chapter 3

Question 1

the microscopes two key characteristics are

Answer 1

magnification and resolving power

Question 2

magnification in two phases

Answer 2

1- objective lens forms the magnified real image
2- the real image is projected to the ocular where it is magnified again to form the virtual image

Question 3

total magnification is the product of

Answer 3

the separate magnifying powers of 2 lenses

Question 4

forumla for total magnification

Answer 4

objective power times ocular power

Question 5

resolution is the capacity to distinguish

Answer 5

2 adjacent objects and it depends on the wavelength of light that forms

Question 6

resolving power formula

Answer 6

wavelength of light over 2 times the numerical aperture of objective lens

Question 7

visible light wavelength is

Answer 7

400-700 nm

Question 8

numerical aperture of lens ranges from

Answer 8

0.1 to 1.25

Question 9

bright field (most common)

Answer 9

specimen is darker than surrounding field
used for live and preserved stained specimens

Question 10

dark-field

Answer 10

brightly illuminated specimens surrounded by dark
used for live and unstained specimens

Question 11

phase contrast

Answer 11

transforms subtle changes in light waves passing through the specimen into differences in light intensity
best for observing intracellular structures

Question 12

fluorescence microscope

Answer 12

modified with an ultraviolet radiation source and filter
useful in diagnosing infections

Question 13

scanning confocal microscope

Answer 13

uses a laser beam of light to scan the specimen
allows focus on multiple depths

Question 14

electron microscopy

Answer 14

forms an image with a beam of electrons that can be made to travel in wavelike patterns when at high speeds

Question 15

electron waves are 100,00x

Answer 15

shorter than visible light

Question 16

transmission electron microscopes

Answer 16

transmit electrons thru specimen
dark=thicker
light= less dense

Question 17

scanning electron microscope

Answer 17

allows 3-D view

Question 18

wet amounts and hanging drop amounts

Answer 18

allow examination of characteristics of live cells

Question 19

fixed amounts

Answer 19

made y drying and heating a film of specimen

Question 20

basic dyes

Answer 20

cationic, positively charged

Question 21

positive staining

Answer 21

negatively charged and attract basic dyes

Question 22

acid dyes are

Answer 22

anionic negatively charged chromophore

Question 23

negative staining

Answer 23

microbe repels dye, dye stains background

Question 24

simple stains

Answer 24

one dye is used
reveals shape, size and arrangement

Question 25

differential stains

Answer 25

use primary stain and a counterstain to distinguish cell types or parts

Question 26

structural stains

Answer 26

reveal certain cell parts not revealed by conventional methods capsule and flagellar stains

Question 27

6 I's of culturing microbes

Answer 27

inoculation(sample into container) isolation(separating one species from another) incubation(under conditions that allow growth) inspection information gathering identification

Question 28

A colony forms if an individual bacterial cell is

Answer 28

separated from other cells and has space on a nutrient dense surface

Question 29

ways to identify a microbe

Answer 29

cell and colony morphology or staining characteristics DNA sequence biochemical tests immunological tests

Question 30

media is classified into three properties

Answer 30

physical state- liquid, semisolid, and solid chemical composition- synthetic and complex functional type

Question 31

the most commonly used solidifying agent

Answer 31

agar

Question 32

agar provides framework to

Answer 32

hold moisture and nutrients and is not digestible

Question 33

nutrient broth is a liquid medium containing

Answer 33

beef extract and peptone

Question 34

nutrient agar is solid media containing

Answer 34

beef extract, peptone, agar

Question 35

chemical synthetic media contains pure

Answer 35

organic and inorganic compounds in an exact chemical formula

Question 36

chemical complex media contains at least one

Answer 36

ingredient that is not chemically definable

Question 37

general purpose media grows a broad range of

Answer 37

microbes, usually complex

Question 38

enriched media contains complex organic substances like

Answer 38

blood, serum, hemoglobin, or special growth factors required by fastidious microbes

Question 39

selective media contains one or more agents that

Answer 39

inhibit growth of some microbes and encourage growth of the desired microbes

Question 40

differential media allows growth of

Answer 40

several types of microbes and displays visible differences among those microbes

Question 41

carbohydrate fermentation medium contains

Answer 41

sugars that can be fermented, converted to acids, and a pH indicator to show this reaction