Yersinia Selective Agar MCQs Mock Test

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Explore the Mock Test of Yersinia Selective Agar MCQs! Learn its uses, preparation, colony morphology, and how it isolates Yersinia enterocolitica and Y. pseudotuberculosis. Covers pH, antibiotics, cold enrichment, ISO standards, and key differentiators from MacConkey Agar. Perfect for microbiology students & lab professionals!

Read the Full Article 50 FAQs and 30 MCQs >>

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Microbiology Department

Yersinia Selective Agar MCQs Mock Test

Explore Yersinia Selective Agar with 50 FAQs & 30 MCQs! Learn its uses, preparation, colony morphology, and how it isolates Yersinia enterocolitica and Y. pseudotuberculosis. Covers pH, antibiotics, cold enrichment, ISO standards, and key differentiators from MacConkey Agar. Perfect for microbiology students & lab professionals!

Key Features Covered:
✔ Selective & Differential Medium
✔ Mannitol Fermentation (Bulls-eye Colonies)
✔ Cold Enrichment & Incubation Tips
✔ Antibiotics (Cefsulodin, Novobiocin)
✔ Clinical & Food Testing Applications
✔ MCQs for Exam Prep

Ideal for: Medical labs, food safety, and microbiology studies.

Read Full Article: Yersinia Selective Agar 50 FAQs and 30 MCQs

1 / 30

Category: Clinical Laboratory

What indicates mannitol fermentation on Yersinia Selective Agar?

Black colonies

Blue-green colonies

Yellow colonies

Dark pink/red colonies with a bulls-eye appearance

2 / 30

Category: Clinical Laboratory

Which animal is a major reservoir for Y. enterocolitica?

Cows

Chickens

Pigs

Fish

3 / 30

Category: Clinical Laboratory

Which disease is NOT caused by Yersinia enterocolitica?

Lymphadenopathy

Gastroenteritis

Pneumonia

Bubonic plague (Y. pestis causes plague)

4 / 30

Category: Clinical Laboratory

How is Yersinia Selective Agar sterilized?

Boiling for 5 minutes

UV radiation

Filtration

Autoclaving at 121°C for 15 minutes

5 / 30

Category: Clinical Laboratory

Which sugar is used as a fermentable substrate in this medium?

Glucose

Mannitol

Lactose

Sucrose

6 / 30

Category: Clinical Laboratory

Why are cefsulodin and novobiocin added?

To neutralize toxins

To increase selectivity for Yersinia

To enhance pigment production

To solidify the medium

7 / 30

Category: Clinical Laboratory

What is the role of neutral red in the agar?

pH indicator (red at pH <6.8)

Antibiotic

Bile salt

Nutrient source

8 / 30

Category: Clinical Laboratory

Which ingredient stimulates Yersinia growth?

Crystal violet

Agar

Sodium pyruvate

Sodium chloride

9 / 30

Category: Clinical Laboratory

Which component inhibits Gram-positive bacteria?

Magnesium sulfate

Sodium chloride

Neutral red

Sodium deoxycholate and crystal violet

10 / 30

Category: Clinical Laboratory

If non-Yersinia bacteria grow, what could be the issue?

Overheating

Antibiotics not added

Incorrect pH

Too much agar

11 / 30

Category: Clinical Laboratory

How do Y. enterocolitica colonies appear?

Mucoid and yellow

Green metallic sheen

Dark pink centers with translucent borders (bulls-eye)

Black with H₂S production

12 / 30

Category: Clinical Laboratory

Which organism grows with dark pink centers but no translucent zone?

Y. pestis

E. coli

Y. pseudotuberculosis ✔

Proteus mirabilis

13 / 30

Category: Clinical Laboratory

What is the primary purpose of Yersinia Selective Agar?

Detect E. coli O157:H7

Culture Staphylococcus aureus

Isolate Salmonella

Isolate Yersinia enterocolitica and Y. pseudotuberculosis

14 / 30

Category: Clinical Laboratory

At what temperature should antibiotics be added?

45-50°C

70°C

37°C

d) Room temperature

15 / 30

Category: Clinical Laboratory

Which of the following samples can be tested using Yersinia Selective Agar?

Sputum only

Stool, food, and water

Blood only

Urine only

16 / 30

Category: Clinical Laboratory

Which ISO standard recommends Yersinia Selective Agar?

ISO 6888 (Staphylococcus)

ISO 16654 (E. coli)

ISO 6579 (Salmonella)

ISO 10273 (Yersinia)

17 / 30

Category: Clinical Laboratory

Which bacteria may resemble Yersinia on this agar?

Aeromonas and Citrobacter

Clostridium difficile

Neisseria gonorrhoeae

Streptococcus pyogenes

18 / 30

Category: Clinical Laboratory

What is a limitation of this medium?

Inhibits all Gram-negatives

Turns blue on contamination

Cannot detect Y. pestis

Requires anaerobic incubation

19 / 30

Category: Clinical Laboratory

What is a key biochemical test for Y. enterocolitica?

Urease-positive

Oxidase-positive

Indole-positive

Citrate-positive

20 / 30

Category: Clinical Laboratory

Which virulence factor helps Yersinia evade immunity?

Yops (Yersinia outer proteins)

Coagulase

Enterotoxin

Capsule

21 / 30

Category: Clinical Laboratory

How should prepared plates be stored?

-20°C

2-8°C

37°C

Room temperature

22 / 30

Category: Clinical Laboratory

What is the recommended incubation temperature?

15°C

22-32°C

37°C only

42°C

23 / 30

Category: Clinical Laboratory

Who developed Yersinia Selective Agar?

Schiemann

Joseph Lister

Robert Koch

Louis Pasteur

24 / 30

Category: Clinical Laboratory

Cold enrichment works because Yersinia is:

Thermophilic

Halophilic

Acidophilic

Psychrotrophic

25 / 30

Category: Clinical Laboratory

How long can cold enrichment be performed?

Up to 21 days

1 week

48 hours

2 days

26 / 30

Category: Clinical Laboratory

What is the pH of Yersinia Selective Agar?

6.2 ± 0.2

8.0 ± 0.2

7.4 ± 0.2

5.5 ± 0.2

27 / 30

Category: Clinical Laboratory

What confirms Yersinia beyond colony morphology?

Hemolysis on blood agar

Biochemical tests (e.g., urease, motility)

Gram staining (Gram-positive rods)

Spore staining

28 / 30

Category: Clinical Laboratory

What type of medium is Yersinia Selective Agar?

Chromogenic

Transport medium

Selective and differential

Enriched only

29 / 30

Category: Clinical Laboratory

Mannitol-negative organisms produce:

Colorless, translucent colonies

Blue colonies

Swarming growth

Red colonies

30 / 30

Category: Clinical Laboratory

Why is cold enrichment (4°C) used?

To reduce contamination

To kill other bacteria

To enhance Yersinia recovery

To solidify the agar

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Read the Full Article 50 FAQs and 30 MCQs >>

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