Nokea
Deficiencies in the classical pathway of complement are associated with:
- A. Increased cancer risk
- B. Resistance to bacterial infections
- C. Systemic lupus erythematosus (SLE)
- D. Overactivation of adaptive immunity
Correct Answer: C
Rationale: Rationale:
1. Deficiencies in the classical pathway lead to impaired clearance of immune complexes, hence contributing to SLE.
2. This pathway plays a crucial role in removing self-antigens and maintaining immune tolerance.
3. Increased cancer risk (A) is not directly linked to classical pathway deficiencies.
4. Resistance to bacterial infections (B) is more associated with deficiencies in the alternative pathway.
5. Overactivation of adaptive immunity (D) is not a direct consequence of classical pathway deficiencies.
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The way in which some organism supplies some other organism with food and energy known as
- A. Food chains
- B. Food Network
- C. Pyramid of power
- D. levels of nutrition
Correct Answer: A
Rationale: The correct answer is A: Food chains. A food chain depicts the flow of energy and nutrients from one organism to another in an ecosystem. It shows how energy is transferred from producers to consumers. Food network (B) is a more complex and interconnected system than a simple linear chain. Pyramid of power (C) represents the energy flow in an ecosystem, not the transfer of food. Levels of nutrition (D) is not a term commonly used to describe how organisms transfer food and energy.
Sacl restriction endonuclease reactions produce fragments with
- A. blunt end
- B. None of the options are correct
- C. 5' cohesive ends
- D. 3' cohesive ends
Correct Answer: C
Rationale: The correct answer is C: 5' cohesive ends. Sacl restriction endonuclease cuts DNA at specific recognition sites, leaving single-stranded overhangs called cohesive ends. In this case, Sacl creates 5' overhangs, resulting in fragments with 5' cohesive ends. Blunt ends (option A) have no overhangs, making them incorrect. Options B and D are incorrect as they do not align with the specific characteristic of Sacl restriction endonuclease's cleavage pattern.
Which of the following about Influenza virus is NOT correct
- A. It's an RNA virus
- B. In humans influenza infects the lung epithelial cells
- C. Release of newly formed virus from the infected cell is mediated by Hemagglutinin (HA)
- D. Tamiflu is a Neuraminidase (NA) inhibitor
Correct Answer: C
Rationale: The correct answer is C because the release of newly formed virus from the infected cell is actually mediated by Neuraminidase (NA), not Hemagglutinin (HA).
1. Influenza virus is indeed an RNA virus (Choice A).
2. In humans, influenza primarily infects lung epithelial cells (Choice B).
3. Hemagglutinin (HA) helps the virus enter host cells, while Neuraminidase (NA) helps release viral particles from infected cells (Choice C is incorrect).
4. Tamiflu is a Neuraminidase (NA) inhibitor, which prevents the release of viral particles, aiding in the treatment of influenza infections (Choice D).
Which of the following is a characteristic of CTL?
- A. They kill target cells through recognition of peptide-MHC class I complexes
- B. They die in the process of killing a target cell
- C. They can kill target cells by activating complement
- D. They carry out their effector function in secondary lymphoid tissues
Correct Answer: A
Rationale: The correct answer is A because cytotoxic T lymphocytes (CTLs) kill target cells by recognizing specific peptide antigens presented on major histocompatibility complex (MHC) class I molecules. This recognition triggers the CTLs to release cytotoxic molecules that induce apoptosis in the target cells. Choice B is incorrect because CTLs do not die in the process of killing target cells; they survive to continue their immune response. Choice C is incorrect as CTLs do not kill target cells by activating complement, but rather through direct cell-cell contact. Choice D is incorrect because CTLs carry out their effector function in peripheral tissues where they encounter target cells, not specifically in secondary lymphoid tissues.
The three antibiotic-resistant bacteria that are of most current concern in North America are ____________________, ____________________, and ____________________.
- A. Methicillin-resistant Staphylococcus aureus (MRSA)
- B. Carbapenem-resistant Enterobacteriaceae (CRE)
- C. Vancomycin-resistant Enterococcus (VRE)
- D. All of the above
Correct Answer: D
Rationale: The correct answer is all of the above. MRSA, CRE, and VRE are among the most concerning antibiotic-resistant bacteria in North America due to their prevalence and difficulty in treatment.