Neutrophils cannot

Correct Answer: D

Rationale: Neutrophils lack the ability to present antigens to T cells due to their short lifespan and absence of major histocompatibility complex (MHC) class II molecules. This process requires MHC class II presentation, which is typically done by antigen-presenting cells such as dendritic cells, macrophages, and B cells. Neutrophils primarily function in phagocytosis, releasing reactive oxygen species (ROS), defensins, and neutrophil extracellular traps (NETs) to combat pathogens. Thus, the correct answer is D. Other choices are incorrect because neutrophils are capable of producing ROS (A), defensins (B), and NETs (C).

Correct Answer: C

Rationale: The correct answer is C: Ethylene. Ethylene is indeed a gaseous plant hormone produced during the combustion of natural gas. It plays a crucial role in various plant processes such as fruit ripening, senescence, and stress responses. A: Auxin is not a gaseous hormone and is primarily involved in promoting cell elongation and root growth. B: Gibberellins are not gaseous hormones and mainly regulate plant growth processes like stem elongation and seed germination. D: The statement "All above" is incorrect as auxin and gibberellins are not gaseous hormones, only ethylene fits the description. Therefore, choice C, Ethylene, is the correct answer as it is the gaseous by-product of natural gas combustion and a plant hormone.

Correct Answer: D

Rationale: The correct answer is D: All above. The vibrations from sound waves are amplified by the eardrum, Anvil (also known as the Incus), and Stirrup (also known as the Stapes), which are the three tiny bones in the middle ear. The sound waves travel through the ear canal and hit the eardrum, causing it to vibrate. The vibration is then transmitted through the Anvil to the Stirrup, which amplifies the vibrations and sends them to the inner ear. Each of these three components plays a crucial role in the process of amplifying sound vibrations for better auditory perception. Therefore, all three choices are correct in this context.

Correct Answer: B

Rationale: The correct answer is B: Thrombocytopenia, which refers to an abnormal decrease in platelets. Platelets are crucial for blood clotting. Leukopenia (A) is a decrease in white blood cells, not platelets. Anemia (C) is a decrease in red blood cells, not platelets. Hemolysis (D) is the breakdown of red blood cells, not related to platelet count. Therefore, B is the correct answer as it specifically addresses a decrease in platelet count, leading to potential bleeding issues.

Correct Answer: B

Rationale: The correct answer is B, the discovery that cell-free serum could transfer immunity. This finding led humoralists to dominate because it supported the idea of circulating antibodies in the serum being responsible for immunity. This concept aligned with the humoralist theory, which focused on the role of antibodies in immune response. The ability of cell-free serum to transfer immunity provided direct evidence for humoralists' beliefs. Choice A (The demonstration of the Germ Theory of disease) is incorrect because while it was a significant advancement in understanding disease, it did not directly impact the argument between cellularists and humoralists regarding the immune response. Choice C (The discovery of the tuberculin reaction) is incorrect as it was more relevant to the understanding of the immune response to tuberculosis specifically, rather than the broader debate between cellularists and humoralists. Choice D (The determination of the antibody structure) is incorrect because while understanding antibody structure is crucial, it did not have as direct an impact on the dominance of