Free Bacteriology MCQs with Answers
167 Bacteriology MCQs from Microbiology, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
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167 questions · page 8 of 9
141. Granules in the corynebacterium diphtheria are called by following names, except______________?
- A. Metachromatic granules
- B. Refractile granules
- C. Babes Ernst granules
- D. Voluntin granules
Explanation: Corynebacterial inclusions are called metachromatic, Babes-Ernst or volutin granules.
Correct answer: Refractile granules142. Which of the following have the capability to produce extra cellular polysaccharides______________?
- A. Strep. Mutans
- B. Strep. pyogenes
- C. Peptostreptococcus
- D. Enterococcus
Explanation: Streptococcus mutans uses dietary sucrose to produce extracellular glucans and other polysaccharides, helping it adhere to teeth and form…
Correct answer: Strep. Mutans- A. Mannitol fermentation
- B. Hemolysis of sheep erythrocytes
- C. Detection of coagulase
- D. The catalase test
Explanation: Coagulase converts fibrinogen to fibrin and helps Staphylococcus aureus form a protective clot, making coagulase the key laboratory marker…
Correct answer: Detection of coagulase- A. Feaces
- B. Blood
- C. Urine
- D. All of the above
Explanation: Salmonella Typhi may be recovered from blood early in illness, from faeces later, and from urine in some cases.
Correct answer: All of the above- A. 2 degree
- B. 0 degree
- C. 27 degrees
- D. 37 degrees
Explanation: Most medically important Mycobacterium species, including M. tuberculosis, are cultivated at about 37°C because this matches the human…
Correct answer: 37 degrees- A. Bacterial flagella
- B. Spirochetes
- C. Both of the above
- D. None of the above
Explanation: Silver impregnation techniques can increase the visibility of very thin structures such as spirochetes and bacterial flagella.
Correct answer: Both of the above- A. Blue color
- B. Red color
- C. Green
- D. Colorless
Explanation: Gram-negative bacteria lose the crystal violet-iodine complex during alcohol decolourisation because their thin peptidoglycan layer cannot…
Correct answer: Red color- A. Spleen
- B. Gall Bladder
- C. Liver
- D. Salivary gland
Explanation: The gallbladder is the major reservoir in chronic typhoid carriers, where Salmonella Typhi can persist, especially in association with…
Correct answer: Gall Bladder- A. Beta phage
- B. Alfa phage
- C. Lambda K12
- D. Delta Phage
Explanation: Corynebacterium diphtheriae becomes toxigenic after lysogenic infection with a beta phage carrying the diphtheria toxin gene.
Correct answer: Beta phage- A. Mycobacterium bacilli
- B. Treponema pallidum
- C. Neisseria gonorrhea
- D. All of the above
Explanation: Mycobacteria have lipid-rich, mycolic-acid-containing cell walls that resist ordinary decolourisation with acid, so they are called…
Correct answer: Mycobacterium bacilli151. Group A B-hemolytic streptococcal infection of the pharynx may be followed in some by_____________?
- A. Diphtheria
- B. Typhoid fever
- C. Rheumatic fever
- D. Syphilis
Explanation: Group A beta-haemolytic Streptococcus pyogenes pharyngitis can trigger rheumatic fever through an immune cross-reaction several weeks…
Correct answer: Rheumatic fever- A. Borrelia vincenti and fusobacterium fusiformis
- B. Borrelia recurrents and bateroides
- C. Borrelia burgoloferi and lactobacillus
- D. Leptospira and Treponema pallidum
Explanation: Vincent's angina, or acute necrotising ulcerative gingivitis, is a fusospirochetal infection caused by Borrelia vincentii and…
Correct answer: Borrelia vincenti and fusobacterium fusiformis- A. with a cell wall but free of a capsule
- B. containing a cell wall and a capsule
- C. Free of a cell wall and a capsule
- D. Uniquely sensitive to penicillin
Explanation: A protoplast is a bacterial cell from which the cell wall has been completely removed, as in many Gram-positive bacteria; the capsule is…
Correct answer: Free of a cell wall and a capsule- A. Widal test
- B. Eleks test
- C. Mantoux test
- D. Wasserman test
Explanation: The Widal test is an agglutination test that detects antibodies against the O and H antigens of Salmonella Typhi.
Correct answer: Widal test- A. Pairs
- B. Chains
- C. Tetrads
- D. Irregular clusters
Explanation: Staphylococci divide in several planes and therefore characteristically form irregular, grape-like clusters.
Correct answer: Irregular clusters156. In a patient with typhoid, diagnosis after 15 days of onset of fever is best done by_____________?
- A. Blood culture
- B. Widal test
- C. Stool culture
- D. Urine culture
Explanation: Around the second week of typhoid fever, antibody titres are usually detectable, making the Widal test a commonly taught diagnostic…
Correct answer: Widal test- A. Outer membrane proteins
- B. IgA Protease
- C. M-Proteins
- D. Pili
Explanation: Neisseria gonorrhoeae uses pili, outer-membrane proteins and IgA protease for adherence, immune evasion and invasion.
Correct answer: M-Proteins- A. Conjugation
- B. Rarefaction
- C. Transduction
- D. Transformation
Explanation: Conjugation transfers resistance plasmids, especially R plasmids, directly between living bacteria and commonly spreads multidrug…
Correct answer: Conjugation- A. FTAB
- B. Widal test
- C. Wasserman test
- D. Kahn test
Explanation: The FTA-ABS test, written here as FTAB, is a treponemal test that detects antibodies specific to Treponema pallidum.
Correct answer: FTAB- A. Fimbria
- B. Flagella
- C. Capsule
- D. Cell wall
Explanation: Flagella are long, whip-like bacterial structures that rotate and propel the cell through liquid.
Correct answer: Flagella