Bacterial Growth Requirements and Gram Staining

Question 1

What ingredient converts liquid to solid medium?

Answer 1

Agar

Question 2

Medium that inhibits growth of certain organisms and permits growth of others.

Answer 2

Selective Media

Question 3

Medium that gives colonies of a particular organism a distinct appearance (makes them all look different).

Answer 3

Differential Media

Question 4

Medium that contains complexed materials that certain fastidious organisms require to grow.

Answer 4

Enrichment Media

Question 5

Gram staining: Primary stain (applied first)

Answer 5

Crystal Violet

Question 6

Gram staining: Mordant

Answer 6

Iodine

Question 7

Gram staining: Decolorizer

Answer 7

Acetone/Alcohol

Question 8

Gram staining: Counter Stain

Answer 8

Safranin

Question 9

What color is Gram Stain?

Answer 9

Purple–resist decolorization and keep the primary stain

Question 10

What color is Gram Negative?

Answer 10

Red–Easily decolorized - take up counter stain

Question 11

Bacteria that cannot grow in the presence of free oxygen (cannot tolerate).

Answer 11

Anaerobe

Question 12

Basically an aerobe but can grow in the absence of free oxygen (survive a wide range of conditions - hard to kill off)

Answer 12

Facultative Anaerobe

Question 13

Can grow only in the complete absence of free oxygen (very difficult to grow - fussy)

Answer 13

Obligate Anaerobe

Question 14

What pH is best for bacterial growth?

Answer 14

pH 7 - can tolerate a narrow range from 6 - 8

Question 15

What is the best time to use bacterial cultures for lab studies?

Answer 15

18 - 24 hours

Question 16

Toxins that are released when the cell is destroyed, because they are bound to the cell wall.

Answer 16

Endotoxins

Gram Negative

Question 17

Extremely delicate, difficult to culture, and involving specialized growth requirements.

Answer 17

Fastidious

Question 18

The interval of time between the invasion by a pathogenic microorganism and the appearance of first symptom of disease.

Answer 18

Incubation period

Question 19

The natural ability of an organism to remain unaffected by harmful substances in its environment.

Answer 19

Resistance

Question 20

Material spread on a slide for microscopic examination.

Answer 20

Smear

Question 21

The process of inculating a culture to provide for the growth of colonies on the surface of a solid medium. Streaking is accomplished by skimming a wire inoculating loop that contains the specimen across the surface of the medium using a back/forth motion.

Answer 21

Streaking

Question 22

An exotoxin produced by beta-hemolytic streptococci, which completely hemolyzes red blood cells.

Answer 22

Streptolysin

Question 23

Easily affected, lacking resistance.

Answer 23

Susceptible

Question 24

capable of of growing in absence of organic compounds; self-nourishing

Answer 24

autotrophic

Question 25

virus that attacks bacteria

Answer 25

bacteriophage

Question 26

organism living on decaying/dead organic matter

Answer 26

saprophyte

Question 27

relative power of a pathogen to cause disease

Answer 27

virulence