LAB EXAM 1 EXERCISES

Question 1

Ocular or eyepiece function?

Answer 1

Magnifies the image formed by the objective lens

Question 2

Objectives microscope part function?

Answer 2

Primary magnifying lens,

Has a 4x, 10x, 40x, and 100x

Question 3

It holds the ocular and objective at proper distance;
It may also transmit light to the eyepiece as well

Answer 3

Body Tube

Question 4

Holds and allows rotation of objective lenses to change magnification

Answer 4

Revolving nosepiece

Question 5

It gathers and focuses light on to the specimen

♤ It takes the light from the illuminator and concentrates it into a narrow, bright cone to shine uniformly onto the specimen.

Answer 5

Condenser

Question 6

It regulates the amount of light entering the condenser for contrast and resolution

Answer 6

Iris-diagphragm

Question 7

Stage function?

Answer 7

It is a flat platform where the slide is placed

Question 8

Stage clip function?

Answer 8

It secures the glass slide in position

Question 9

This microscope part allows smooth and precise movement of the slide horizontally or vertically with control knobs

Or,

▪︎ ​A device that holds a specimen slide and allows for precise movement in two dimensions (X and Y axes).

▪︎ ​A component of a microscope that provides precise control and movement of the specimen being observed, enabling the user to systematically scan the entire sample.

Answer 9

Mechanical stage

Question 10

Mirror function in microscope?

Answer 10

♡ It directs light through the condenser for compound microscope

♡​ It gathers and reflects external light up through the condenser and diaphragm to illuminate the specimen.

Question 11

Permits tilting of microscope for comfy viewing

Answer 11

Inclination joint

Question 12

It adjusts and centers the condenser beneath the stage

Answer 12

Substage screw

Question 13

Base function in microscope?

Answer 13

It supports the entire microscope and it also contains light sources in modern designs

Question 14

Arm function in microscope?

Answer 14

It supports the body tube and connects to base it is also used for carrying the microscope

Question 15

It is a large knob for initial focusing by moving the stage or objectives up and down

Answer 15

Course adjustment knob

Question 16

It is a small knob for fine tuning the focus especially on their high and oil immersion objectives

Answer 16

Fine adjustment knob

Question 17

What is the use of scanner in microscope

Answer 17

It gives broad field of view and is also used for locating specimen although not much detail but is still good for orientation

Question 18

What is the use of low power objective in microscope

Answer 18

The low power objective lens is used to locate and get an initial overview of a specimen under the microscope because it provides a wide field of view with low magnification.

This broad perspective allows the user to scan large areas of a slide and identify specific regions of interest before switching to a higher magnification objective for detailed analysis.

It has a narrower field of view and greater detail it is used generally for a general observation of cell groups and structures

Question 19

What is the use of high power objective in microscope

Answer 19

This has further magnification and smaller field of view

but it allows the study of finer details like cell shape, arrangement, and internal features

Question 20

This is the highest magnification with greatest detail and resolution it is used for observing bacteria and minute cell structures and it requires the use of oil to improve clarity

Answer 20

Oil immersion objective

Question 21

Define mordant, counterstain, and gram variable

Answer 21

A mordant - it is a chemical that helps fix or strengthen the attachment of the primary dye to the bacterial cell wall, in gram staining, iodine acts as this and forms a complex with crystal violet.

A counterstain - on the other hand is a secondary dye used after decolorization to provide contrast; in gram staining safranin is used as a counterstain for instance

A gram variable - it refers to a bacteria that do not consistently stain as strictly gram positive or gram negative and under microscope some cells of the same species appear purple while other appear pink

;and this can happen due to several reasons like cell wall structure age of culture damage and cell wall integrity or some are just truly ground variable like Gardnerella vaginalis

Question 22

What is the difference between resolving power and parfocal

Answer 22

Resolving power is the ability of a microscope to distinguish two closely situated objects as separate and it depends on the wavelength of light and numerical aperture of lens

Meanwhile parfocal is the property of a microscope wherein once the specimen is in focus under lpo it remains nearly in focus when switching to higher magnification

Question 23

What is the difference between focal length and numerical aperture

Answer 23

Focal length is the distance between the center of the lens and the point where it brings light rays into focus; the shorter the focal length the higher its magnification.

Meanwhile a numerical aperture is the measure of the light gathering capacity of lens determining resolution and the higher the numerical aperture the better the resolving power

Question 24

Differentiate bright field from dark field microscopy

Answer 24

Bright field microscopics where the field of view is brightly illuminated the specimen is then dark because it absorbs incidence light and it is best for stained specimen on the other hand dark field microscopy produces a dark background in the field of view and the specimen is bright because it reflects scattered light

Question 25

What is the purpose of the oil when using the oil immersion objective

Answer 25

Immersion oil reduces the fraction of light between the slide and objective lens by matching the refractive index of glass hence this increases the amount of light entering the objective lens which improves the resolution and clarity at high magnification

Question 26

What is the characteristics of this following: What is the focal length of low power, high power, and oil immersion

Answer 26

16 mm for low power then for high power it's 4mm and for all immersion it's 1.8 mm

Question 27

The numerical aperture of low power, high power, oil immersion

Answer 27

Low power 0.25 high power 0.65 oil immersion 1.25

Question 29

What is the diameter of the front lens of low power, high power, and all

Answer 29

Low power 5 to 6 mm for high power 1 mm, and for oil immersion its 0.9 mm

Question 30

What is the working distance in mm for low power, high power and oil immersion

Answer 30

For low power 4 to 8 mm for high power 0.5 to 0.7 mm, and for oil immersion 0.1 mm (Based on ppt)

Question 31

Other features for low power ,high power, and oil immersion like their color band, length, lens opening

Answer 31

For low power they're usually yellow band, has a short tube and wide lens opening For high power they usually have a blue band, longer tube and smaller opening For all immersion they usually have a white band, a longest tube and requires immersion of oil or oil immersion