Microbiology Multiple Choice Questions on “World of Bacteria I – Aerobic Gram – Negative Rods and Cocci”.
1. Pseudomonas bacteria uses which of the following as an electron acceptor for anaerobic respiration?
A. Oxygen
B. Nitrate
C. Phosphate
D. Sulphate
Answer: B
Clarification: All pseudomonads can grow aerobically, but some can also grow anaerobically by using nitrate as an electron acceptor.
2. Pseudomonas maltophilia is a fluorescent species.
A. True
B. Flase
Answer: B
Clarification: Pseudomonas maltophilia is a non-fluorescent species that is also frequently isolated from clinical specimens.
3. Pyocyanin, a blue water-soluble pigment is produced by which of the following pseudomonads?
A. P.mallei
B. P.syringae
C. P.fluorescens
D. P.aeruginosa
Answer: D
Clarification: Pseudomonas aeruginosa produces a water-soluble blue pigment, pyocyanin. The organism is mainly a soil and water saprophyte but can also be isolated from wound, burn etc.
4. Which of the following are important plant pathogens?
A. P. aeruginosa
B. P.maltophilia
C. P.syringae
D. P.pseudomallei
Answer: C
Clarification: P. syringae are important plant pathogens, causing diseases such as leaf spot, leaf stripe, wilt, and necrosis.
5. What is the color of the pigment xanthomonadin?
A. Blue
B. Yellow
C. Fluorescent
D. Red
Answer: B
Clarification: Xanthomonadin is a yellow pigment formed by bacteria of the genus Xanthomonas of the family Pseudomonadaceae.
6. Which of the following is an important characteristic of bacteria belonging to Zoogloea?
A. They are plant pathogens
B. Cells are embedded in a gelatinous matrix
C. Cause diseases in humans
D. Useful for industrial applications
Answer: B
Clarification: The outstanding characteristic of the genus Zoogloea is the embedment of cells in a gelatinous matrix to form slimy masses with a fingerlike morphology. They are mainly used in the sewage treatment plant.
7. Which of the following family of bacteria fix nitrogen under aerobic conditions?
A. Pseudomonadaceae
B. Azotobacteraceae
C. Rhizobiaceae
D. Methylcoccaceae
Answer: B
Clarification: The family Azotobacteraceae have organisms that can fix nitrogen under aerobic conditions.
8. Agrobacterium also fixes atmospheric nitrogen.
A. True
B. False
Answer: B
Clarification: Agrobacteria do not fix atmospheric nitrogen. The organisms are plant pathogens that incite tumors when they invade roots, crown and stems.
9. Methylococcus and Methylomonas are all _______________ methane-oxidizers.
A. aerobic
B. facultative
C. obligate
D. anaerobic
Answer: C
Clarification: Methylococcus and Methylomonas are all obligate methane-oxidizers i.e., carbon-sources such as glucose cannot be used for growth.
10. Which of the following have peritrichous flagella?
A. Acetobacter
B. Gluconobacter
C. Agrobacteria
D. Rhizobium
Answer: A
Clarification: Acetobacter possesses peritrichous flagella. They belong to the family Acetobacteraceae.
11. Bacteria belonging to the genus Legionella contains which of the following amino acid?
A. Lysine
B. Arginine
C. Glycine
D. Cysteine
Answer: D
Clarification: Bacteria belonging to genus Legionella are rod-shaped bacteria that require L-cysteine, iron saltsand activated powdered charcoal for growth.
12. Which of the following organism causes whooping cough in humans?
A. E.coli
B. Bordetella pertussis
C. Francisella tularensis
D. F.meningosepticum
Answer: B
Clarification: Bordetella pertussis occurs only in humans and causes whooping cough. They are parasitic and pathogenic for various mammalian hosts.
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