Microscopy

Question 1

What is microscopy?

Answer 1

The technical field of using microscopes to view objects and areas of objects that cannot be seen with the naked eye

Microscopy allows for the examination of very small specimens.

Question 2

Define magnification.

Answer 2

The number of times bigger the image is compared to the object

Magnification is a key concept in microscopy.

Question 3

What is resolving power or resolution?

Answer 3

The ability to distinguish separate objects

Higher resolution allows for clearer images of small structures.

Question 4

What are the two lenses used in light microscopes?

Answer 4

• Eyepiece
• Objective lens

These lenses work together to magnify the image of an object.

Question 5

Why do the samples used have to be very thin for light microscopes?

Answer 5

Specimens are usually backlit

Samples must be thin enough for light to pass through.

Question 6

What do electron microscopes use to achieve better resolution?

Answer 6

A beam of electrons

Electrons have a much smaller wavelength than visible light.

Question 7

List the advantages of light microscopes.

Answer 7

• Cheap and portable
• Simple preparation of samples
• Samples can be living or dead
• Easy to use
• Can see colours

Light microscopes are accessible for many applications.

Question 8

List the disadvantages of light microscopes.

Answer 8

• Low resolution (200 nm)
• Low magnification (×1000-2000)
• Specimens need to be thin enough for light to pass through

These limitations affect the detail that can be observed.

Question 9

What are the two types of electron microscopes?

Answer 9

• Transmission EM
• Scanning EM

Each type has different methods of imaging and magnification.

Question 10

What does a haemocytometer do?

Answer 10

Used to manually count cells

It is a gridded chamber that allows for accurate cell counting.

Question 11

What are Coulter counters?

Answer 11

Automatic cell counters that measure changes in electrical resistance

They provide accurate and reproducible results but are more expensive.

Question 12

What does iodine stain do?

Answer 12

Makes plant internal structures more visible

Stains enhance contrast in microscopy.

Question 13

What is the purpose of safranin stain?

Answer 13

Used to distinguish between gram-positive and gram-negative bacteria

This is important in microbiology for identifying bacterial types.

Question 14

What does methylene blue stain bind to?

Answer 14

Nucleic acids

This stain is used to identify nuclei in cells.

Question 15

What is an eyepiece graticule?

Answer 15

Fits the microscope eyepiece and contains a grid etched into a glass disc

It is used for measuring specimens under the microscope.

Question 16

What is a stage micrometer?

Answer 16

A calibrated slide with a scale divided into divisions

It is used for calibrating measurements in microscopy.

Question 17

How is total magnification calculated in a light microscope?

Answer 17

The product of the magnifications of the eyepiece and the objective lenses

This calculation is essential for understanding the level of detail observed.

Question 18

Fill in the blank: Sometimes a photograph includes a _______ for reference.

Answer 18

scale bar

This can be used to calculate the magnification of the image.