Phase Contrast Microscopy

Question 1

Phase contrast microscopy was first described in 1934 by Dutch physicist

Answer 1

Frits Zernike

Question 2

was first described in 1934 by Dutch physicist Frits Zernike

Answer 2

phase contrast microscopy

Question 3

a contrast-enhancing optical technique to produce high-contrast images of transparent
specimens

Answer 3

phase contrast microscope

Question 4

phase contrast microscope is used for transparent specimens such as

Answer 4

living cells (usually in culture)
microorganisms
thin tissue slices
subcellular particles (nuclei, other organelles)

Question 5

Phase-contrast microscopy converts ___shifts in the light passing through a transparent
specimen to brightness changes in the image, which is barely, or not at all, possible in a
brightfield microscope. T

Answer 5

phase shifts

Question 6

The phase shifts can be observed as differences in ____

Answer 6

image contrast

Question 7

why do phase shifts happen

Answer 7

undeviated and diffracted light collected by the objective is segregated at
the rear focal plane by a phase plate

Question 8

collects the undeviated and diffracted light by the objective

Answer 8

phase plate

Question 9

focuses the collected light from the phase plate and focused at the

Answer 9

intermediate image plane

Question 10

The phase shifts can be observed as differences in image contrast.
This happens when undeviated and diffracted light collected by the objective is segregated at
the rear focal plane by a phase plate and focused at the intermediate image plane to form the
final phase-contrast image observed in the ___.

Answer 10

eye pieces

Question 11

Phase-contrast microscopy is basically a specially designed light microscope
with all the basic parts, in addition to which are the

Answer 11

annular phase plate
annular diaphragm

Question 12

m is made up of a
circular disc having a circular annular groove and is situated below the
condenser

Answer 12

annular diaphragm

Question 13

is a transparent disc that is
either a negative phase plate having a thick circular area or a positive phase
plate having a thin circular groove.

Answer 13

phase plate

Question 14

how does phase contrast achieves its results with annular phase plate and annular diaphragm

Answer 14

This is by separating the direct rays from the
diffracted rays, the former passing through the annular groove, and the latter
through the region outside the groove

Question 15

phase contrast is achieved by separating the ___ rays from the ___ rays

Answer 15

direct rays
diffracted rays

Question 16

rays that passe sthrough the annular groove

Answer 16

direct rays

Question 17

rays that passes through the region outside the annular groove

Answer 17

diffracted rays

Question 18

has a corresponding match in lens

Answer 18

phase contrast

Question 19

view the illumination pathway

Answer 19

+1

Question 20

live microbial specimen include

Answer 20

yeast
e. coli
hay infusion
aspergillus niger

Question 21

. Place one to two loopfuls of ___ ___ and ___ on
separate glass slides. Put cover slip and set aside for microscopy.

Answer 21

bacterial
yeast suspension
hay infusion

Question 22

results in extremely small differences in the intensity distribution in the image.

Answer 22

poor light absorption

Question 23

is an optical microscopy technique that converts phase shifts in the light passing through a transparent specimen to brightness changes in the image.

Answer 23

phase contrast microscope

Question 24

When light passes through cells, small phase shifts occur, which are invisible to the human eye. In a phase-contrast microscope, these phase shifts are converted into changes in ___, which can be observed as differences in image contrast.

Answer 24

amplitude

Question 25

Partially coherent illumination produced by the ___ lamp is directed through a collector lens and focused on a specialized annulus (labeled condenser annulus) positioned in the substage condenser front focal plane.

Answer 25

tungsten halogen

Question 26

Partially coherent illumination produced by the tungsten-halogen lamp is directed through a collector lens and focused on a specialized ___(labeled condenser annulus) positioned in the substage condenser front focal plane.

Answer 26

annulus

Question 27

Wavefronts passing through the annulus illuminate the specimen and either pass through ___ or are ___and retarded in phase by structures and phase gradients present in the specimen.

Answer 27

undeviated diffracted

Question 28

Undeviated and diffracted light collected by the objective is segregated at the rear focal plane by a

Answer 28

phase plate

Question 29

Undeviated and diffracted light collected by the objective is segregated at the rear focal plane by a phase plate and focused at the

Answer 29

intermediate image plane

Question 30

It is situated below the condenser.

Answer 30

annular diaphragm

Question 31

It is made up of a circular disc having a circular annular groove.

Answer 31

annular diaphragm

Question 32

The light rays are allowed to pass through the annular groove.

Answer 32

annular diaphragm

Question 33

Through the ___groove of the annular diaphragm, the light rays fall on the specimen or object to be studied.

Answer 33

annular

Question 34

At the back focal plane of the objective develops an image.

Answer 34

annular diaphragm

Question 35

The annular phase plate is placed at

Answer 35

back focal plane of the objective

Question 36

It is either a negative phase plate having a thick circular area or a positive phase plate having a thin circular groove.

Answer 36

phase plate

Question 37

This thick or thin area in the phase plate is called the

Answer 37

conjugate area

Question 38

the phase plate is a ___disc.

Answer 38

transparent

Question 39

advantages of phase contrast microscopy

Answer 39

Living cells can be observed in their natural state without previous fixation or labeling. It makes a highly transparent object more visible. No special preparation of fixation or staining etc. is needed to study an object under a phase-contrast microscope which saves a lot of time. Examining intracellular components of living cells at relatively high resolution. eg: The dynamic motility of mitochondria, mitotic chromosomes & vacuoles. It made it possible for biologists to study living cells and how they proliferate through cell division. Phase-contrast optical components can be added to virtually any brightfield microscope, provided the specialized phase objectives conform to the tube length parameters, and the condenser will accept an annular phase ring of the correct size.

Question 40

limitations of phase contrast microscopy

Answer 40

Phase-contrast condensers and objective lenses add considerable cost to a microscope, and so phase contrast is often not used in teaching labs except perhaps in classes in the health professions. To use phase-contrast the light path must be aligned. Generally, more light is needed for phase contrast than for corresponding bright-field viewing, since the technique is based on the diminishment of the brightness of most objects.

Question 41

What are the main differences between phase contrast and bright-field microscope?

Answer 41

The main difference between phase contrast and bright-field microscopes lies in their method of enhancing contrast in transparent specimens. Phase contrast microscopy uses optical manipulation to translate subtle differences in refractive index and specimen thickness into variations in image intensity, making unstained structures visible e. In contrast, bright-field microscopy illuminates the sample with a direct beam of white light, often requiring staining to enhance contrast, which can obscure details and may be toxic to living cells. Phase contrast microscopy is better for observing live, transparent specimens, while bright-field suits stained samples, offering color representation.

Question 42

3. Why is phase contrast microscopy particularly useful for observing living cells?

Answer 42

Phase contrast microscopy is ideal for observing living cells because it doesn't require staining, which could possibly harm or alter cells. It converts differences in how light passes through different parts of the cell (refractive index) into variations in brightness, making transparent structures visible. This allows observation of cell processes real time (e.g. motility, movement, or chemotaxis) real time without disturbing the cells,

Question 43

4. Which cell structures are more clearly visible using phase contrast microscopy?

Answer 43

Phase contrast microscopy helps visualize cell structures that are transparent or low contrast under brightfield microscopy. This technique makes the nucleus, cell membrane, and organelles such as mitochondria, Golgi, and granules more apparent.

Question 44

view phase contrast results

Answer 44

+1

Question 45

6. What is the advantage of using phase contrast microscope in ecological studies?

Answer 45

Phase contrast microscopy (PCM) offers advantages in studying ecology because natural status of living microorganisms can be observed without staining. This feature is crucial in understanding the ecological niche and interaction within the environment, as aforementioned staining can possibly disturb the according study of behavior