are in proportion
• Labels should be spaced neatly around the drawing

Question 3

What is the difference between electron and light microscopes?

Answer 3

Electron microscopes have a higher resolution and magnification than light microscopes.

Question 4

What is magnification?

Answer 4

Magnification is how much bigger a sample appears to be under the microscope than it is in real life.

Question 5

What is resolution?

Answer 5

Resolution is the ability to distinguish between two points on an image i.e. the amount of detail

Question 6

Pros and cons of electron microscopes

Answer 6

• Expensive to buy
• Expensive to produce electron beam.
• Large and requires special rooms.
• Lengthy and complex sample prep.
• Preparation distorts material.
• Vacuum is required.
• All images in black and white.
• Magnifies over 500 000 times.
• Specimens are dead, as they must be fixed in plastic and viewed in a vacuum
• The electron beam can damage specimens and they must be stained with an electron-dense chemical (usually heavy metals like osmium, lead or gold).

Question 7

Pros and cons of light microscopes

Answer 7

• Cheap to purchase
• Cheap to operate.
• Small and portable.
• Simple and easy sample preparation.
• Material rarely distorted by preparation.
• Vacuum is not required.
• Natural colour of sample maintained.
• Magnifies objects only up to 2000 times
• Specimens can be living or dead
• Stains are often needed to make the cells visible

Question 8

What are the main limitations of the electron microscope?

Answer 8

The inability to observe living specimens, difficulty of preparation of samples and expensive equipment are the main limitations.

Question 9

What are the main limitations of the light microscope?

Answer 9

Low resolution and as a result cannot magnify above x1500 and still give a clear image

Question 10

What is cell division? (mitosis)

Answer 10

The division of a cell into two daughter cells with the same genetic material.

Question 11

Magnification

Answer 11

x 1000 x1000
mm μm nm

Example: 1mm 1000μm 1,000,000nm

Question 12

Equations

Answer 12

Actual size = Image size ➗ Magnification

Magnification= Image size ➗ Actual size