MDS PREP
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.
Which of the following statements about the fermentation of sugars by Anthracoid bacilli is true?
1) Anthracoid bacilli ferment glucose, maltose, lactose, and sucrose, producing acid and gas.
2) Anthracoid bacilli do not ferment glucose but ferment maltose, lactose, and sucrose.
3) Anthracoid bacilli only ferment glucose.
4) Anthracoid bacilli ferment glucose, maltose, and lactose, but not sucrose.
Anthracoid bacilli ferment glucose, maltose, lactose, and sucrose, producing acid and gas.
What is a characteristic feature of Streptococcus viridans?
1) Capsulated, oval-shaped cells
2) Non-capsulated, round to oval cells in chains
3) Positive oxidase reaction
4) Negative oxidase reaction
Streptococcus viridans is characterized by non-capsulated, round to oval cells in chains and has a negative oxidase reaction.
On a medium containing 6% agar, 5% Fildes peptic digest of sheep blood, and 20% human serum, which of the following is NOT a typical characteristic of C1. Perfringens colonies?
1) They will be surrounded by a zone of opacity on the half without antitoxin due to the Nagler reaction
2) They are nonmotile
3) They are capsulated
4) They ferment lactose and produce bright pink colonies on MacConkey’s medium
General Microbiology Answer: 2
C1. Perfringens colonies are typically nonmotile and do not form capsules. They will be surrounded by a zone of opacity on the half without antitoxin due to the Nagler reaction (option 1) and will not ferment lactose to produce bright pink colonies on MacConkey’s medium
The destruction of microorganisms on living tissues, as long as there is contact between the tissues and the antimicrobial agent, denotes
1. sterilization
2. antisepsis
3. sanitization
4. none of the above
Microbiology
Answer: 2
The destruction of microorganisms on living tissues, as long as there is contact between the tissues and the antimicrobial agent, denotes antisepsis (option 2). Antisepsis refers to the application of antimicrobial agents to living tissues to reduce the possibility of infection, sepsis, or putrefaction.
Sterilization:
This is the process of completely eliminating all forms of microbial
life, including bacteria, viruses, fungi, and spores, from an object or
surface. Sterilization is typically achieved through methods such as
autoclaving (steam under pressure), dry heat, chemical sterilants, or
radiation. Sterilization is used for medical instruments, laboratory
equipment, and other items that must be free of all microorganisms.
Antisepsis:
Antisepsis refers to the application of antimicrobial agents to
living tissues to reduce the risk of infection, sepsis, or putrefaction.
Antiseptics are used on skin and mucous membranes to prevent infection
during surgical procedures, wound care, and other medical interventions.
Common antiseptics include alcohol, iodine solutions, and chlorhexidine.
Sanitization:
Sanitization is the process of reducing the number of microorganisms
on surfaces or objects to a level considered safe by public health
standards. This does not necessarily eliminate all microorganisms but
reduces them to a level that minimizes the risk of infection or disease.
Sanitization is commonly used in food service, public restrooms, and
other environments where hygiene is important.
What type of genome do Hepatitis B viruses have?
1) ssRNA
2) dsDNA
3) ssDNA
4) dsRNA
General Microbiology Answer: 2Hepatitis B viruses possess a double-stranded DNA (dsDNA) genome, which is unique among the hepatitis viruses. This dsDNA is partially double-stranded and circular, playing a crucial role in the virus life cycle and replication.
In concentrations usually applied for sterilization purposes, ethylene oxide is preferable to formaldehyde becuase it is
1. more readily polymerized to an active form
2. less toxic
3. less likely to form an explosive mixture with air
4. more penetrating
Microbiology
Answer: 4
In concentrations usually applied for sterilization purposes, ethylene oxide is preferable to formaldehyde becuase it is more penetrating
Which of the following is a distinguishing feature of orthomyxoviruses?
1) Single linear RNA
2) 80-120 nm in size
3) Hemolysin present
4) Cytoplasmic replication
General Microbiology Answer: 2Orthomyxoviruses, which include the influenza viruses, are characterized by their single-stranded RNA genome. This feature distinguishes them from other virus families that may have different types of genetic material. Orthomyxoviruses are distinguished by their single linear RNA genome, which is essential for their replication and pathogenicity.