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.
You may also like to solve these questions
Match the following:
- A. 1-c, 2-d, 3-b, 4-a
- B. 1-b, 2-d, 3-c, 4-a
- C. 1-b, 2-d, 3-a, 4-c
- D. 1-d, 2-c, 3-a, 4-b
Correct Answer: C
Rationale: The correct answer is C: 1-b, 2-d, 3-a, 4-c.
1. The first match should be b, as it aligns with the order given.
2. The second match should be d, as it aligns with the order given.
3. The third match should be a, as it aligns with the order given.
4. The fourth match should be c, as it aligns with the order given.
Therefore, option C is the correct match based on the given order. Other choices are incorrect because they do not align with the given order of matches.
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.
An older adult has fallen and sprained his ankle in a local park. Which action should the responder perform first?
- A. Elevate the foot.
- B. Apply ice.
- C. Administer aspirin.
- D. Assist the patient with ambulation.
Correct Answer: A
Rationale: The correct action is to elevate the foot first. Elevating the foot helps reduce swelling and pain by promoting better circulation. This step is crucial in the initial management of a sprained ankle. Applying ice and administering aspirin can come after elevating the foot. Assisting with ambulation should only be considered after the initial measures are taken to address the sprained ankle.
Which molecule is essential for antigen presentation to T cells?
- A. Antibody
- B. Major Histocompatibility Complex (MHC)
- C. Complement protein C3
- D. Cytokines
Correct Answer: B
Rationale: The correct answer is B: Major Histocompatibility Complex (MHC). MHC molecules present antigens to T cells for immune response activation. They bind to antigenic peptides and present them on the cell surface for recognition by T cells. This is crucial for the immune system to distinguish between self and non-self antigens. Antibodies (A) are produced by B cells and do not directly present antigens to T cells. Complement protein C3 (C) is involved in the complement system for immune defense, not antigen presentation. Cytokines (D) are signaling molecules that regulate immune responses but do not directly present antigens to T cells.
EcoRI restriction endonuclease reactions produce fragments with
- A. 3' cohesive ends
- B. blunt ends
- C. 5' cohesive ends
- D. none of the options are correct
Correct Answer: C
Rationale: EcoRI recognizes the palindromic sequence GAATTC and cuts between G and A on both strands, producing 5' cohesive ends. Cohesive ends can base-pair with complementary ends, facilitating DNA ligation. Blunt ends (choice B) are produced by enzymes that cut both DNA strands at the same position. Choice A is incorrect as EcoRI produces 5' cohesive ends, not 3' cohesive ends. Choice D is incorrect as EcoRI does produce cohesive ends.