Nokea
The rearrangement of B cell antigen receptor genes occurs in
- A. Germinal centres
- B. Cortical areas of lymph nodes
- C. Bone marrow
- D. All secondary lymphoid organs
Correct Answer: C
Rationale: The rearrangement of B cell antigen receptor genes occurs in the bone marrow. This process involves the assembly of variable (V), diversity (D), and joining (J) gene segments to generate a diverse repertoire of B cell receptors. The bone marrow provides the necessary environment for this gene rearrangement to take place, ensuring the development of functional B cells. Germinal centers and cortical areas of lymph nodes are involved in B cell activation and differentiation, not gene rearrangement. While secondary lymphoid organs support B cell activation and immune responses, they are not specifically where the gene rearrangement occurs.
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Which immunoglobulins will initially protect a newborn baby of a breastfeeding mother (select all that apply)?
- A. IgA
- B. IgD
- C. IgE
- D. IgG
Correct Answer: A
Rationale: IgA is transferred through breast milk and provides mucosal immunity, while IgG crosses the placenta during pregnancy to provide systemic protection.
Which of the following is NOT a feature of T cells?
- A. They recognize three-dimensional structures of a pathogen
- B. Their receptors possess specificity
- C. Their receptors have one antigen-binding site
- D. Their antigen receptors are never secreted
Correct Answer: A
Rationale: The correct answer is A because T cells do not recognize three-dimensional structures of a pathogen. T cell receptors interact with processed antigen fragments presented by MHC molecules on antigen-presenting cells. Choice B is correct because T cell receptors possess specificity for antigens. Choice C is incorrect because T cell receptors have multiple antigen-binding sites. Choice D is incorrect as T cell receptors can be secreted as soluble forms.
The patient in a long arm cast (from below the shoulder to the wrist, with a 90-degree elbow flexion) complains of a burning sensation over the elbow. The nurse's initial intervention should be:
- A. Elevate the casted arm on pillows.
- B. Check to see if the cast is properly supported.
- C. Notify the charge nurse of developing pressure ulcer.
- D. Cut a "window" in the cast.
Correct Answer: B
Rationale: The correct answer is B: Check to see if the cast is properly supported. The burning sensation over the elbow could indicate nerve compression due to improper cast positioning. By checking if the cast is properly supported, the nurse can ensure that there is no pressure on the nerves causing the burning sensation. Elevating the casted arm (choice A) may not address the root cause of the burning sensation. Notifying the charge nurse of developing pressure ulcer (choice C) is premature without confirming the cause of the burning sensation. Cutting a "window" in the cast (choice D) should be a last resort after ruling out other issues.
The human retina contains rods and cone which are able to
- A. convert the photo power to the chemical power
- B. absorption of ultraviolet
- C. convert photo power to electrical form and send action potentials to the brain
- D. absorption of infrared
Correct Answer: C
Rationale: The correct answer is C because rods and cones in the human retina convert light energy into electrical signals through phototransduction, which are then sent as action potentials to the brain via the optic nerve. This process allows for visual information to be transmitted and processed by the brain. Choice A is incorrect as it refers to the conversion of light energy to chemical energy, which is not the primary function of rods and cones. Choice B is incorrect as rods and cones do not specifically absorb ultraviolet light. Choice D is incorrect as rods and cones do not absorb infrared light.
Which is not a PAMP?
- A. Viral dsRNA
- B. Peptidoglycan
- C. ROS
- D. Flagellin
Correct Answer: C
Rationale: The correct answer is C: ROS (Reactive Oxygen Species) is not a PAMP (Pathogen-Associated Molecular Pattern) because it is not a specific molecular pattern derived from pathogens. PAMPs are recognized by the innate immune system to trigger an immune response. Viral dsRNA, peptidoglycan, and flagellin are all examples of PAMPs as they are specific molecules commonly found in pathogens that can be recognized by pattern recognition receptors (PRRs) on immune cells, leading to activation of the immune response.ROS, on the other hand, are reactive molecules produced by host cells in response to pathogens but are not specific molecular patterns derived from pathogens. Therefore, ROS is not considered a PAMP.