Final Exam Ch 2

Question 1

eye peice

Answer 1

1st set of lenses, this is the lense which we look through

Question 2

Revolving nosepiece

Answer 2

used to hold objective lenses

Question 3

objective lenses

Answer 3

2nd set of lenses, used to magnify the specimen

Question 4

coarse focus knob

Answer 4

used for large scale movements, especially with 4x or 10x objective lenses

Question 5

fine focus knob

Answer 5

used for small scale movements with 40x and 100x objective lenses

Question 6

stage

Answer 6

where you keep the specimen on the slide in position

Question 7

illuminator

Answer 7

light source, typically a high-intensity bulb below the stage

Question 8

Diaphragm

Answer 8

reduces or magnifies intensity of light

Question 9

condensor lens

Answer 9

3rd set of lenses, focuses all of the light rays on the specimen to maximize illumination

Question 10

x-y mechanical stage knobs

Answer 10

move the slide that is on stage

Question 11

rheostat

Answer 11

a dimmer switch that controls the intensity of the illuminator

Question 12

simple stain

Answer 12

uses one (basic or acidic) stain on 1 slide

Question 13

differential stain

Answer 13

multiple stains on 1 slide
* example: gram staining & acid-fast staining

Question 14

special stain

Answer 14

staining special structures
* example: endospore, flagella, capsule

Question 15

acidic stain

Answer 15

how do they stain the cell
* have a negative charge
* stain positively charged molecules
* stain background and will not stain the cells/specimen

Question 16

basic stain

Answer 16

how do they stain the cell
* have a positive charge
* they stay negatively charged molecules
* stain the cell/specimen

Question 17

Gram stain steps

Answer 17

• Crystal Violet: primary stain
• Gram’s Iodine: mordant makes dye less soluble so it adheres to sell walls
• Alcohol: decolorizer
• Safranin: counterstain

Question 18

Gram stain for gram positive

Answer 18

• crystal violet: stains cells purple
• iodine: cell remains purple
• alcohol: cells remain purple
• Safranin: cells remain purple

Question 19

Gram stain for gram negative

Answer 19

• Crystal Violet: stains cells purple
• Iodine: cells remain purple
• alcohol: cells become colorless
• Safranin: cells become pink/red

Question 20

Acid fast staining

Answer 20

• used to differentiate between two types of gram-positive cells (those that have waxy mycolic acids in their cell walls and those that do not)
• can be used to detect Mycobacterium tuberculosis

Question 21

What are the magnifications of the three objectives in the microscope?

Answer 21

4X, 10X, 40X, 100X

Question 22

What is total magnification?

Answer 22

Ocular magnification X objective magnification

Question 23

What is the use of oil immersion lens?

Answer 23

To increase resolution and decrease refraction.