What was Edward Jenner's major contribution to immunology?

Correct Answer: C

Rationale: Edward Jenner's major contribution to immunology was developing the smallpox vaccine. He introduced the concept of vaccination by using cowpox to protect against smallpox. This marked the beginning of modern immunization. Discovering antibodies (A) and proposing innate immunity theory (B) were not directly attributed to Jenner. Discovering the germ theory of disease (D) was later proposed by Louis Pasteur and Robert Koch, not Jenner. Overall, choice C is correct as it aligns with Jenner's groundbreaking work in immunization.

Correct Answer: B

Rationale: The correct answer is B: It is a dynamic field, continually evolving through research. Immunology is constantly evolving due to new discoveries and advancements in technology. Research in immunology leads to a deeper understanding of the immune system and its interactions with pathogens, cancer, and other diseases. This ongoing evolution is essential for the development of new treatments and vaccines. Explanation of why other choices are incorrect: A: It is largely static, with few modern discoveries - This is incorrect as immunology is a rapidly advancing field with numerous breakthroughs and discoveries. C: It exclusively studies pathogen biology - This is incorrect as immunology also encompasses the study of the immune system's responses to various stimuli, not just pathogens. D: It focuses solely on innate immunity - This is incorrect as immunology covers both innate and adaptive immunity, as well as the interactions between them.

Correct Answer: B

Rationale: The correct answer is B: Classical pathway. This pathway is activated by immune complexes containing IgG or IgM. When these antibodies bind to antigens, they trigger the classical pathway by forming a complex that activates C1q, initiating a cascade of reactions leading to inflammation and opsonization. The alternative pathway (A) is activated by microbial surfaces, while the lectin pathway (C) is activated by mannose-binding lectin binding to carbohydrates on pathogens. The terminal pathway (D) involves the formation of the membrane attack complex.

Correct Answer: D

Rationale: The correct answer is D, MHC molecules. PAMPs are conserved molecules found on pathogens that can trigger an immune response. MHC molecules are not PAMPs; they are part of the host's immune system used to present antigens to T cells. LPS, peptidoglycan, and viral RNA are examples of PAMPs as they are specific molecules found on pathogens that can be recognized by pattern recognition receptors on immune cells to initiate an immune response.

Correct Answer: B

Rationale: The correct answer is B: Recognition of PAMPs via PRRs. Innate immunity distinguishes self from non-self by recognizing Pathogen-Associated Molecular Patterns (PAMPs) via Pattern Recognition Receptors (PRRs). This recognition triggers an immediate response to eliminate potential threats. Choices A, C, and D are incorrect because somatic recombination is a process in adaptive immunity, MHC molecules present antigens for recognition by T cells in adaptive immunity, and antibody production is part of adaptive immunity involving B cells.