Question 1

The biochemical pathway that the methyl red test confirms is

Accepted Answer

A)  glucose $\rightarrow$ pyruvic acid $\rightarrow$ mixed acid fermentation. 
B)  pyruvic acid $\rightarrow$ glucose$\rightarrow$ mixed acid fermentation. 
C)  glucose $\rightarrow$ pyruvic acid $\rightarrow$ acetoin $\rightarrow$ diacetyl KOH. 
D)  butylene $\rightarrow$ pyruvic acid $\rightarrow$ diacetyl KOH.

Question 2

Extracellular DNase can be produced by

Accepted Answer

A)  Staphylococcus aureus. 
B)  Streptococcus agalactiae. 
C)  Micrococcus luteus. 
D)  Haemophilus influenzae.

Question 3

Bacteria can use carbohydrates by

Accepted Answer

A)  oxidation. 
B)  synthesis. 
C)  reduction. 
D)  induction.

Question 4

To inoculate TSI agar or Kligler iron agar (KIA), the laboratory scientist should pick a well-isolated colony with an inoculating needle and

Accepted Answer

A)  touch the bottom of the needle to the bottom of the slant portion of the agar and move the needle back and forth across the surface of the slant all the way to the top of the tube. 
B)  touch the bottom of the needle to the top of the slant portion of the agar and move the needle back and forth across the surface of the slant all the way to the bottom of the tube. 
C)  touch the bottom of the needle to the bottom of the slant portion of the agar and move the needle up the slant in a straight line all the way to the top of the tube. 
D)  stab the butt almost all the way to the bottom of the tube, then move the needle back and forth over the surface of the slant all the way to the top of the tube.

Question 5

The initial screening of gram-negative rods is done by testing for the use of this carbohydrate.

Accepted Answer

A)  Glucose 
B)  Sucrose 
C)  Lactose 
D)  Mannitol

Question 6

The LIA slant is also useful in differentiating

Accepted Answer

A)  Acinetobacter and Alcaligenes. 
B)  Klebsiella and Enterobacteriaceae. 
C)  Proteus, Morganella, and Providencia. 
D)  Escherichia, Salmonella, and Campylobacter.

Question 7

What advantage do the methods based on enzyme substrates have over conventional methods?

Accepted Answer

A)  They use filter paper as the structure to hold the bacteria. 
B)  They reduce the amount of substrate needed for the reactions. 
C)  They use fluorogenic substrates. 
D)  They do not require growth of the organism in the system.

Question 8

A bacterial DNase is

Accepted Answer

A)  an oligonucleotide formed from a native DNA. 
B)  an oligonucleotide formed from a native RNA. 
C)  a proteolytic enzyme that forms extracellular DNA in the bacterial cell. 
D)  an endonuclease that cleaves internal phosphodiester bonds, resulting in smaller subunits of DNA.

Question 9

Rapid identification of clinical isolates often involves commercially packaged identification kits and fully automated instruments. What do these kits use to assess the preformed bacterial enzymes?

Accepted Answer

A)  Extraction kits 
B)  Volatile benzenes 
C)  Chromogenic or fluorogenic substrates 
D)  Chemiluminescent substrates

Question 10

If a bacterium utilizes lactose or sucrose and produces H2S, what will the TSI reaction look like?

Accepted Answer

A)  Acid/acid, black butt 
B)  Acid/alkaline, black butt 
C)  Alkaline/alkaline, black slant 
D)  Alkaline/acid, black slant

Question 11

The chemical reaction for the ONPG test is

Accepted Answer

A)  $\beta$-galactosidase hydrolyzes lactose into glucose and galactose 
B)  glucose -> pyruvic acid -> acetoin 
C)  $\beta$-galactosidase hydrolyzes ONPG into galactose and o-nitrophenol (a yellow compound) 
D)  ONPG is oxidized into acetoin and glucose

Question 12

What does a lysine iron agar (LIA) slant contain?

Accepted Answer

A)  Ornithine, glucose, ferric ammonium chloride, and urea 
B)  Lysine, glucose, ferric ammonium citrate, and sodium thiosulfate 
C)  Acetoin, pyruvic acid, nitrate, and sulfanilic acid 
D)  Arginine, lactose, ferric chloride, sodium hydroxide, and urea

Question 13

If a bacterium utilizes lactose or sucrose, what will the TSI reaction look like?

Accepted Answer

A)  Alkaline/acid 
B)  Alkaline/alkaline 
C)  Acid/acid 
D)  Acid/alkaline

Question 14

Amino acids can be metabolized by these substances that remove an amine group. What is this substance?

Accepted Answer

A)  Amino acidase 
B)  Amylase 
C)  Deaminase 
D)  Decarboxylase

Question 15

Nucleic acid assays are based on the _____ of the organism and are believed to be more accurate.

Accepted Answer

A)  phenotype 
B)  genotype 
C)  plasmid 
D)  lysogeny

Question 16

How are organisms identified with commercial identification kits?

Accepted Answer

A)  Numeric codes 
B)  Color codes 
C)  Alphabetic codes 
D)  Alphanumeric codes

Question 17

What does the oxidase test determine?

Accepted Answer

A)  If the bacteria have the enzyme, oxidase, to reduce oxygen to carbon dioxide 
B)  If the bacteria have oxidase, which will allow for the oxidation of carbohydrates 
C)  If the bacteria can hydrolyze urea to ammonia and carbon dioxide 
D)  The presence of the cytochrome oxidase system that oxidizes reduced cytochrome with molecular oxygen

Question 18

Decarboxylase tests exist for all the following amino acids, except

Accepted Answer

A)  lysine. 
B)  tyrosine. 
C)  ornithine. 
D)  arginine.

Question 19

Other sugars used to differentiate bacteria include all of the following, except

Accepted Answer

A)  raffinose. 
B)  arabinose. 
C)  rhamnose. 
D)  sucralose.

Question 20

Some bacteria produce these enzymes that break down gelatin into amino acids. These enzymes are called

Accepted Answer

A)  DNase. 
B)  gelatinase. 
C)  proteolytic. 
D)  malonate.

Exam 9: Biochemical Identification of Gram-Negative Bacteria