Microbiology Lab Test 1 Questions and
Answers 100% Pass
What is the purpose of using a spectrophotometer in microbiology?
✔✔To measure the turbidity of a bacterial culture.
What does a positive phenylalanine deaminase test indicate?
✔✔The organism can deaminate phenylalanine to produce phenylpyruvic acid.
What is the term for bacteria that grow at pH levels below 4.5?
✔✔Acidophiles.
What is the primary purpose of the Kirby-Bauer test?
✔✔To evaluate bacterial susceptibility to antibiotics.
What is the main advantage of using an enrichment culture technique?
✔✔To promote the growth of a specific microorganism from a mixed population.
1
,What is the appearance of lactose-fermenting bacteria on EMB (eosin methylene blue) agar?
✔✔Colonies with a metallic green sheen or dark centers.
What does a positive gelatin hydrolysis test suggest about an organism?
✔✔It produces gelatinase, an enzyme that breaks down gelatin.
What is the function of the ocular lens in a microscope?
✔✔To magnify the image produced by the objective lens.
What does a pink result in a urea hydrolysis test signify?
✔✔The production of ammonia and an alkaline pH.
What is the main role of coagulase in pathogenic bacteria?
✔✔To clot plasma, which may help evade host immune defenses.
What is the morphology of coccobacilli?
✔✔Short, oval-shaped rods.
2
,What does a color change in a carbohydrate fermentation test indicate?
✔✔Acid production from sugar fermentation.
What is the purpose of using eosin and methylene blue in EMB agar?
✔✔To differentiate lactose fermenters from non-fermenters and inhibit Gram-positive bacteria.
What is the term for organisms that grow best under moderate salt conditions?
✔✔Halotolerant.
What does a positive sulfur reduction test in SIM medium indicate?
✔✔The production of hydrogen sulfide.
What is the purpose of the methyl red test?
✔✔To detect mixed acid fermentation in bacteria.
What is the appearance of a positive starch hydrolysis test?
✔✔A clear zone around the bacterial growth after iodine application.
3
, What is the function of peptidoglycan in bacterial cell walls?
✔✔To provide structural support and shape.
What does a positive Voges-Proskauer test signify?
✔✔The production of acetoin from glucose fermentation.
What is the term for bacteria that grow in the presence of very high salt concentrations?
✔✔Extreme halophiles.
What is the purpose of using nutrient broth in microbiology?
✔✔To support the growth of a wide variety of microorganisms.
What does a positive result in the DNase test look like?
✔✔A clear zone around the bacterial growth after adding hydrochloric acid.
What is the main function of the catalase enzyme?
✔✔To break down hydrogen peroxide into water and oxygen.
4
Answers 100% Pass
What is the purpose of using a spectrophotometer in microbiology?
✔✔To measure the turbidity of a bacterial culture.
What does a positive phenylalanine deaminase test indicate?
✔✔The organism can deaminate phenylalanine to produce phenylpyruvic acid.
What is the term for bacteria that grow at pH levels below 4.5?
✔✔Acidophiles.
What is the primary purpose of the Kirby-Bauer test?
✔✔To evaluate bacterial susceptibility to antibiotics.
What is the main advantage of using an enrichment culture technique?
✔✔To promote the growth of a specific microorganism from a mixed population.
1
,What is the appearance of lactose-fermenting bacteria on EMB (eosin methylene blue) agar?
✔✔Colonies with a metallic green sheen or dark centers.
What does a positive gelatin hydrolysis test suggest about an organism?
✔✔It produces gelatinase, an enzyme that breaks down gelatin.
What is the function of the ocular lens in a microscope?
✔✔To magnify the image produced by the objective lens.
What does a pink result in a urea hydrolysis test signify?
✔✔The production of ammonia and an alkaline pH.
What is the main role of coagulase in pathogenic bacteria?
✔✔To clot plasma, which may help evade host immune defenses.
What is the morphology of coccobacilli?
✔✔Short, oval-shaped rods.
2
,What does a color change in a carbohydrate fermentation test indicate?
✔✔Acid production from sugar fermentation.
What is the purpose of using eosin and methylene blue in EMB agar?
✔✔To differentiate lactose fermenters from non-fermenters and inhibit Gram-positive bacteria.
What is the term for organisms that grow best under moderate salt conditions?
✔✔Halotolerant.
What does a positive sulfur reduction test in SIM medium indicate?
✔✔The production of hydrogen sulfide.
What is the purpose of the methyl red test?
✔✔To detect mixed acid fermentation in bacteria.
What is the appearance of a positive starch hydrolysis test?
✔✔A clear zone around the bacterial growth after iodine application.
3
, What is the function of peptidoglycan in bacterial cell walls?
✔✔To provide structural support and shape.
What does a positive Voges-Proskauer test signify?
✔✔The production of acetoin from glucose fermentation.
What is the term for bacteria that grow in the presence of very high salt concentrations?
✔✔Extreme halophiles.
What is the purpose of using nutrient broth in microbiology?
✔✔To support the growth of a wide variety of microorganisms.
What does a positive result in the DNase test look like?
✔✔A clear zone around the bacterial growth after adding hydrochloric acid.
What is the main function of the catalase enzyme?
✔✔To break down hydrogen peroxide into water and oxygen.
4
