Nokea
Saprophytes are microorganisms which:
- A. Can induce typical infection
- B. Cannot induce infectious disease
- C. Can induce chronic infection
- D. Can induce mixed infection
Correct Answer: B
Rationale: The correct answer is B: Cannot induce infectious disease. Saprophytes are microorganisms that obtain nutrients from decaying organic matter and do not cause infectious diseases in humans. They play a vital role in the ecosystem by decomposing dead organisms. Choice A is incorrect because saprophytes do not cause typical infections. Choice C is incorrect because saprophytes do not cause chronic infections. Choice D is incorrect because saprophytes do not cause mixed infections involving multiple pathogens. Therefore, the correct answer is B as saprophytes do not induce infectious diseases.
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Risk factor for the development of infection is
- A. malignant disease
- B. cytostatic therapy
- C. premature birth
- D. all of them
Correct Answer: D
Rationale: The correct answer is D: all of them. Malignant disease weakens the immune system, making individuals more susceptible to infections. Cytostatic therapy suppresses the immune system, increasing the risk of infections. Premature birth can lead to underdeveloped immune systems, making babies more prone to infections. Therefore, all three choices are risk factors for the development of infections. Other choices are incorrect because each individual risk factor listed contributes to an increased susceptibility to infections.
Which bacteria is known for causing tuberculosis?
- A. Mycobacterium tuberculosis
- B. Mycobacterium leprae
- C. Escherichia coli
- D. Streptococcus pneumoniae
Correct Answer: A
Rationale: The correct answer is A: Mycobacterium tuberculosis. This bacterium is known for causing tuberculosis, as it specifically infects the lungs and can lead to serious respiratory issues. Mycobacterium leprae (Choice B) causes leprosy, not tuberculosis. Escherichia coli (Choice C) is a common bacteria found in the intestines and is not associated with tuberculosis. Streptococcus pneumoniae (Choice D) causes pneumonia, but not tuberculosis. Therefore, the correct choice is A because Mycobacterium tuberculosis is the specific bacterium responsible for causing tuberculosis.
The process of bacterial conjugation involves:
- A. DNA transfer via bacteriophage
- B. Uptake of naked DNA from the environment
- C. Direct transfer of DNA between two bacterial cells
- D. Binary fission
Correct Answer: C
Rationale: The correct answer is C: Direct transfer of DNA between two bacterial cells. In bacterial conjugation, genetic material is transferred directly from one bacterial cell to another through a conjugative pilus. This process involves physical contact between the cells, followed by the transfer of plasmid DNA or chromosomal DNA. This mechanism allows for the exchange of genetic information between bacteria, leading to genetic diversity.
Explanation of why other choices are incorrect:
A: DNA transfer via bacteriophage - Bacteriophage is a virus that infects bacteria and transfers its genetic material, but this is not the mechanism involved in bacterial conjugation.
B: Uptake of naked DNA from the environment - This process is known as transformation, where bacteria take up free DNA from the environment, but it is not specific to bacterial conjugation.
D: Binary fission - Binary fission is a form of asexual reproduction in bacteria where a single cell divides into two identical cells, and it is not related to the process
The relations between the macroorganism and the resident skin microflora are defined as:
- A. Commensalism
- B. Infection
- C. Parasitism
- D. No correct answer
Correct Answer: A
Rationale: The correct answer is A: Commensalism. In this relationship, the skin microflora benefits from the host without causing harm or benefitting it. This is evident in the mutualistic interaction where the microflora receive nutrients and a place to live, while the host remains unaffected. Choice B, Infection, is incorrect because it implies harm to the host. Choice C, Parasitism, is also incorrect as it involves one organism benefiting at the expense of the other. Choice D, No correct answer, is not applicable here as Commensalism accurately describes the relationship between the macroorganism and skin microflora.
Which structure allows bacteria to survive in adverse conditions?
- A. Flagella
- B. Capsule
- C. Endospore
- D. Pili
Correct Answer: C
Rationale: The correct answer is C: Endospore. Endospores are dormant, tough, and non-reproductive structures formed by certain bacteria as a response to unfavorable conditions. They help bacteria survive harsh environments such as extreme temperatures, desiccation, and exposure to harmful chemicals. The other choices, Flagella (A), Capsule (B), and Pili (D), do not directly contribute to bacterial survival in adverse conditions. Flagella aid in bacterial movement, capsules provide protection from immune system attacks, and pili are involved in attachment to surfaces or other cells. Endospores are specifically designed for survival during unfavorable conditions, making them the correct choice in this scenario.