Nokea
The new parents of an infant born with Down syndrome ask the nurse what happened to cause the chromosomal abnormality. What is the best response by the nurse?
- A. During cell division of the reproductive cells there is an error causing an abnormal number of chromosomes.
- B. A mutation in one of the chromosomes created an autosomal recessive gene that is expressed as Down syndrome.
- C. An abnormal gene on one of the two chromosomes was transferred to the fetus, causing an abnormal chromosome.
- D. A process of translocation caused the exchange of genetic material between the two chromosomes in the cell, resulting in abnormal chromosomes.
Correct Answer: A
Rationale: Down syndrome is primarily caused by nondisjunction during meiosis, leading to an extra copy of chromosome 21.
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A 28-year-old male Gulf War veteran tells the nurse he gets a headache, sore throat, shortness of breath, and nausea when his girlfriend wears perfume and when he was painting her apartment. He is afraid he has cancer. What does the nurse suspect may be the patient’s problem?
- A. He has posttraumatic stress disorder.
- B. He has multiple chemical sensitivities.
- C. He needs to wear a mask when he paints.
- D. He is looking for an excuse to break up with his girlfriend.
Correct Answer: B
Rationale: Multiple chemical sensitivities could explain the patient's symptoms triggered by exposure to various chemicals.
Which of the following is necessary to produce a T-cell repertoire capable of interacting with self MHC molecules?
- A. Two of these responses are correct
- B. Positive selection
- C. Negative selection
- D. Induction of energy
Correct Answer: B
Rationale: Positive selection is necessary to produce a T-cell repertoire capable of interacting with self MHC molecules. During positive selection in the thymus, T-cells that can recognize self MHC molecules are retained, ensuring self-tolerance and functionality. Negative selection eliminates self-reactive T-cells. Induction of anergy is a state of T-cell unresponsiveness and does not contribute to the development of a functional T-cell repertoire. Choice A is incorrect as only positive selection is necessary for self MHC recognition.
Concerning multiple sclerosis (MS), which of the following is NOT correct
- A. Some HLA alleles confer susceptibility to MS
- B. A gender bias is observed with females more at risk for MS than males
- C. Exhibits a North-South gradient, with a higher incidence reported for populations living above the equator
- D. Affects mostly individuals over 65 yrs. of age
Correct Answer: D
Rationale: The correct answer is D because multiple sclerosis (MS) typically affects individuals between 20-50 years old, with the most common age of onset being between 20-40 years. MS is not primarily a disease of older individuals over 65 years. Choices A, B, and C are incorrect because various HLA alleles have been associated with MS susceptibility, females are indeed more at risk for MS than males, and there is a known North-South gradient in MS incidence, with higher rates reported for populations living farther from the equator.
TLR-3 detects viruses found in:
- A. Cytosol
- B. Extracellular space
- C. Endosomes
- D. All of the above
Correct Answer: C
Rationale: TLR-3 detects viruses in endosomes. When a virus enters a host cell, it is often engulfed into endosomes. TLR-3 recognizes viral RNA within endosomes and triggers an immune response. Choices A and B are incorrect because TLR-3 does not detect viruses in the cytosol or extracellular space. Choice D is incorrect because TLR-3 specifically functions in endosomes to detect viral RNA.
Lysozyme is NOT
- A. An enzyme present in secretions and tears
- B. A type of Defensin
- C. Part of the chemical innate barriers to infection
- D. A protein capable of dissolving the cell wall of bacteria
Correct Answer: B
Rationale: The correct answer is B because lysozyme is not a type of defensin. Lysozyme is an enzyme present in secretions and tears, part of chemical innate barriers to infection, and capable of dissolving the cell wall of bacteria. Defensins are a different type of antimicrobial peptides that function by disrupting the microbial cell membrane. Therefore, B is the correct answer as it does not accurately describe lysozyme's function.