Nokea
Which of the following is not an outcome of phagocytosis in macrophages
- A. Respiratory burst
- B. Nitric oxide production
- C. Antigen presentation
- D. Complement activation
Correct Answer: D
Rationale: The correct answer is D: Complement activation. Phagocytosis by macrophages involves engulfing and digesting pathogens. Complement activation occurs through a separate pathway involving a series of proteins that enhance the immune response. Phagocytosis does not directly lead to complement activation. Choices A, B, and C are outcomes of phagocytosis in macrophages: Respiratory burst involves production of reactive oxygen species, nitric oxide production helps destroy pathogens, and antigen presentation is important for activating other immune cells.
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What is a primary reason that the normal immune response fails to contain the HIV infection?
- A. CD4+ T cells become infected with HIV and are destroyed.
- B. The virus inactivates B cells, preventing the production of HIV antibodies.
- C. Natural killer cells are destroyed by the virus before the immune system can be activated.
- D. Monocytes ingest infected cells, differentiate into macrophages, and shed viruses in body tissues.
Correct Answer: A
Rationale: HIV specifically targets CD4+ T cells, depleting the immune system's ability to mount an effective response against pathogens.
What lineage do natural killer (NK) cells belong to?
- A. Myeloid lineage
- B. Erythroid lineage
- C. Lymphoid lineage
- D. Granulocyte lineage
Correct Answer: C
Rationale: The correct answer is C: Lymphoid lineage. NK cells are a type of lymphocyte that is part of the innate immune system. They are derived from common lymphoid progenitors in the bone marrow. NK cells play a crucial role in recognizing and killing infected or abnormal cells. Myeloid lineage (A) gives rise to cells like macrophages and granulocytes, not NK cells. Erythroid lineage (B) produces red blood cells, and granulocyte lineage (D) gives rise to neutrophils, basophils, and eosinophils, not NK cells. Therefore, the correct choice is C as NK cells originate from the lymphoid lineage.
A patient with chronic kidney disease has hyperphosphatemia. What is a commonly associated electrolyte imbalance?
- A. Hypokalemia
- B. Hyponatremia
- C. Hypocalcemia
- D. Hypomagnesemia
Correct Answer: C
Rationale: Hyperphosphatemia binds calcium, lowering its availability and causing hypocalcemia in patients with chronic kidney disease.
The activation of naïve T cells takes place in:
- A. Germinal centers
- B. Primary lymphoid tissues
- C. Secondary lymphoid tissues
- D. None of the above
Correct Answer: C
Rationale: The correct answer is C: Secondary lymphoid tissues. Naïve T cells are activated in secondary lymphoid tissues such as lymph nodes and spleen. These tissues are where T cells encounter antigen-presenting cells, receive co-stimulatory signals, and undergo clonal expansion to differentiate into effector T cells. Germinal centers are primarily for B cell responses. Primary lymphoid tissues (bone marrow and thymus) are where T cells mature but not where activation occurs. Choice D is incorrect as naïve T cell activation does occur in secondary lymphoid tissues.
The annotation C refers to which DNA component?
- A. Vector DNA
- B. Plasmid DNA
- C. Chromosomal DNA
- D. Recombinant DNA
Correct Answer: C
Rationale: The correct answer is C: Chromosomal DNA. Chromosomal DNA refers to the DNA found in the chromosomes of an organism's nucleus, carrying the majority of its genetic information. In molecular biology, the annotation C typically refers to the chromosomal DNA of the organism being studied. Plasmid DNA (choice B) and vector DNA (choice A) are extrachromosomal DNA elements that are separate from the chromosomal DNA. Recombinant DNA (choice D) is a DNA molecule formed by combining DNA from different sources, which can include chromosomal, plasmid, or vector DNA. Therefore, the correct choice is C as it specifically refers to the chromosomal DNA component.