Nokea
The complex of all biological processes/mechanisms is responsible for the state of steady internal, physical, chemical conditions in the living systems and defense against all foreign agents is known as:
- A. Infection
- B. Commensalism
- C. Immunity
- D. Homeostasis
Correct Answer: C
Rationale: Rationale for Correct Answer (C - Immunity):
1. Immunity refers to the body's ability to defend against foreign agents.
2. Homeostasis is the state of steady internal conditions, not specifically related to defense.
3. Infection is the invasion and multiplication of pathogens, not the overall defense mechanism.
4. Commensalism is a symbiotic relationship where one organism benefits without harming the other.
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What is the name of the enzyme that allows the bacteria to become resistant to most penicillins?
- A. Beta lactam ring
- B. MRSA
- C. Beta lactamase
- D. Aminoglycoside ring
Correct Answer: C
Rationale: The correct answer is C: Beta lactamase. This enzyme is produced by bacteria to break down the beta-lactam ring structure of penicillins, rendering them ineffective. Beta lactam ring (A) is part of the penicillin molecule, not an enzyme. MRSA (B) stands for methicillin-resistant Staphylococcus aureus, a type of bacteria resistant to certain antibiotics, not an enzyme. Aminoglycoside ring (D) refers to a different class of antibiotics and is not related to penicillin resistance in bacteria.
Study of bacteriological sputum specimens stained by the Ziel-Neelsen method revealed some bright-red acid-resistant bacilli that were found in groups or singularly. When inoculated onto the nutrient media, the signs of their growth show up on the 10-15 day. These bacteria relate to the following family:
- A. Micobacterium tuberculosis
- B. Yersinia pseudotuberculosis
- C. Histoplasma dubrosii
- D. Klebsiella rhinoscleromatis
Correct Answer: A
Rationale: The correct answer is A: Mycobacterium tuberculosis.
1. Bright-red acid-resistant bacilli indicate the presence of mycolic acids in the cell wall, characteristic of Mycobacterium species.
2. Found in groups or singularly suggests the clumping nature of acid-fast bacilli.
3. Growth appearing after 10-15 days on nutrient media is consistent with the slow growth rate of Mycobacterium tuberculosis.
4. Yersinia pseudotuberculosis (B) and Klebsiella rhinoscleromatis (D) are not acid-fast bacilli and do not match the growth characteristics described.
5. Histoplasma dubrosii (C) is a fungus, not a bacterium, and does not exhibit acid-fast staining or the described growth pattern.
Antibodies against influenza viruses in a patient's serum can be determined by;
- A. Agglutination reaction
- B. Precipitation reaction in agar gel
- C. Reaction haemagglutination inhibition
- D. Ration haemagglutination
Correct Answer: C
Rationale: The correct answer is C: Reaction haemagglutination inhibition. This method is used to detect antibodies against influenza viruses by measuring the ability of the patient's serum to inhibit haemagglutination. This is a specific and sensitive technique for detecting influenza antibodies.
A: Agglutination reaction is not specific for influenza viruses and may give false positives.
B: Precipitation reaction in agar gel is not typically used for detecting influenza antibodies.
D: Ration haemagglutination is not a standard method for detecting influenza antibodies.
The role of pili in bacteria is:
- A. protection from desiccation
- B. motility
- C. adhesion to surfaces and conjugation
- D. spore formation
Correct Answer: C
Rationale: The correct answer is C: adhesion to surfaces and conjugation. Pili are hair-like structures on the surface of bacteria that help them adhere to surfaces and facilitate the transfer of genetic material during conjugation. This is essential for bacterial survival and reproduction. Choice A is incorrect because protection from desiccation is typically associated with other structures like capsules. Choice B is incorrect as motility in bacteria is usually facilitated by flagella. Choice D is incorrect as spore formation involves the formation of specialized structures, not pili.
Infections of the CNS can be caused by:
- A. Clostridium botulinum
- B. Morbillivirus morbillorum
- C. Clostridium tetani
- D. All are correct
Correct Answer: D
Rationale: The correct answer is D because all three choices, Clostridium botulinum, Morbillivirus morbillorum, and Clostridium tetani, can cause infections of the CNS. Clostridium botulinum can lead to botulism, affecting the nervous system. Morbillivirus morbillorum can cause measles, which can lead to encephalitis. Clostridium tetani can cause tetanus, affecting the central nervous system. Therefore, all three choices can cause infections of the CNS. Choices A, B, and C are incorrect individually because each pathogen can cause CNS infections.