Topic 1 - Microscopy

Question 1

What is the primary function of microscopes?

Answer 1

To enlarge the image of extremely small structures such as cells

Microscopes enable the observation of structures that cannot be seen with the naked eye.

Question 2

Who observed the first cells and in what year?

Answer 2

Robert Hooke in 1665

Hooke used a light microscope to observe cork cells.

Question 3

What are the main components of a light microscope?

Answer 3

Two lenses and illumination from underneath

The design allows for magnification and resolution of small structures.

Question 4

What is the maximum magnification of a light microscope?

Answer 4

Approximately 2000x

This allows for the viewing of tissues, cells, and large sub-cellular structures.

Question 5

Define resolving power in microscopy.

Answer 5

The ability to distinguish between two points

A lower resolving power indicates greater detail in the image.

Question 6

What is the resolving power of a light microscope?

Answer 6

200nm

This resolving power limits the detail that can be observed.

Question 7

What significant advancement in microscopy occurred in the 1930s?

Answer 7

The development of the electron microscope

This allowed scientists to view deeper inside sub-cellular structures.

Question 8

What is used to form an image in an electron microscope?

Answer 8

Electrons

Electrons have a much smaller wavelength than light waves, allowing for higher resolution.

Question 9

What are the two types of electron microscopes?

Answer 9

Scanning electron microscope (SEM) and transmission electron microscope (TEM)

SEM creates 3D images while TEM creates 2D images detailing organelles.

Question 10

What is the maximum magnification of a transmission electron microscope?

Answer 10

Up to 2,000,000x

This allows for viewing extremely small structures in detail.

Question 11

What is the resolving power of a transmission electron microscope?

Answer 11

0.2nm

This high resolving power enables the observation of very small cellular components.

Question 12

What types of structures can be viewed clearly with electron microscopes?

Answer 12

Organelles such as mitochondria, ribosomes, chloroplasts, and plasmids

Electron microscopes are crucial for studying small cellular structures.

Question 13

What important discoveries have been facilitated by transmission electron microscopes?

Answer 13

Discovery of viruses such as poliovirus, smallpox, and Ebola

This is especially important as viruses are much smaller than bacteria.

Question 14

True or False: Electron microscopes can examine proteins in greater detail than light microscopes.

Answer 14

True

This capability has led to many important scientific discoveries.

Question 15

What is the eyepiece in a microscope?

Answer 15

The part of microscope that we look through to view specimens.

Question 16

What is the function of the barrel in a microscope?

Answer 16

The upper part of the microscope that can be moved up or down to focus the image.

Question 17

What does the turret do in a microscope?

Answer 17

The part of the microscope that is rotated to change the magnification lens in use.

Question 18

What is the role of the lens in a microscope?

Answer 18

The lens increases the magnification of the specimen.

Question 19

What is the stage of a microscope?

Answer 19

The flat surface on which we place the specimen.

Question 20

List the steps to use a light microscope.

Answer 20

• Place the slide on the stage and look through the eyepiece lens
• Turn the focus wheel to obtain a clear image
• Start with the lowest objective lens magnification
• Increase the magnification of the objective lens and refocus.

Question 21

True or False: It is important to remember all steps when using a light microscope to gain full marks in a question about microscopy.

Answer 21

True

Question 22

What is the first step in preparing a slide for microscopy?

Answer 22

Take a thin layer of cells from your sample by either peeling them off or using a cotton bud.

Question 23

What is the purpose of chemical stains in microscopy?

Answer 23

Used to make some parts of the specimen more visible when you look at them through the microscope.

Question 24

What should you do after adding cells to the glass slide?

Answer 24

Carefully lower a coverslip onto your slide, taking care to avoid air bubbles.

Question 25

Fill in the blank: Magnification = measured size / _______

Answer 25

actual size

Question 26

How do you calculate actual size in microscopy?

Answer 26

Actual size = measured size / magnification.

Question 27

What is the formula for total magnification in microscopy?

Answer 27

Total magnification = objective lens magnification x eyepiece lens magnification.