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MICRIOBIOLOGY LAB > The compound microscope > Flashcards

The compound microscope Flashcards

1
Q

The smallest object that the eye can see at a distance of 250
mm is about

A

0.07-0.14mm

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2
Q

Two general categories of microscope

A
  1. Light Microscope
  2. Electron type microscope
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3
Q

Uses light waves and lenses that are associated with the light microscope

A

Light Microscope

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4
Q

employs electron beams and magnetic fields to produce the image.

A

Electron type microscope

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5
Q

Light microscope magnify objects only up to?

A

300X

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6
Q

employs two separate lenses, an ocular and an objective, in order to achieve 2-5 times greater
magnification.

A

Compound type microscope

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7
Q

where the microscope field is brightly lighted and the object to be observed appears dark die to its ability to absorb or refract some of the incident light

A

bright field

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8
Q

where the object appears luminous against a dark background since it reflects some of the incident light in all directions

A

dark-field

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9
Q

allowing greater resolution and magnification. It is used principally to detect or even measure substances in specimens of living tissues that are known to absorb UV light at particular wavelengths. UV is not visible to the eye, so the image formed is recorded with the use of cameras or a television screen.

A

Ultraviolet (UV)

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10
Q

UV is not visible to the eye, so the image formed is recorded with
the use of?

A

Cameras or television screen

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11
Q

which makes use of the property of certain chemical substances that
release light at a different wavelength when exposed to UV rays. Such substances convert UV light into visible waves of greater length.

A

Fluorescent

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12
Q

Bacteria and other microorganisms are stained with __________ that can be detected in a microscope illuminated with UV light.

A

fluorescent stain

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13
Q

utilizes the refraction that occurs when light passes from one medium into another of different density. The special objectives and condenser intensify slight differences in contrast produced by this bending of light.

A

phase-contrast

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14
Q

It is useful in studying the internal structures of microorganisms because structures differing in refractive index from the surrounding protoplasm become
visible, and their sizes and locations can be determined.

A

phase-contrast

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15
Q

keeps the microscope steady at any position of the stage

A

base

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16
Q

fastened to the base through the inclination joint, permits the adjustment of the stage to a desired angle

A

arm

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17
Q

reflects the light into the condenser

A

concave

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18
Q

concentrates the light rays received from the mirror and sends them to the objective

A

condenser

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19
Q

is a horizontal platform upon which the specimen to be examined is placed. At the center of the stage is a circular aperture

A

stage

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20
Q

hold the slide in place on the stage

A

stage clips

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21
Q

is that part of the optical system of the microscope which produces the specimen’s initial magnified image (real) within the body tube

A

objective

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22
Q

Three objectives of the microscope

A
  1. Low power
  2. High power
  3. Oil immersion
23
Q

The objectives are _______that is, they are corrected for the spectral colors of red and blue.

A

achromatic

24
Q

an optical constant of the lens system, is the distance from the center of the lens to the point where parallel rays entering the lens are brought to a focus.

A

Focal length

25
Q

that property to recognize features of a specimen that are close to each other as separate or distinct.

A

Resolving power

26
Q

The greater the resolving power,?

A

The greater the definition of an objective

27
Q

This property is dependent on the wavelength of light used and an optical property of the objective lens known as a numerical aperture.

A

Resolving power

28
Q

is a measure of the resolving power of an objective. An objective with a 0.25 N.A. allows the viewer to distinguish as separate 25,000 lines per inch.

A

Numerical aperture (N.A)

29
Q

Lenses with higher magnification usually have higher N.A. but the medium through which the
light passes also affects N.A.
T/F

A

True

30
Q

means that the objectives are optically ad mechanically designed so that the distance between the specimen and the aerial image is always constant.

A

Parfocal

31
Q

___________________________ is sufficient to restore critical sharpness of the image after changing from one objective to another, thus, the coarse focus knob need not to be operated.

A

Slight refocusing with the aide of the fine focus knob

32
Q

to which parfocal objectives are attached, allows convenient
shifting of the objectives

A

revolving nosepiece

33
Q

is a hollow cylindrical tube through which light passes from the objective to the eyepiece

A

body tube

34
Q

The upper portion of the body tube is called the ______________

A

draw tube

35
Q

that part of the optical system through which the specimen is viewed.

A

eyepiece or ocular

36
Q

The intermediate image projected by the objective is enlarged by the______________

A

eyepiece

37
Q

The term compound microscope is derived from?

A

from the fact that the specimen is magnified twice, first by the objective and second by the eyepiece

38
Q

The final image formed is called?

A

virtual image

39
Q

The magnification of the compound microscope is, therefore, the product of the

A

magnifying power of the objective and the eyepiece.

40
Q

If the magnifying power of the objective is 100X and the eyepiece is 10X, the total magnification will be

A

1000X

41
Q

The _____________________ knob is used to bring the objective into approximate focus. For maximum
definition, the ____________________ knob is used.

A

Coarse focus; fine focus knob

42
Q

What comprise the optical system?

A

The mirror, the condenser, the objective and the eyepiece

43
Q

The __________________________ has a much greater depth of focus and is
generally used for initial focusing and viewing.

A

low power objective

44
Q

the higher the magnification of the objective, the larger the working distance. T/F

A

False; smaller working distance

45
Q

The free space between the specimen surface and the objective is the?

A

working distance (mm)

46
Q

The higher the power of the
objective, the lesser is the area of the specimen surface included in the field of vision. T/F

A

True

47
Q

If a sharp image is not obtained despite the application of the above procedure, it is possible that:

A

 The fine focus knob has reached a stop. On the right side of the microscope at the
rack and pinion area are three lines. Center the line (located on the fine focus knob side) between the two lines (located below the coarse focus knob) by turning the fine focus knob.

 Focusing attempts are too rapid. Use the fine focus knob and adjust slowly.

 The objective is covered with dried oil from previous use. Under the supervision of your instructor, remove the dried oil with xylene or 95% ethanol and dry the
lens right away.

 The cover slip is too thick. The optimum thickness is 0.17 mm.

 The slide is inverted.

48
Q

After using the oil immersion objective:

A

 Blot out the oil with lens paper

 Clean the lens with lens paper wet with xylol (do this under the instructor’s supervision)

 Blot-dry the lens with fresh lens paper

49
Q

Microscopic objects can be measured by means of an ocular micrometer or a ___________

A

Filar micrometer

50
Q

The unit of linear measurement in microbiology is the micrometer (µm), which is equivalent to _________________

A

1/1000 mm or 1/25,400 inch

51
Q

is a glass disc with mounted scale. It may or may not have numbers on it. It is inserted into the eyepiece and must be calibrated for the particular objective, eyepiece and tube length before measurements are made. The
student microscope has a fixed tube length.

A

ocular micrometer

52
Q

is a glass slide with graduations of known intervals

A

stage micrometer

53
Q

Some micrometers have numbers to indicate the _________________

A

length of the divisions

54
Q

Which is a bigger division, 0.01 mm or 0.1mm

A

0.1mm

MICRIOBIOLOGY LAB (3 decks)

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