Nokea
Compared to antibodies produced in a primary response to a given antigen, the antibodies produced in a memory response are typically:
- A. More likely to be IgM
- B. More likely to be IgG, IgA and/or IgE
- C. Of lower affinity
- D. Two of these responses are correct
Correct Answer: B
Rationale: Step 1: Memory response produces antibodies of higher affinity due to affinity maturation.
Step 2: Memory response involves class switching, leading to production of IgG, IgA, and IgE.
Step 3: IgM is predominant in primary response, but memory response shifts towards other classes.
Summary: Choice B is correct as memory response produces antibodies of higher affinity and different classes. Choices A and C are incorrect as memory response does not typically result in more IgM or lower affinity antibodies. Choice D is incorrect as only choice B is accurate.
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NAD and FAD are hydrogen carriers, but cytochromes are electron carriers in bacteria. What happens to the protons (Hâº) in electron transport chains?
- A. They go into solution inside the cytoplasm.
- B. They are taken back by NAD and FAD.
- C. They are carried from cytochromes to oxygen to form water.
- D. They go into solution outside the cytoplasmic membrane.
Correct Answer: D
Rationale: The correct answer is D because in the electron transport chain, protons (H⁺) are pumped across the membrane to create a proton gradient. This gradient is utilized by ATP synthase to produce ATP. Therefore, protons go into solution outside the cytoplasmic membrane. Choices A and B are incorrect because protons do not simply stay in the cytoplasm or get taken back by NAD and FAD. Choice C is incorrect as protons do not directly form water when carried by cytochromes.
The bacterial cytoplasmic membrane contains:
- A. ester-linked phospholipids, but no sterols
- B. ester-linked phospholipids and sterols
- C. ether-linked phospholipids, but no sterols
- D. ether-linked phospholipids, sulfolipids, and glycolipids
Correct Answer: A
Rationale: The correct answer is A because bacterial cytoplasmic membranes typically contain ester-linked phospholipids but no sterols. Ester-linked phospholipids are the main component of bacterial cell membranes, providing structure and function. Sterols, like cholesterol, are not commonly found in bacterial membranes. Choice B is incorrect because sterols are not present in bacterial membranes. Choice C is incorrect because ether-linked phospholipids are more commonly found in archaea, not bacteria. Choice D is incorrect because sulfolipids and glycolipids are not primary components of bacterial cytoplasmic membranes.
The epitopes recognized by T cells are always:
- A. Conformational
- B. Linear
- C. On the antigen surface
- D. Buried inside the antigen
Correct Answer: B
Rationale: The correct answer is B: Linear. T cells recognize linear epitopes, which are sequences of amino acids displayed in a linear fashion on the antigen's surface. This recognition occurs through the T cell receptor binding to the linear epitope. Conformational epitopes (A) involve multiple amino acid residues brought together in a specific three-dimensional structure. Epitopes on the antigen surface (C) are correct, but not all T cell epitopes are necessarily on the surface. Epitopes buried inside the antigen (D) are not accessible to T cell receptors for recognition. Thus, the correct choice is B due to the linear presentation of epitopes for T cell recognition.
The nurse is preparing an injection for an individual who requires passive immunity. In which situation would passive immunity be indicated?
- A. For permanent immunity against a disease
- B. To overcome an allergic reaction that is relatively mild
- C. To have ready-made antibodies after an exposure to pathogens
- D. As a booster dose to stimulate the production of specific antibodies
Correct Answer: C
Rationale: Passive immunity is indicated when an individual needs immediate protection with ready-made antibodies after exposure to pathogens. This is the correct answer (C) as it provides immediate defense without waiting for the body to produce its antibodies. Choice A is incorrect because passive immunity is temporary, not permanent. Choice B is incorrect as it addresses treating allergic reactions, not providing immunity. Choice D is incorrect as a booster dose stimulates the body to produce its antibodies, not providing ready-made antibodies.
The earliest event of an inflammatory response is
- A. Release of chemokines
- B. Recruitment of neutrophils
- C. Activation of adaptive immunity
- D. Activation of TLRs
Correct Answer: D
Rationale: The correct answer is D: Activation of TLRs. The earliest event in an inflammatory response is the activation of Toll-like receptors (TLRs) by recognizing pathogen-associated molecular patterns (PAMPs). This triggers a signaling cascade leading to the release of pro-inflammatory cytokines and chemokines, which then recruit neutrophils to the site of infection. Activation of adaptive immunity (choice C) occurs later in the immune response, as it involves the activation of T and B cells. While chemokines (choice A) are involved in recruiting immune cells, their release is a consequence of TLR activation. Neutrophils (choice B) are recruited after the release of chemokines.