Which of the following is NOT true? The meeting of naïve T cells and dendritic cells:

Correct Answer: A

Rationale: The correct answer is A because the meeting of naïve T cells and dendritic cells is not facilitated by the presence of naïve B cells. Naïve T cells interact with dendritic cells in the paracortex of lymph nodes, not with naïve B cells. The movement of T cells along connective tissue networks aids in their interaction with dendritic cells, and this interaction may supply the T cell with activation Signal 1, which is essential for T cell activation. Overall, the incorrect choices (B, C, and D) are actually true statements regarding the meeting of naïve T cells and dendritic cells, making them incorrect options.

Correct Answer: C

Rationale: The correct answer is C: ROS (Reactive Oxygen Species) is not a PAMP (Pathogen-Associated Molecular Pattern) because it is not a specific molecular pattern derived from pathogens. PAMPs are recognized by the innate immune system to trigger an immune response. Viral dsRNA, peptidoglycan, and flagellin are all examples of PAMPs as they are specific molecules commonly found in pathogens that can be recognized by pattern recognition receptors (PRRs) on immune cells, leading to activation of the immune response.ROS, on the other hand, are reactive molecules produced by host cells in response to pathogens but are not specific molecular patterns derived from pathogens. Therefore, ROS is not considered a PAMP.

Correct Answer: B

Rationale: Step 1: Acute-phase proteins are a group of proteins produced by the liver in response to inflammation or infection. Step 2: Mannose binding lectin (MBL) is an acute-phase protein that plays a role in the innate immune response. Step 3: MBL binds to pathogens and activates the complement system to enhance immune responses. Step 4: Selectins are cell adhesion molecules, not acute-phase proteins. Step 5: Lysozyme is an enzyme that destroys bacterial cell walls, not typically classified as an acute-phase protein. Step 6: Defensins are antimicrobial peptides, not typically classified as acute-phase proteins. Summary: MBL is the correct choice as it is a well-known acute-phase protein involved in the immune response. Selectins, Lysozyme, and Defensins are not typically classified as acute-phase proteins and are involved in different functions.

Correct Answer: A

Rationale: The correct answer is A: IgM. During a primary immune response, IgM antibodies are the first class produced by plasma cells. IgM is the largest antibody and is effective at agglutinating pathogens. It is later followed by IgG production. IgE is involved in allergic reactions and parasitic infections, not typically produced in large amounts during a primary response. IgA is more abundant in mucosal tissues and secretions.

Correct Answer: D

Rationale: The correct answer is D because plant hormones are used in agriculture to control fruit production, ripening, dropping, and to produce seedless fruits. Choice A is correct as plant hormones regulate these processes. Choice B is also correct as certain plant hormones can induce seedless fruit formation. Choice C is incorrect as plant hormones are not typically used as weed killers in agriculture. Overall, the correct answer, D, encompasses all the agricultural uses of plant hormones listed in the other choices.