Yeasts Practice Questions
20 free Yeasts practice questions for the Microbiology. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.
What are yeasts?
- A Unicellular fungi
- B Multicellular fungi
- C Filamentous molds
- D Dimorphic fungi
Correct answer: Unicellular fungi
Yeasts are unicellular fungi that reproduce mainly by budding. They differ from molds, which are multicellular.
Which yeast is commonly used in baking?
- A Saccharomyces cerevisiae
- B Candida albicans
- C Schizosaccharomyces pombe
- D Candida tropicalis
Correct answer: Saccharomyces cerevisiae
Saccharomyces cerevisiae is widely used in baking and brewing. It ferments sugars to produce carbon dioxide and ethanol.
What is the main mode of reproduction in yeasts?
- A Budding
- B Fission
- C Spore formation
- D Fragmentation
Correct answer: Budding
Yeasts primarily reproduce by budding, where a new cell forms as an outgrowth of the parent cell. It eventually detaches.
Which yeast is commonly associated with human infections?
- A Saccharomyces cerevisiae
- B Candida albicans
- C Rhizopus
- D Aspergillus
Correct answer: Candida albicans
Candida albicans is an opportunistic yeast that can cause infections such as thrush. It commonly affects immunocompromised individuals.
What type of organism is Candida albicans?
- A Bacterium
- B Virus
- C Yeast
- D Protozoa
Correct answer: Yeast
Candida albicans is a yeast and part of normal human flora. Under certain conditions, it can become pathogenic.
Which structure is formed by some yeasts resembling hyphae?
- A True hyphae
- B Pseudohyphae
- C Conidiospores
- D Septa
Correct answer: Pseudohyphae
Pseudohyphae are elongated yeast cells that remain attached after budding. They resemble hyphae but are not true hyphae.
Which environmental condition favors yeast growth?
- A Extremely arid conditions
- B Moist, nutrient-rich area
- C Intense radiation exposure
- D Low-nutrient environment
Correct answer: Moist, nutrient-rich area
Yeasts grow best in moist, nutrient-rich environments with available sugars. These conditions support fermentation and reproduction.
What is fermentation in yeasts?
- A Oxidative breakdown of glucose using oxygen
- B Conversion of sugars into alcohol and CO2
- C Duplication of DNA during cell division
- D Synthesis of structural proteins in cells
Correct answer: Conversion of sugars into alcohol and CO2
Yeasts ferment sugars anaerobically to produce ethanol and carbon dioxide. This process is used in baking and brewing.
Which disease is caused by yeast infection in the mouth?
- A Tuberculosis
- B Thrush
- C Malaria
- D Typhus
Correct answer: Thrush
Thrush is a fungal infection caused by Candida species. It appears as white patches in the mouth.
Which type of metabolism do yeasts use in absence of oxygen?
- A Photosynthesis
- B Fermentation
- C Respiration
- D Nitrogen fixation
Correct answer: Fermentation
In anaerobic conditions, yeasts switch to fermentation. This allows them to generate energy without oxygen.
What is the shape of most yeast cells?
- A Rod-shaped
- B Spiral-shaped
- C Oval or spherical
- D Filamentous and branching
Correct answer: Oval or spherical
Yeasts typically have oval or spherical shapes. This distinguishes them from filamentous fungi.
Which component is present in yeast cell walls?
- A Peptidoglycan
- B Lignin
- C Lipid layer
- D Chitin
Correct answer: Chitin
Yeast cell walls contain chitin and glucans. These components provide structural support and protection.
Which yeast can switch between yeast and filamentous forms?
- A Saccharomyces cerevisiae
- B Rhizopus
- C Penicillium
- D Candida albicans
Correct answer: Candida albicans
Candida albicans is dimorphic and can switch between yeast and filamentous forms. This ability contributes to its pathogenicity.
Which test is commonly used to identify Candida albicans?
- A Gram staining
- B PCR amplification
- C Western blot
- D Germ tube test
Correct answer: Germ tube test
The germ tube test is used to identify Candida albicans. It detects the formation of germ tubes in serum.
Which industrial product is made using yeast fermentation?
- A Antibiotics
- B Vaccines
- C Dyes
- D Bread
Correct answer: Bread
Yeast fermentation produces carbon dioxide, which helps bread rise. It is widely used in baking industries.
Which yeast infection affects the genital area?
- A Thrush
- B Malaria
- C Tuberculosis
- D Candidiasis
Correct answer: Candidiasis
Candidiasis is a yeast infection affecting mucosal areas, including the genital region. It is often caused by Candida albicans.
Which condition increases the risk of yeast infections?
- A Strong immune system
- B Healthy diet
- C Exercise
- D Antibiotic use
Correct answer: Antibiotic use
Antibiotics can disrupt normal flora, allowing yeast overgrowth. This increases the risk of infections like candidiasis.
Which yeast is used in alcohol production?
- A Candida albicans
- B Aspergillus brasiliensis
- C Saccharomyces cerevisiae
- D Rhizopus
Correct answer: Saccharomyces cerevisiae
Saccharomyces cerevisiae ferments sugars into ethanol. It is used in brewing and wine-making industries.
What is a budding scar in yeast?
- A Mark left after budding
- B Infection site
- C Spore structure
- D Inherited cell wall defect
Correct answer: Mark left after budding
A budding scar is a mark left on the parent cell after a daughter cell separates. It indicates previous budding events.
Which antifungal drug is commonly used to treat yeast infections?
- A Fluconazole
- B Penicillin
- C Amoxicillin
- D Erythromycin
Correct answer: Fluconazole
Fluconazole is commonly used to treat fungal infections, including candidiasis. It inhibits fungal cell membrane synthesis.