Microbiology Study Questions #2

2.

Organisms that have become established in an area of the human body are referred to as:

Normal flora
Opportunists
Symbiotic
Pathogens

Correct Answer

A. Normal flora

Explanation

Normal flora refers to the microorganisms that naturally reside in or on the human body without causing harm. These organisms have established a balanced and mutually beneficial relationship with the human host. They help in various physiological processes, such as digestion, vitamin synthesis, and immune system regulation. Normal flora can be found in different areas of the body, such as the skin, mouth, intestines, and reproductive organs. Unlike pathogens, they do not cause disease unless there is an imbalance or disruption in their normal population.

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3.

The study of the factors that determine the occurrence of disease in populations is called:

Morbidity
Public health
Epidemiology
Infection control

Correct Answer

A. Epidemiology

Explanation

Epidemiology is the study of the factors that determine the occurrence of disease in populations. It involves investigating patterns, causes, and effects of diseases in order to prevent and control them. This field focuses on understanding how diseases spread, identifying risk factors, and developing strategies to reduce the impact of diseases on public health.

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4.

An opportunistic organism is a:

Harmless organism
Normal flora organism
Helpful organism
Potentially harmful organism

Correct Answer

A. Potentially harmful organism

Explanation

An opportunistic organism is a potentially harmful organism because it takes advantage of a weakened immune system or a specific opportunity to cause infection or disease. While it may not cause harm in a healthy individual, it can become dangerous when the conditions are favorable for its growth and proliferation. These organisms can cause infections like pneumonia, urinary tract infections, or bloodstream infections in individuals with compromised immune systems or underlying health conditions.

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5.

The first man to use an antiseptic in surgery to prevent infection was:

Lister
Koch
Pasteur
Tyndal

Correct Answer

A. Lister

Explanation

Lister is credited as the first man to use an antiseptic in surgery to prevent infection. He introduced the use of carbolic acid as a disinfectant during surgical procedures, which significantly reduced the occurrence of infections. Lister's pioneering work in antiseptic surgery revolutionized the field and laid the foundation for modern surgical practices. Koch, Pasteur, and Tyndal made significant contributions to the field of microbiology, but they were not specifically known for their use of antiseptics in surgery.

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6.

Certain dyes may be added to culture media to:

Indicate metabolic activity of microorganisms
Selectively grow certain microogranisms by inhibiting the growth of others
Both
Neither

Correct Answer

A. Both

Explanation

Certain dyes may be added to culture media to both indicate the metabolic activity of microorganisms and selectively grow certain microorganisms by inhibiting the growth of others. The dyes can act as indicators of metabolic activity by changing color in the presence of certain metabolic byproducts. Additionally, some dyes can have antimicrobial properties, allowing them to inhibit the growth of certain microorganisms while promoting the growth of others. Therefore, the addition of dyes to culture media can serve both purposes simultaneously.

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7.

The most powerful method of sterilization by heat is:

Dry heat
Boiling
Live steam
Steam under pressure

Correct Answer

A. Steam under pressure

Explanation

Steam under pressure is the most powerful method of sterilization by heat because it allows for higher temperatures to be reached, which is essential for killing all types of microorganisms, including spores. The high pressure helps to increase the temperature of the steam, ensuring effective sterilization. This method is commonly used in autoclaves, where items are exposed to steam under pressure for a specific period of time to achieve complete sterilization. Dry heat, boiling, and live steam are also used for sterilization, but they are not as powerful or effective as steam under pressure.

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8.

Virulence is:

Infectiveness
Pathogenicity
Degree of pathogenicity
Invasiveness

Correct Answer

A. Degree of pathogenicity

Explanation

Virulence refers to the degree or extent to which a pathogen can cause disease or harm to its host. It is a measure of the pathogenicity of a microorganism, indicating how severe or harmful the infection can be. The term "virulence" encompasses factors such as the ability of the pathogen to invade host tissues, damage cells, evade the immune system, and produce toxins. Therefore, the correct answer for this question is "degree of pathogenicity," as it accurately describes the concept of virulence.

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9.

One of the following is a selective medium used to isolate pathogenic gram negative bacilli from stool specimen:

Salmonella-shigella
Sheep blood agar
MacConkey
Eosin-methylene blue

Correct Answer

A. Salmonella-shigella

Explanation

Salmonella-shigella is a selective medium used to isolate pathogenic gram-negative bacilli from stool specimens. This medium contains inhibitors that suppress the growth of normal flora and allow the growth of Salmonella and Shigella species. These bacteria are known to cause gastrointestinal infections and are commonly found in contaminated food or water. By using Salmonella-shigella agar, the presence of these pathogenic bacteria can be detected and isolated for further identification and testing.

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10.

The best choice to disinfect a nonmetallic surfaces contaminated with blood would be:

A phenol solution
Fresh 5% bleach
70% isopropyl alcohol
Green soap

Correct Answer

A. Fresh 5% bleach

Explanation

Fresh 5% bleach is the best choice to disinfect nonmetallic surfaces contaminated with blood. Bleach is a powerful disinfectant that can effectively kill a wide range of microorganisms, including bacteria and viruses. The 5% concentration is strong enough to be effective but not too strong to cause damage to the surface being disinfected. Additionally, using fresh bleach ensures that the disinfectant is at its maximum potency, as bleach loses its effectiveness over time.

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Microbiology Study Questions #2

Organisms which grow in the presence of atmospheric oxygen are:

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Organisms that have become established in an area of the human body are referred to as:

The study of the factors that determine the occurrence of disease in populations is called:

An opportunistic organism is a:

The first man to use an antiseptic in surgery to prevent infection was:

Certain dyes may be added to culture media to:

The most powerful method of sterilization by heat is:

Virulence is:

One of the following is a selective medium used to isolate pathogenic gram negative bacilli from stool specimen:

The best choice to disinfect a nonmetallic surfaces contaminated with blood would be: