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Normal mice injected with high doses of LPS die of septic shock. Mice resistant to LPS-induced septic shock have a mutation in which receptor?
- A. TLR4
- B. TLR5
- C. NOD1
- D. NOD2
Correct Answer: A
Rationale: Step 1: TLR4 is the receptor for lipopolysaccharide (LPS), a component of gram-negative bacteria.
Step 2: The question states that normal mice injected with high doses of LPS die, indicating TLR4 activation.
Step 3: Mutations in TLR4 can confer resistance to LPS-induced septic shock.
Step 4: Therefore, the correct answer is A: TLR4, as it is directly involved in recognizing LPS and triggering septic shock.
Summary: B: TLR5 does not specifically bind LPS. C: NOD1 and D: NOD2 are involved in intracellular recognition of bacterial components, not LPS.
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In reference to the flow diagram below respond to the following question. The annotation A refers to which sites
- A. Annealing
- B. Melting
- C. Restriction
- D. RNAse
Correct Answer: C
Rationale: The correct answer is C: Restriction. In a flow diagram, the annotation "Restriction" likely indicates the site where a DNA molecule is being cut by a restriction enzyme. This process is essential in molecular biology for DNA manipulation.
Choice A: Annealing involves the process of complementary DNA strands coming together, usually during PCR or hybridization.
Choice B: Melting refers to the separation of double-stranded DNA into single strands, often seen in denaturation steps.
Choice D: RNAse is an enzyme that specifically degrades RNA molecules, not involved in the DNA manipulation processes indicated in the diagram.
Which T cell type helps activate B cells?
- A. Cytotoxic T cells
- B. Helper T cells
- C. Regulatory T cells
- D. Memory T cells
Correct Answer: B
Rationale: The correct answer is B: Helper T cells. Helper T cells play a crucial role in activating B cells by releasing cytokines that stimulate B cell proliferation and differentiation into plasma cells, which produce antibodies. Cytotoxic T cells (A) are involved in directly killing infected cells. Regulatory T cells (C) suppress immune responses. Memory T cells (D) are responsible for maintaining immunological memory for future responses. Thus, Helper T cells are the key cell type that helps activate B cells.
Viral antigenic shift
- A. Is caused by multiple random mutations
- B. Is caused by a single mutation
- C. It affects only internal viral proteins not recognized by preexisting antibodies
- D. It refers to the appearance of new HA variants not recognized by preexisting antibodies
Correct Answer: D
Rationale: Step 1: Viral antigenic shift involves major changes in the surface proteins of the virus, particularly the hemagglutinin (HA) protein.
Step 2: These changes result in the emergence of new variants that are not recognized by preexisting antibodies.
Step 3: This process is distinct from antigenic drift, which involves minor changes due to random mutations.
Step 4: Choice D correctly states that viral antigenic shift refers to the appearance of new HA variants not recognized by preexisting antibodies.
Summary: Choice A is incorrect because viral antigenic shift is not caused by multiple random mutations. Choice B is incorrect as antigenic shift involves major changes, not a single mutation. Choice C is incorrect as it affects surface proteins like HA, not just internal proteins.
CD8+ T cells
- A. Have cytotoxic function
- B. Recognize antigen in the context of MHC I molecules
- C. Can kill virus-infected cells
- D. Can kill tumor cells
Correct Answer: E
Rationale: I apologize, but the question you provided does not have a correct answer option listed. Could you please provide the correct answer option for me to provide a detailed explanation of why it is correct and summarize why the other choices are incorrect?
Which statement indicates that the patient needs further instruction about application of ice to a sprain?
- A. "I know this ice will reduce the swelling."
- B. "I will keep the ice on this knee for the rest of the day."
- C. "I will use the ice as you have directed for 24 hours."
- D. "I can elevate my leg and use ice to reduce swelling."
Correct Answer: B
Rationale: The correct answer is B because keeping ice on the knee for the rest of the day can lead to skin damage or frostbite. Choice A is correct as it acknowledges the purpose of ice in reducing swelling. Choice C shows understanding of using ice as directed. Choice D indicates proper understanding of combining elevation with ice for swelling reduction.