Nokea
Which cellular structure is involved in digesting engulfed pathogens during phagocytosis?
- A. Lyosomes
- B. Golgi apparatus
- C. Endoplasmic reticulum
- D. Mitochondria
Correct Answer: A
Rationale: The correct answer is A: Lysosomes. Lysosomes contain enzymes that break down engulfed pathogens during phagocytosis. First, the pathogen is engulfed by the cell membrane forming a phagosome. Next, the phagosome fuses with a lysosome forming a phagolysosome where digestion occurs. Golgi apparatus (B) is involved in protein processing and packaging. Endoplasmic reticulum (C) is responsible for protein synthesis and lipid metabolism. Mitochondria (D) produce energy in the form of ATP.
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Which of the following statements about the functions of Ig is NOT correct
- A. IgM are the best at activating complement
- B. IgM bound to antigens are also the best at facilitating phagocytosis through the Fc receptor
- C. Antibodies can neutralize bacterial toxins
- D. Antibodies can inhibit binding of toxins to their receptors on host cells
Correct Answer: B
Rationale: The correct answer is B because IgG, not IgM, is the best at facilitating phagocytosis through the Fc receptor. IgM is the best at activating complement (A), antibodies can neutralize bacterial toxins (C), and antibodies can inhibit binding of toxins to their receptors on host cells (D). IgM primarily activates complement, while IgG is more efficient at facilitating phagocytosis through the Fc receptor. This distinction is crucial in understanding the functions of different immunoglobulins.
The class of an immunoglobulin
- A. is determined by Class I and Class II major histocompatibility complex proteins
- B. is determined by the carbohydrate attached to the light chain is
- C. determined by the antigen
- D. is determined by the heavy chain type
Correct Answer: D
Rationale: The correct answer is D because the class of an immunoglobulin is determined by the type of heavy chain it possesses. There are five main classes of immunoglobulins (IgG, IgA, IgM, IgD, IgE) which are defined by the heavy chain constant region. Different heavy chain types result in different effector functions and biological properties. Choices A, B, and C are incorrect because the class of an immunoglobulin is not determined by Class I and Class II major histocompatibility complex proteins, carbohydrate attached to the light chain, or the antigen. These factors may influence the function or specificity of the antibody, but they do not determine its class.
Which nutrients aid in capillary synthesis and collagen production by the fibroblasts in wound healing?
- A. Fats
- B. Proteins
- C. Vitamin C
- D. Vitamin A
Correct Answer: C
Rationale: Vitamin C plays a crucial role in collagen synthesis, which is essential for wound healing. It supports the formation of new blood vessels (angiogenesis) and strengthens connective tissue.
Developing T cells in the thymus can express
- A. Both CD4 and CD8
- B. Only CD4
- C. Only CD8
- D. Neither CD4 or CD8
Correct Answer: A
Rationale: The correct answer is A because developing T cells initially express both CD4 and CD8 co-receptors in the thymus. This stage is crucial for T cell maturation and selection. Eventually, T cells undergo positive and negative selection processes to become either CD4+ helper T cells or CD8+ cytotoxic T cells based on their specificity and function. Choices B and C are incorrect because T cells initially express both CD4 and CD8. Choice D is also incorrect as T cells do express either CD4 or CD8 during their development in the thymus.
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.