Nokea
Colostrum, the yellowish fluid, secreted by mother during the initial days of lactation is very essential to impart immunity to the newborn infants because it contains:
- A. Natural killer cells
- B. Monocytes
- C. Macrophages
- D. Immunoglobulin A
Correct Answer: D
Rationale: The correct answer is D: Immunoglobulin A. Colostrum contains high levels of Immunoglobulin A (IgA), which is crucial for imparting passive immunity to the newborn. IgA helps protect the infant's mucosal surfaces from infections. Natural killer cells, monocytes, and macrophages are not typically found in colostrum and are not responsible for conferring immunity to the newborn.
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To produce better flu vaccines, we want:
- A. To block spreading of the infection by inducing a cytotoxic T cell response that would directly prevent viral entry into uninfected cells
- B. To induce the formation of strain-specific neutralizing antibodies that would prevent viral entry into uninfected cells
- C. To induce antibodies able to recognize HA across different strains by targeting less variable regions of HA
- D. All of the above is reasonably expected to improve the success of flu vaccines
Correct Answer: D
Rationale: The correct answer is D because all the options contribute to improving flu vaccines. A cytotoxic T cell response can help block viral spread, strain-specific neutralizing antibodies can prevent viral entry, and targeting less variable regions of HA with antibodies can improve recognition across strains. Each approach addresses different aspects of the immune response to enhance vaccine efficacy. Therefore, combining these strategies can lead to a more comprehensive and effective flu vaccine. Options A, B, and C alone are not sufficient as they only target specific aspects of the immune response, while option D encompasses a holistic approach for better vaccine success.
Why don't we have a successful HIV vaccine?
- A. The high mutation rate of HIV interferes with the generation of a protective memory response
- B. Because it is difficult to induce mucosal immunity that would block the sexual transmission of the virus
- C. Because HIV targets immune cells
- D. All of the above represent challenges for the creation of an effective HIV vaccine
Correct Answer: D
Rationale: The correct answer is D because all the statements in choices A, B, and C are valid reasons why we don't have a successful HIV vaccine.
A: HIV has a high mutation rate, making it challenging to generate a protective memory response.
B: Inducing mucosal immunity is difficult to block sexual transmission, a common route of HIV infection.
C: HIV targets immune cells, which hinders the immune system's ability to mount an effective response.
Therefore, all these factors combined pose significant challenges for creating an effective HIV vaccine.
The 'major histocompatibility complex' (MHC) proteins involved in antigen presentation to T cells were first noted during studies of:
- A. Innate immunity
- B. Allergy
- C. Transplantation
- D. Autoimmunity
Correct Answer: C
Rationale: The correct answer is C: Transplantation. MHC proteins play a crucial role in transplant rejection by presenting antigens to T cells, initiating an immune response against foreign tissues. This discovery was significant in understanding transplant immunology. Choices A, B, and D are incorrect because innate immunity involves nonspecific defense mechanisms, allergies are mediated by IgE antibodies, and autoimmunity involves the immune system attacking self-antigens, none of which directly relate to the discovery of MHC proteins in transplantation studies.
Which group(s) of fungi do not generally produce sexual reproductive structures and are also sometimes known as imperfect fungi?
- A. Ascomycotina
- B. Oomycetes
- C. Zygomycotina
- D. Hyphochridiomycetes
Correct Answer: E
Rationale: I'm sorry, but the correct answer is not provided in the choices given (A, B, C, D). Can you please provide the correct answer so that I can help you with the detailed explanation and summary of why the correct answer is correct and the others are incorrect?
Which of the following statements is NOT true
- A. Light chains isotypes are functionally different
- B. The antigen binding site of a B cell receptor is identical to the antigen binding site of antibodies secreted by the same B cell
- C. Both heavy and light chain domains assume a compact barrel structure
- D. The hinge region assumes a more open and flexible structure
Correct Answer: A
Rationale: The correct answer is A: Light chains isotypes are functionally different. This statement is NOT true because light chain isotypes (kappa and lambda) have distinct primary structures but serve the same function in antigen binding. The heavy chain determines the effector function of antibodies. The other choices are correct: B) The antigen binding site of a B cell receptor is identical to the antigen binding site of antibodies secreted by the same B cell, as both use the same variable regions for antigen recognition. C) Both heavy and light chain domains assume a compact barrel structure, which is essential for antibody stability and function. D) The hinge region assumes a more open and flexible structure, allowing antibodies to bind antigens at different orientations.