Microscopy

Question 1

Describe the main function of a light
microscope.

Answer 1

A light microscope uses light and different
lenses to magnify objects, allowing the image
to be seen through an eyepiece.

Question 2

Define magnification in the context of
microscopy.

Answer 2

Magnification is the number of times greater
the image is than the specimen.

Question 3

Explain the concept of resolution in
microscopy.

Answer 3

Resolution is the ability to distinguish
between two points on an image; higher
resolution results in a sharper image.

Question 4

How does one calculate the magnification of
a sample viewed using a microscope?

Answer 4

Magnification can be calculated by dividing
the size of the image by the actual size of the
specimen.

Question 5

List the working parts of a light microscope.

Answer 5

The working parts include the base, arm,
stage, light source, condenser, objective lens,
eyepiece, course focus, and fine focus.

Question 6

Compare scanning and transmission electron
microscopes.

Answer 6

Scanning electron microscopes provide 3D
images of surfaces, while transmission
electron microscopes allow for viewing
internal structures at a higher resolution

Question 7

Identify the best possible magnification
achievable with a light microscope.

Answer 7

The best possible magnification with good
resolution using a light microscope is x1000

Question 8

How do staining techniques enhance
microscopy?

Answer 8

Staining techniques enhance microscopy by
increasing contrast in the sample, making it
easier to identify different structures within
cells

Question 9

Summarize the general method for making a
wet mount slide.

Answer 9

To make a wet mount slide, place a drop of
liquid on a slide, gently lower a coverslip at
an angle to avoid air bubbles, and ensure the
specimen is flat.

Question 10

Recall the units of length commonly used in
microscopy

Answer 10

Common units of length in microscopy include
micrometers (µm) and nanometers (nm).

Question 11

Describe the process of making a wet mount
microscope slide.

Answer 11

To make a wet mount slide, add a drop of the
specimen in solution onto the slide, then add
a drop of stain, and cover it with a cover slip.

Question 12

Define the purpose of using methylene blue
in microscopy.

Answer 12

Methylene blue is a stain used to enhance
visibility of cells under magnification by
providing contrast.

Question 13

How does an electron microscope differ from
a light microscope?

Answer 13

An electron microscope uses electrons
instead of light to produce detailed images
with much higher magnification and
resolution.

Question 14

What are the two types of electron
microscopes?

Answer 14

The two types of electron microscopes are
Transmission Electron Microscopes (TEM) and
Scanning Electron Microscopes (SEM).

Question 15

Explain the significance of magnification in
microscopy.

Answer 15

Magnification allows for the enlargement of
images of specimens, making it possible to
observe details that are not visible to the
naked eye.

Question 16

How is magnification calculated in
microscopy?

Answer 16

Magnification is calculated using the formula:
Magnification = image size / actual size.

Question 17

Describe the characteristics of a Transmission
Electron Microscope (TEM).

Answer 17

A Transmission Electron Microscope (TEM)
transmits electrons through a specimen to
produce detailed images, allowing for high
resolution viewing of internal structures.

Question 18

What is a micrograph?

Answer 18

A micrograph is a photograph of a specimen
taken through a microscope.

Question 19

How can you prepare samples for viewing in
electron microscopy?

Answer 19

Samples for electron microscopy must be
specially prepared, often involving fixation,
dehydration, and embedding in resin.

Question 20

Discuss the importance of resolution in
microscopy.

Answer 20

Resolution is crucial in microscopy as it
determines the ability to distinguish between
two closely spaced objects, impacting the
clarity of the image.

Question 21

What is the typical magnification range for
electron microscopes?

Answer 21

Electron microscopes typically have a
magnification range from X200,000 to
X2,000,000.

Question 22

Explain the role of a cover slip in preparing a
microscope slide.

Answer 22

A cover slip protects the specimen, prevents
contamination, and helps to flatten the
specimen for better viewing under the
microscope.

Question 23

How can practicing units of length be
beneficial in microscopy?

Answer 23

Practicing units of length helps in accurately
measuring and converting sizes of specimens
and understanding their scale in microscopy.

Question 24

What is the difference between scanning and
transmission electron microscopes?

Answer 24

Scanning Electron Microscopes (SEM) provide
3D images of the surface of specimens, while
Transmission Electron Microscopes (TEM)
provide detailed images of internal structures.

Question 25

Describe the steps to calculate magnification.

Answer 25

1. Measure the length of the scale bar in millimeters. 2. Convert this measurement to scale units (micrometers), remembering that 1 mm equals 1000 μm. 3. Divide the image length by the scale length.

Question 26

Define the purpose of staining in microscopy.

Answer 26

Staining is necessary because cells can appear transparent and not visible, making it especially difficult to see organelles.

Question 27

How does iodine staining work?

Answer 27

Iodine is a simple technique using a diluted iodine solution that helps to give contrast to cell structures and will bind to starch, turning it blue-black in plant cells.

Question 28

Explain the function of eosin and haematoxylin in tissue examination.

Answer 28

Eosin and haematoxylin are contrast stains used in tissue examination; haematoxylin turns the nuclei blue, while eosin turns the cytoplasm and other parts pink.

Question 29

What is the role of methylene blue in staining?

Answer 29

Methylene blue is a simple stain used for animal cells and blood smears to make nuclei, DNA, and RNA more visible, with dead cells taking up the stain more easily than living cells.

Question 30

Describe the process of Gram staining

Answer 30

Gram staining uses two different counterstains, crystal violet and safranin, to distinguish between Gram positive and negative bacteria. Positive cells have a thick peptidoglycan layer that traps the crystal violet, staining them purple, while negative cells have a thin layer and stain pink.

Question 31

How do Gram positive and Gram negative bacteria differ in staining results?

Answer 31

Gram positive bacteria stain purple due to a thick peptidoglycan layer that retains crystal violet, while Gram negative bacteria stain pink due to a thin outer layer that does not retain the crystal violet.