Nokea
VDJ gene rearrangement takes place in
- A. Germinal Centers
- B. Lymph Nodes
- C. Bone marrow
- D. Spleen
Correct Answer: C
Rationale: Rationale: VDJ gene rearrangement occurs during lymphocyte development to generate diverse antigen receptors. This process occurs in the bone marrow, specifically in the early stages of B cell development. In the bone marrow, B cell precursors undergo VDJ recombination to create unique antibody specificity. Germinal centers are sites for B cell activation and proliferation, not gene rearrangement. Lymph nodes and spleen are secondary lymphoid organs where mature lymphocytes are activated, not where VDJ recombination occurs.
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A nurse is taking care of a client with cancer and is teaching about the types of drugs that promote the natural production of blood cells in people whose own hematopoietic functions have become compromised. What class of drugs are these?
- A. Tumor necrosis factors
- B. Colony-stimulating factors
- C. Interferons
- D. Interleukins
Correct Answer: B
Rationale: Colony-stimulating factors stimulate the production of blood cells which is crucial for clients with compromised hematopoietic function such as those undergoing chemotherapy.
Auxin hormones act as
- A. promotes seedling elongation
- B. is transported downward through a plant
- C. affects cell elongation in roots at lower concentrations
- D. all above
Correct Answer: D
Rationale: The correct answer is D because auxin hormones play a crucial role in promoting seedling elongation (A), are transported downward through a plant (B), and affect cell elongation in roots at lower concentrations (C). Auxins are known for their ability to stimulate cell growth and elongation, which is essential for seedling growth. They are also transported in a polar manner from the shoot tip downwards, influencing various plant processes along the way. Additionally, auxins regulate root growth by promoting cell elongation at lower concentrations. Therefore, all the statements (A, B, and C) are supported by the functions of auxin hormones, making option D the correct choice.
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.
What is not true about Salmonella thyphimurium?
- A. It is the causal agent of "hamburger disease"
- B. It is the second most common cause of food poisoning
- C. It is able to induce its own uptake by manipulating the actin cytoskeleton of host cells
- D. It is able to survive inside the phagosomes by manipulating the host actin cytoskeleton
Correct Answer: A
Rationale: The correct answer is A: It is the causal agent of "hamburger disease." Salmonella typhimurium is not the causal agent of "hamburger disease." Instead, Escherichia coli O157:H7 is the primary causal agent of this particular foodborne illness. Salmonella typhimurium is commonly associated with causing salmonellosis. Therefore, choice A is incorrect. Choices B, C, and D are all true statements about Salmonella typhimurium. It is the second most common cause of food poisoning, it is able to induce its own uptake by manipulating the actin cytoskeleton of host cells, and it is able to survive inside the phagosomes by manipulating the host actin cytoskeleton.
What type of antibodies predominate in the secondary immune response?
- A. IgM
- B. IgE
- C. IgG
- D. IgD
Correct Answer: C
Rationale: The correct answer is C: IgG. In the secondary immune response, IgG antibodies predominate due to memory B cells rapidly producing them upon re-exposure to the same antigen. IgG provides long-lasting immunity and is more efficient in neutralizing pathogens. IgM (A) is the primary antibody in the initial immune response. IgE (B) is involved in allergic reactions. IgD (D) functions as a receptor on B cells.