MCQs “ Multiple-Choice

Microbiology MICROBIOLOGYQuestionsLAB“
(MCQs)

Question 1: What is a culture medium?

A. A liquid or gel for microorganism growth

B. A substance to kill bacteria

C. A chemical used for DNA testing

D. A tool for measuring pH

Answer: A liquid or gel for microorganism growth

Reference: Page 1

Question 2: Which of the following is NOT a step in preparing culture media?

A. Mixing ingredients with deionized water

B. Using a centrifuge to separate nutrients

C. Sterilizing with an autoclave

D. Labeling the container

Answer: Using a centrifuge to separate nutrients

Reference: Page 2

Question 3: What is the optimal condition for autoclaving?

A. 121°C, 15?30 min, 15 pounds/inch²

B. 100°C, 10 min, atmospheric pressure

C. 200°C, 30 min, high pressure

D. 80°C, 5 min, low pressure

Answer: 121°C, 15?30 min, 15 pounds/inch²

Reference: Page 3

Question 4: What is the purpose of the streak plate method?

A. To isolate a pure strain of bacteria

C. To create antibiotic-resistant bacteria

D. To prepare liquid media

Answer: To isolate a pure strain of bacteria

Reference: Page 5

Question 5: What does the Kirby-Bauer disk diffusion method measure?

A. Bacterial motility

B. Antibiotic susceptibility

C. Enzyme activity

D. Growth temperature tolerance

Answer: Antibiotic susceptibility

Reference: Page 6

Question 6: What type of media is blood agar?

A. Selective

B. Differential

C. Enrichment

D. Synthetic

Answer: Enrichment

Reference: Page 7

Question 7: What does MacConkey agar test for?

A. Gram-positive bacteria

B. Lactose fermentation in gram-negative bacteria

C. Presence of hemolysis

D. Antibiotic resistance

Answer: Lactose fermentation in gram-negative bacteria

Question 8: What is a positive result in the catalase test?

A. Gas bubbles form

B. Color changes to yellow

C. Zone of inhibition forms

D. No bacterial growth

Answer: Gas bubbles form

Reference: Page 11

Question 9: Which hemolysis type causes green discoloration?

A. Alpha-hemolysis

B. Beta-hemolysis

C. Gamma-hemolysis

D. Delta-hemolysis

Answer: Alpha-hemolysis

Reference: Page 15

Question 10: Which bacteria are lactose fermenters?

A. E. coli and Klebsiella

B. Proteus and Salmonella

C. Shigella and Pseudomonas

D. Staphylococcus and Streptococcus

Answer: E. coli and Klebsiella

Reference: Page 19
 C. To label the media containers

D. To detect bacterial contamination

Answer: To indicate sterilization temperature has been reached

Reference: Page 3

Question 12: What is the purpose of enrichment media?

A. To support fastidious organism growth

B. To inhibit bacterial growth

C. To isolate gram-negative bacteria

D. To distinguish between species visually

Answer: To support fastidious organism growth

Reference: Page 7

Question 13: Which media is both selective and differential?

A. MacConkey agar

B. Blood agar

C. Mueller-Hinton agar

D. Nutrient agar

Answer: MacConkey agar

Reference: Page 9

Question 14: What causes the color change in Mannitol Salt Agar (MSA)?

A. Fermentation of mannitol producing acid

B. Presence of hemolysis

C. High salt concentration

D. Degradation of proteins

Answer: Fermentation of mannitol producing acid

Reference: Page 12
Question 15: Which bacteria produces yellow colonies on Mannitol Salt Agar?

A. Staphylococcus aureus

B. E. coli

C. Staphylococcus epidermidis

D. Klebsiella pneumoniae

Answer: Staphylococcus aureus

Reference: Page 12

Question 16: What is the role of the coagulase test?

A. To differentiate Staphylococcus aureus from other species

B. To identify gram-negative bacteria

C. To test lactose fermentation

D. To detect antibiotic susceptibility

Answer: To differentiate Staphylococcus aureus from other species

Reference: Page 13

Question 17: Which Streptococcus species causes complete hemolysis?

A. Streptococcus pyogenes

B. Streptococcus pneumoniae

C. Streptococcus viridans

D. Enterococcus faecalis

Answer: Streptococcus pyogenes

Reference: Page 15

Question 18: What is the characteristic appearance of Proteus species on blood agar?

A. Swarming motility

B. Green discoloration

C. Yellow colonies
 D. No visible growth

Answer: Swarming motility

Reference: Page 19

Question 19: What pigment does Pseudomonas aeruginosa produce?

A. Pyocyanin (blue-green)

B. Yellow colonies

C. Rose-red colonies

D. White colonies

Answer: Pyocyanin (blue-green)

Reference: Page 20

Question 20: What test is used to differentiate between Streptococcus pneumoniae and Streptococcus virida

A. Optochin test

B. Catalase test

C. Coagulase test

D. Bile-esculin test

Answer: Optochin test

Reference: Page 21

Question 21: What does the bile-esculin test detect?

A. Enterococcus species

B. Lactose fermenters

C. Hemolytic activity

D. Antibiotic susceptibility

Answer: Enterococcus species

Reference: Page 23

Question 22: Which media prevents swarming of Proteus species?

B. Blood agar

C. Mueller-Hinton agar

D. Mannitol salt agar

Answer: MacConkey and CLED agar

Reference: Page 20

Question 23: Which media is used for testing antibiotic susceptibility?

A. Mueller-Hinton agar

B. MacConkey agar

C. Blood agar

D. Mannitol salt agar

Answer: Mueller-Hinton agar

Reference: Page 6

Question 24: Which bacteria are oxidase positive?

A. Pseudomonas aeruginosa

B. E. coli

C. Staphylococcus aureus

D. Proteus species

Answer: Pseudomonas aeruginosa

Reference: Page 20

Question 25: What is the turbidity standard for Kirby-Bauer testing?

A. 0.5 McFarland standard

B. 1.0 McFarland standard

C. 5.0 McFarland standard

D. 2.5 McFarland standard

Reference: Page 6

Question 26: What are the conditions for storing agar plates?

A. Inverted position in a refrigerator

B. Upright position at room temperature

C. Inverted position in an incubator

D. Flat position in a freezer

Answer: Inverted position in a refrigerator

Reference: Page 3

Question 27: What is chocolate agar used for?

A. To grow fastidious bacteria like Haemophilus influenzae

B. To differentiate gram-positive cocci

C. To test antibiotic susceptibility

D. To isolate gram-negative bacteria

Answer: To grow fastidious bacteria like Haemophilus influenzae

Reference: Page 7

Question 28: What is the role of selective media?

A. To inhibit the growth of some organisms while allowing others to grow

B. To visually distinguish between species

C. To support fastidious organism growth

D. To sterilize bacterial cultures

Answer: To inhibit the growth of some organisms while allowing others to grow

Reference: Page 7

Question 29: What color colonies indicate lactose fermentation on MacConkey agar?

A. Pink to red colonies

C. Green colonies

D. Colorless colonies

Answer: Pink to red colonies

Reference: Page 9

Question 30: What is a zone of inhibition?

A. An area around an antibiotic disc where bacteria do not grow

B. A region of increased bacterial growth

C. The edge of a bacterial colony

D. The center of a blood agar plate

Answer: An area around an antibiotic disc where bacteria do not grow

Reference: Page 6

‫ “ما من مسلم يدعو اهلل بدعوة ليس فيها‬:‫ فقال‬،‫حثنا الرسول ـ ﷺ ـ على الدعاء‬
‫ و إما أن‬،‫ إما أن تعجل له دعوته‬:‫إثم وال قطيعة رحم إال أعطاه اهلل بها إحدى ثالث‬
‫ إذًا نكثر‬:‫ و إما أن يصرف عنه من السوء مثلها” قالوا‬،‫يدخرها له في اآلخرة‬
(‫ )رواه أحمد‬.”‫” اهلل أكثر‬:‫ قال‬،‫الدعاء‬