Which bacterial genus requires X factor (hemin) and V factor (NAD) for growth, making it fastidious?

The correct answer is B: Haemophilus. Haemophilus species are fastidious gram-negative coccobacilli requiring both X factor (hemin) and V factor (NAD). Culture on chocolate agar provides these factors; they won't grow on regular blood agar.

Which of the following bacterial genera includes species that form mycelia-like structures similar to fungi?

The correct answer is A: Actinobacteria (Streptomyces). Actinobacteria, particularly Streptomyces species, form branching hyphae and mycelial networks resembling fungi, though they are prokaryotes producing many clinically useful antibiotics.

A bacterial strain shows resistance to multiple antibiotics. Which genetic element is most likely responsible?

The correct answer is B: Plasmids carrying resistance genes. Plasmids are extra-chromosomal DNA elements that carry multiple antibiotic resistance genes and can be horizontally transferred between bacteria, leading to multi-drug resistance.

A patient presents with community-acquired pneumonia. Culture on MacConkey agar shows non-fermentative, oxidase-positive colonies. Which organism is most likely?

The correct answer is B: Pseudomonas aeruginosa. Pseudomonas aeruginosa is a non-fermentative, oxidase-positive, Gram-negative rod commonly associated with respiratory infections and shows characteristic green pigmentation.

Which virus possesses a segmented genome and is responsible for causing influenza pandemics?

The correct answer is A: Influenza A virus. Influenza A virus has 8 RNA segments, enabling antigenic reassortment. This segmentation allows rapid evolution and pandemic potential through genetic exchange with other influenza strains.

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Microbiology

Bacteria, viruses, immunology, genetics

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All Bacteria & Viruses 100

Q.31 Easy Bacteria & Viruses

Which of the following bacteria is gram-positive and forms spores?

A Bacillus subtilis

B Escherichia coli

C Vibrio cholerae

D Pseudomonas aeruginosa

Correct Answer: A. Bacillus subtilis

EXPLANATION

Bacillus subtilis is a gram-positive, rod-shaped bacterium capable of forming endospores. E. coli is gram-negative, V. cholerae is gram-negative curved rod, and P. aeruginosa is gram-negative.

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