Auxin hormones act as

Correct Answer: D

Rationale: The correct answer is D because auxin hormones play a crucial role in promoting seedling elongation (A), are transported downward through a plant (B), and affect cell elongation in roots at lower concentrations (C). Auxins are known for their ability to stimulate cell growth and elongation, which is essential for seedling growth. They are also transported in a polar manner from the shoot tip downwards, influencing various plant processes along the way. Additionally, auxins regulate root growth by promoting cell elongation at lower concentrations. Therefore, all the statements (A, B, and C) are supported by the functions of auxin hormones, making option D the correct choice.

Correct Answer: A

Rationale: The correct answer is A: Leukocytosis. Leukocytosis refers to an abnormal increase in white blood cells, indicating an immune response. Thrombocytosis (B) is an increase in platelets, not white blood cells. Anemia (C) is a decrease in red blood cells. Hemolysis (D) is the breakdown of red blood cells, not related to an increase in white blood cells. Therefore, A is the correct answer as it specifically relates to an abnormal increase in white blood cells.

Correct Answer: D

Rationale: Rationale: Robert Koch is correctly paired with developing techniques to grow pure bacterial cultures. Koch's work laid the foundation for bacteriology and allowed for the isolation and identification of specific disease-causing bacteria. This technique, known as Koch's postulates, revolutionized the field of microbiology by linking specific pathogens to specific diseases. Summary: A: Louis Pasteur - Incorrect. While Pasteur is known for his work in vaccination and pasteurization, the provided accomplishment is associated with Edward Jenner, not Pasteur. B: Paul Ehrlich - Incorrect. Ehrlich is known for his work on immunology and coined the term "magic bullet," but he did not identify lymphocytes as cells mediating adaptive immunity. C: MacFarlane Burnet - Incorrect. Burnet is known for his clonal selection theory, not the side-chain theory of antibodies as described in the choice.

Correct Answer: B

Rationale: The correct answer is B: TIR. This is because both TLR-4 and MyD88 contain a Toll/interleukin-1 receptor (TIR) domain, which mediates protein-protein interactions in the Toll-like receptor signaling pathway. The other options, such as A (CARD), C (LRR), and D (Immunoglobulin-like domain), are not present in both TLR-4 and MyD88 and do not play a significant role in their interaction in the signaling pathway. This makes B the most appropriate choice as it accurately identifies the common protein-protein interaction domain between TLR-4 and MyD88.

Correct Answer: D

Rationale: The correct answer is D, All of the above. C3b, C-reactive protein, and MBL can all function as complement initiators and opsonins. C3b is a key complement protein involved in both processes. C-reactive protein can activate complement and enhance phagocytosis. MBL can also activate complement and enhance phagocytosis by binding to pathogens. All choices can serve as both initiators of the complement cascade and as opsonins, making D the correct answer.