Lab Quiz 4

Question 1

What is staining used for?

Answer 1

enhance contrast between the sample and its surroundings

Question 2

Direct stain

Answer 2

stains/colors the organism

Question 3

Indirect stain

Answer 3

stains the background (everything but the sample)

Question 4

Simple stain

Answer 4

Uses only one stain

Question 5

What can a simple stain determine?

Answer 5

cell morphology
size
arrangement

Question 6

Differential staining used in this lab

Answer 6

Gram stain
spore stain

Question 7

Gram Staining

Answer 7

stains cell envelope or peripheral structure

Question 8

spore staining

Answer 8

stains endospores

Question 9

Gram positive bacterial cells

Answer 9

retains crystal violet- purple
thick peptidoglycan layer

Question 10

Gram negative bacterial cells

Answer 10

crystal violet washes out
retains safranin counterstain-pink
outer membrane and a thin layer of peptidoglycan

Question 11

Gram stain procedure

Answer 11

C- crystal violet
R- rinse
I- iodine
E- ethanol
S- safranin

Question 12

When do somme bacteria sporulate

Answer 12

under environmental stress
EX limited carbon source

Question 13

How do we create environmental stress to form endospores in lab?

Answer 13

nutrient agar places without glucose
this limits carbon source

Question 14

Spore positive bacteria

Answer 14

retain malachite green

Question 15

Spore negative bacteria

Answer 15

safranin stains membrane of vegatative cells
pink

Question 16

vegatative cells

Answer 16

cells that do not take part in production of gametes

Question 17

Spore stain formation

Answer 17

weeklong starvation from growing on NA-agar plate without carbon source

Question 18

Spore stain procedure

Answer 18

M- apply malachite green
M- mordant (heat)
W- application of water (decolorized)
S- Safranin (counter stain)

Question 19

Total magnification

Answer 19

Lens times ocular

Question 20

How many on/off switches on microscope?

Answer 20

three
- microscope
- camera
- display

Question 21

What are the causative agents of bacillary dysentery and typhoid fever?

Answer 21

Shigella
Salmonella

Question 22

Do not screen for pathogens, WHY and WHAT DO YOU SCREEN

Answer 22

when pathogens are detected its too late to prevent spread of disease
Instead screen for indicator organisms that are highly abundant in feces

Question 23

What is the most frequently used indicator organism

Answer 23

coliforms

Question 24

Coliforms

Answer 24

facultative anaerobes
gram negative
rod shaped
lactose fermenters

Question 25

Where are coliforms found?

Answer 25

colon and feces of healthy individuals the gastrointestinal tract of other animals

Question 26

What are coliforms used as an index for

Answer 26

contamination of Shigella and Salmonella safety of marine and estuary waters used for shell fishing safety of freshwater and marine swimming areas

Question 27

Heterotrophic Plate Count

Answer 27

quantitative determines overall quality of water and effectiveness of disinfectants used

Question 28

HPC coliforms are detected in two stages

Answer 28

Presumptive test confirmed test

Question 29

Presumptive test

Answer 29

uses selective/differential Lauryl-tryptose (LT) broth

Question 30

LT broth

Answer 30

contains lauryl-sulfate- detergent contains lactose- supports coliform growth by fermentation

Question 31

T/F most bacteria can pass through detergents

Answer 31

FALSE only bacteria in stomach and intestinal tract can withstand detergent

Question 32

Confirmed test

Answer 32

streaked on Eosin-methylene blue (EMB) agar to verify presence of coliforms

Question 33

EMB agar

Answer 33

selective- contains dyes that inhibit gram-positive organisms differential- lactose fermenters form dark colored colonies

Question 34

Most probable number (MPN)

Answer 34

statistical estimate used to calculate number of coliforms based off LT tube test

Question 35

How many dilutions per sample for MPN

Answer 35

two

Question 36

Membrane filtration technique

Answer 36

known volume of water is filtered through thin membrane grid (0.45 um)

Question 37

Membrane filtration process

Answer 37

all bacteria are retained on filter's surface this is immediately transferred to a plate plate is incubated 32 C dissecting microscope characteristic coliform colonies are counted the number of colonies per ml is calculated

Question 38

Indigenous/normal flora

Answer 38

microorganisms found in many regions of the body

Question 39

Folmites

Answer 39

inanimate/inert objects that are likely to carry infection EX. doorknob

Question 40

Why is skin hospitable?

Answer 40

Skin is very dry salts create hypertonic environment sebaceous glands secrete oil/acids that inhibit bacterial growth

Question 41

Most skin bacteria are...

Answer 41

Gram positive salt tolerant cocci catalase positive EX staphylococcus and micrococcus

Question 42

What is causative agent of staph infections?

Answer 42

staphylococcus aereus

Question 43

S. aereus will ferment....

Answer 43

mannitol

Question 44

What agar is used to differentiate and select S. aureus

Answer 44

mannitol salt agar

Question 45

Pathogenic strains of S. aureus typically produce...

Answer 45

coagulase causes fibrin in blood to clot

Question 46

Common genre that can grow in throat

Answer 46

Streptococcus and staphylococcus

Question 47

Causitive agent of strep throat

Answer 47

Streptococcus pyogenes

Question 48

Pathogenic streptococcal species typically produce what?

Answer 48

enzyme called streptolysins causes cell lysis

Question 49

hemolysis

Answer 49

When blood cells are being attack by lysis

Question 50

How is hemolysis determined

Answer 50

streaking bacteria on plates of blood agar

Question 51

Three patterns of hemolytic activity

Answer 51

alpha beta gamma

Question 52

alpha hemolysis

Answer 52

partial hemolysis characterized by green cloudy zone around bacterial growth

Question 53

beta hemolysis

Answer 53

complete lysis characterized by clear zone around growth

Question 54

gamma hemolysis

Answer 54

no hemolysis characterized by no change on blood agar

Question 55

T/F streptococci can grow in presence of respiratory poisons

Answer 55

TRUE because they lack a respiratory chain

Question 56

What out of the three types of hemolysis are pathogenic

Answer 56

Beta hemolytic streptococci

Question 57

What out of the three types of hemolysis are part of normal flora

Answer 57

alpha and gamma hemolytic streptococci

Question 58

What are ways streptococcus aureus can be spread?

Answer 58

direct and indirect contact