A child exposed to cowpox develops immunity to smallpox. This demonstrates:
Vaccination
Antibiotic resistance
Sterilization
The Correct Answer is A
A. Vaccination: Vaccination involves the introduction of a harmless or weakened pathogen, or part of a pathogen, into the body to stimulate an immune response without causing the disease itself. In this example, exposure to cowpox, a virus similar to smallpox but much less virulent, trains the immune system to recognize and respond to smallpox, providing protective immunity. This principle forms the basis of immunization.
B. Antibiotic resistance: Antibiotic resistance occurs when bacteria evolve mechanisms to survive exposure to antibiotics that would normally kill them or inhibit their growth. It is unrelated to viral exposure or immune system training, and thus does not explain immunity following cowpox exposure.
C. Sterilization: Sterilization is the complete destruction of all microorganisms, including spores, on inanimate objects. It is a physical or chemical process used to prevent infection but does not confer immunity or involve the immune system. Therefore, sterilization does not explain the protective effect observed in the child exposed to cowpox.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
A. Pilus: During bacterial conjugation, a specialized structure called a sex pilus (or conjugation pilus) forms a direct connection between two bacterial cells. The donor cell transfers a copy of plasmid DNA or other genetic material through this pilus to the recipient cell, allowing for horizontal gene transfer and the spread of traits such as antibiotic resistance.
B. Capsule: The bacterial capsule is a polysaccharide layer that surrounds the cell wall and provides protection against phagocytosis and desiccation. It does not play a role in the transfer of DNA between bacterial cells, and therefore is not involved in conjugation.
C. Flagellum: The flagellum is a whip-like appendage that enables bacterial motility. While important for movement and chemotaxis, it is not used for DNA transfer during conjugation. DNA exchange occurs specifically through the pilus, not through flagella.
Correct Answer is D
Explanation
A. Halophile: Halophiles are organisms that thrive in high-salt environments. The description of temperature-based growth does not indicate a preference for saline conditions, so this term would not apply to the observed growth pattern.
B. Anaerobe: Anaerobes are organisms that grow in the absence of oxygen. The scenario focuses on temperature preferences, not oxygen requirements.
C. Mesophile: Mesophiles grow optimally at moderate temperatures, typically between 20°C and 45°C, with 37°C being ideal for many human-associated mesophilic bacteria. Because this species did not grow at 37°C or 50°C, it does not fit the definition of a mesophile.
D. Psychrophile: Psychrophiles are organisms that thrive at cold temperatures, usually with optimal growth at 0–15°C and survival at temperatures below 20°C. The abundant growth in the refrigerator and minimal growth at room temperature, with no growth at 37°C or higher, indicates that this species is adapted to cold environments, fitting a psychrophile definition.
E. Capnophile: Capnophiles require elevated levels of carbon dioxide for optimal growth. The growth pattern described is based on temperature rather than carbon dioxide levels, so this term is not applicable.
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