YEPD Agar (Yeast Extract Peptone Dextrose) MCQs Mock Test for Lab Professionals & Medical Students

Master the fundamentals of YEPD Agar (Yeast Extract Peptone Dextrose)—a cornerstone medium in yeast and fungal cultivation. This article provides a targeted MCQ mock test (30 questions) for lab professionals and medical students, framed by concise educational content. Test your knowledge of YEPD’s composition, applications, preparation, and troubleshooting, then reinforce learning with post-test key takeaways.

YEPD Agar Fundamentals

What is YEPD Agar?
YEPD Agar is a complex, nutrient-rich medium used primarily for cultivating Saccharomyces cerevisiae and other fungi/yeasts. Its versatility in research, industrial microbiology (e.g., brewing, biotechnology), and diagnostics makes it essential knowledge.

Key Components & Functions:

• Yeast Extract: Supplies B-vitamins, nucleotides, and amino acids.
• Peptone: Provides organic nitrogen and carbon.
• Dextrose (Glucose): Fermentable carbohydrate energy source.
• Agar: Solidifying agent (typical concentration: 2%).

Common Applications:

• Yeast culture maintenance and propagation.
• Genetic transformation studies.
• Antimicrobial susceptibility testing for fungi.
• Fermentation research (e.g., ethanol production).

Preparation Protocol Highlights:

1. Dissolve 10g yeast extract, 20g peptone, and 20g dextrose in 1L distilled water.
2. Add 20g agar for solid medium.
3. Autoclave at 121°C for 15 minutes.
4. Pour plates at 45–50°C; store inverted at 4°C.

Critical Considerations:

• pH: Typically 6.5 (±0.2). Adjust with NaOH/HCl if needed.
• Contamination Risks: Avoid overheating dextrose to prevent caramelization.
• Alternatives: YPDA (YEPD + adenine) for adenine-auxotroph yeast strains.

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Microbiology Department

YEPD Agar MCQs Mock Test

Challenge your understanding of YEPD Agar—a cornerstone medium in yeast and fungal cultivation—with this 30-question MCQ mock test. Designed for lab technicians, researchers, and medical students, this test covers composition, applications, protocols, and troubleshooting. Assess your readiness for exams or lab work!

Understanding YEPD Agar

YEPD Agar (Yeast Extract Peptone Dextrose) is a nutrient-rich growth medium essential in microbiology for cultivating Saccharomyces cerevisiae, fungi, and recombinant yeast strains. Its simplicity and versatility make it indispensable in research, diagnostics, and industrial biotechnology.

Key Concepts to Review:

1. Composition:

   • Yeast Extract: Provides B vitamins and amino acids.

   • Peptone: Supplies nitrogen and peptides.

   • Dextrose (Glucose): Primary carbon/energy source.

   • Agar: Solidifying agent (typically 1.5–2%).

2. Applications:

   • Yeast transformation studies.

   • Fungal isolation and maintenance.

   • Fermentation research (e.g., ethanol production).

   • Antibiotic sensitivity testing in yeasts.

3. Preparation Protocol:

   • Dissolve 10 g yeast extract, 20 g peptone, and 20 g dextrose in 1L water.

   • Add 15–20 g agar, autoclave (121°C for 15 mins), and pour plates.

   • pH: Typically 6.5±0.2 (adjust with NaOH/HCl if needed).

4. Troubleshooting Tips:

   • Contamination? Check autoclave efficiency and sterile technique.

   • Poor growth? Verify dextrose concentration and storage conditions (store plates at 4°C).

5. Advantages Over Other Media:

   • Cost-effective vs. synthetic media (e.g., SC Agar).

   • Supports robust growth of non-fastidious yeasts.

Pro Tip: Use YEPD + antibiotics (e.g., G418) for selecting transformed yeast strains!

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Read Full Article: YEPD Agar FAQs and MCQs

1 / 30

Category: Clinical Laboratory

What happens if YEPD Agar is not autoclaved properly?

It solidifies too quickly

It loses all nutrients

It turns blue

It may remain contaminated

2 / 30

Category: Clinical Laboratory

Which component supplies B-complex vitamins in YEPD Agar?

Peptone

Yeast extract

Agar

Dextrose

3 / 30

Category: Clinical Laboratory

What does YEPD stand for?

Yeast Extract Protein Dextrose

Yeast Ethanol Peptone Dextrose

Yeast Extract Peptone Dextrose

Yeast Extract Phosphate Dextrose

4 / 30

Category: Clinical Laboratory

 Which yeast is likely to show luxuriant growth on YEPD Agar?

Kluyveromyces lactis

Aspergillus niger

Bacillus subtilis

Escherichia coli

5 / 30

Category: Clinical Laboratory

What is the final pH of YEPD Agar?

6.5 ± 0.2

5.0 ± 0.2

7.5 ± 0.2

7.0 ± 0.2

6 / 30

Category: Clinical Laboratory

Which phase of yeast growth is supported best by YEPD Agar?

Lag phase

Stationary phase

Exponential (log) phase

Death phase

7 / 30

Category: Clinical Laboratory

Which organism would NOT grow on YEPD Agar?

Escherichia coli

Kluyveromyces lactis

Saccharomyces cerevisiae

Candida albicans

8 / 30

Category: Clinical Laboratory

Which vitamin is supplied by yeast extract in YEPD Agar?

Vitamin C

Vitamin K

Vitamin D

B-complex vitamins

9 / 30

Category: Clinical Laboratory

Why is YEPD Agar preferred for yeast culture?

It changes color with yeast metabolism

It is selective against bacteria

It only allows mutant yeast growth

It supports fast yeast growth

10 / 30

Category: Clinical Laboratory

How should YEPD Agar plates be stored?

At 2-8°C

At room temperature

At -20°C

Under direct sunlight

11 / 30

Category: Clinical Laboratory

Which of the following is a correct application of YEPD Agar?

Antibiotic susceptibility testing

Yeast transformation

Viral culture

Bacterial sporulation

12 / 30

Category: Clinical Laboratory

Which of the following is NOT a component of YEPD Agar?

Dextrose

Sodium chloride

Yeast extract

Peptone

13 / 30

Category: Clinical Laboratory

At what temperature should YEPD Agar be autoclaved?

121°C for 15 minutes

130°C for 5 minutes

100°C for 10 minutes

115°C for 20 minutes

14 / 30

Category: Clinical Laboratory

YEPD Agar CANNOT be used for:

Routine yeast propagation

Growing Saccharomyces cerevisiae

Cultivating Candida albicans

Selecting yeast auxotrophs

15 / 30

Category: Clinical Laboratory

What is the purpose of boiling YEPD Agar during preparation?

To change its color

To dissolve the powder completely

To sterilize it

To reduce its pH

16 / 30

Category: Clinical Laboratory

What is the alternative to YEPD for auxotroph studies?

MacConkey Agar

LB Agar

Synthetic Dextrose (SD) Agar

Blood Agar

17 / 30

Category: Clinical Laboratory

How many grams of YEPD powder are needed per liter?

20 g

100 g

50 g

65 g

18 / 30

Category: Clinical Laboratory

What is the agar concentration in YEPD Agar?

5 g/L

10 g/L

20 g/L

15 g/L

19 / 30

Category: Clinical Laboratory

What is the solidifying agent in YEPD Agar?

Gelatin

tarch

Carrageenan

Agar

20 / 30

Category: Clinical Laboratory

Which component provides amino acids in YEPD Agar?

Agar

Dextrose

Yeast extract

Peptone

21 / 30

Category: Clinical Laboratory

Which of the following yeasts grows luxuriantly on YEPD Agar?

Pseudomonas aeruginosa

Staphylococcus aureus

Escherichia coli

Saccharomyces cerevisiae

22 / 30

Category: Clinical Laboratory

Which of the following is a chemoorganotroph?

Nitrosomonas

Purple sulfur bacteria

Yeast

Cyanobacteria

23 / 30

Category: Clinical Laboratory

YEPD Agar is a:

Differential medium

Minimal medium

Selective medium

Complete medium

24 / 30

Category: Clinical Laboratory

Why is YEPD Agar unsuitable for auxotroph selection?

It contains all required nutrients

It inhibits mutant strains

It is toxic to auxotrophs

It lacks essential amino acids

25 / 30

Category: Clinical Laboratory

What is the role of peptone in YEPD Agar?

Nitrogen source

pH indicator

Solidifying agent

Carbon source

26 / 30

Category: Clinical Laboratory

What is the primary carbon source in YEPD Agar?

Agar

Peptone

Dextrose

Yeast extract

27 / 30

Category: Clinical Laboratory

What type of medium is YEPD Agar?

Nutrient-rich complex medium

Selective and differential medium

Chemically defined medium

Synthetic minimal medium

28 / 30

Category: Clinical Laboratory

What is the function of dextrose in YEPD Agar?

Solidifying agent

Nitrogen source

pH buffer

Carbon and energy source

29 / 30

Category: Clinical Laboratory

What is the main limitation of YEPD Agar?

It is non-selective

It inhibits fungal growth

It requires anaerobic conditions

It is too expensive

30 / 30

Category: Clinical Laboratory

Which of the following is a limitation of YEPD Agar?

It cannot differentiate yeast species

It is toxic to Saccharomyces cerevisiae

It cannot grow wild-type yeasts

It requires UV light for growth

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Key Takeaways & Resources

Review Your Performance:

• Score 25+: Strong grasp of YEPD principles. Focus next on advanced applications (e.g., gene editing in yeast).
• Score 15–24: Solid foundation. Revise preparation protocols and contamination control.
• Score <15: Revisit core concepts below.

Must-Know Concepts Reinforced:

• Selectivity: YEPD is non-selective—supports broad yeast/fungal growth. For selectivity, additives like antibiotics (e.g., G418) are used.
• Troubleshooting:
  • Crystallization? → Re-autoclave agar separately.
  • Poor growth? → Verify dextrose integrity (avoid moisture degradation).
• Industrial Relevance: Used in biofuel production and recombinant protein synthesis (e.g., insulin).

Possible References Used

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