MDS PREP
Which of the following is a distinguishing feature of exotoxins?
1) Lipopolysaccharides
2) Heat stable
3) Actively secreted by cells
4) Obtained only by cell lysis
General Microbiology Answer: 3
Exotoxins are produced and secreted by bacteria into the surrounding environment. They are typically proteins that can cause damage to the host by disrupting cellular processes. This active secretion distinguishes them from endotoxins, which are part of the bacterial cell wall and are released upon cell lysis.
Which of the following is a characteristic of endotoxins that makes them distinct from exotoxins?
1) They are heat labile
2) They are actively secreted by bacterial cells
3) They are proteins
4) They are part of the bacterial cell wall
General Microbiology Answer: 4
Endotoxins are components of the outer membrane of Gram-negative bacteria and are released when the bacteria die or divide. This structural characteristic differentiates them from exotoxins, which are secreted by living bacteria.
What is the purpose of the puncture-proof container in bio-medical waste management?
1) To contain sharps
2) To hold non-infectious waste
3) To store chemicals used for disinfection
4) To transport pathological waste
General Microbiology Answer: 1
The purpose of the puncture-proof container in bio-medical waste management is to contain sharps, preventing injuries and contamination.
Which of the following is NOT a type of C1. Perfringens that can cause food poisoning?
1) C1. Perfringens type A
2) C1. Perfringens type B
3) C1. Perfringens type C
4) C1. Perfringens type D
General Microbiology Answer: 4
C1. Perfringens types A, B, and C are capable of producing toxins that cause food poisoning. Type D, however, is not associated with foodborne illness. It is primarily involved in diseases such as gas gangrene and other infections due to the production of different types of toxins.
Which of the following is NOT a direct method for diagnosing tuberculosis?
1) Smear examination
2) ELISA
3) Culture methods
4) Nucleic acid technology
General Microbiology Answer: 2ELISA: While ELISA (Enzyme-Linked Immunosorbent Assay) can be used to detect antibodies to the tuberculosis bacterium, it is not a direct method for diagnosing active TB infection. Direct methods include smear examination, culture, and nucleic acid technology, which detect the actual presence of the bacteria in the patient sample.
What does one unit of antitoxin refer to in the context of diphtheria toxin?
1) The amount needed to neutralize 100 MLD of toxin
2) The amount of antitoxin that causes the toxin to flocculate
3) The amount that confers immunity to an individual
4) The amount of toxin that can cause disease in an average host
One unit of antitoxin refers to the amount needed to neutralize 100 MLD of diphtheria toxin.
What is the diameter of prions?
1) 2-4 nm
2) 4-6 nm
3) 10-12 nm
4) 20-25 nm
General Microbiology Answer: 2Prions are extremely small infectious agents, typically measuring between 4 to 6 nanometers in diameter. Their small size contributes to their ability to evade the immune system and resist conventional sterilization methods.
What is the primary mode of action of exotoxins?
1) Enzymatic
2) Non-enzymatic
3) Structural disruption
4) Inhibition of protein synthesis
General Microbiology Answer: 1
The primary mode of action of exotoxins is enzymatic, as they often act as enzymes that modify or damage host cell functions.