The reason for naming the closed circulatory systems

Correct Answer: C

Rationale: The correct answer is C because a closed circulatory system means that blood stays confined to vessels, providing efficient transport and preventing blood loss. Option A is incorrect because a closed system does not have open vessels. Option B is incorrect because veins and arteries are part of both closed and open circulatory systems. Option D is incorrect because returning blood to the heart is a function of both closed and open circulatory systems.

Correct Answer: A

Rationale: The correct answer is A: Thrombosis. Thrombosis refers to the formation of a blood clot within a blood vessel. The process involves the coagulation of blood components to form a clot. This can lead to blockages in blood vessels, potentially causing serious health issues like stroke or heart attack. Choice B: Embolus refers to a blood clot that has traveled from its original site and lodged in a different blood vessel. Choice C: Hemorrhage is the medical term for bleeding. Choice D: Hemostasis refers to the body's process of stopping bleeding, not the formation of a blood clot.

Correct Answer: C

Rationale: Rationale: 1. Clonal selection theory states that specific lymphocytes are activated by antigens. 2. Upon activation, these lymphocytes proliferate to form a clone of cells specific to the antigen. 3. This increases the number of lymphocytes specific for the antigen. 4. Choice C correctly aligns with the essence of clonal selection theory. Summary: A: Incorrect - Clonal selection theory does not involve a single lymphocyte expressing multiple antigen receptors. B: Incorrect - Antigens do not influence the generation of antigen receptors, but rather activate specific lymphocytes. D: Incorrect - Clonal selection theory focuses on lymphocyte response to antigens, not neutrophil increase during infections.

Correct Answer: C

Rationale: TLR-3 detects viruses in endosomes. When a virus enters a host cell, it is often engulfed into endosomes. TLR-3 recognizes viral RNA within endosomes and triggers an immune response. Choices A and B are incorrect because TLR-3 does not detect viruses in the cytosol or extracellular space. Choice D is incorrect because TLR-3 specifically functions in endosomes to detect viral RNA.

Correct Answer: C

Rationale: The correct answer is C because pathogens are microorganisms that specifically cause disease in a host with normal immune functions. Pathogens have mechanisms to evade or overcome the host's immune system, leading to the development of diseases. Choices A and B are characteristics of both pathogens and non-pathogenic organisms. Choice D is incorrect because not all pathogens are transmitted between individuals of the same species; some pathogens can be transmitted from animals to humans or through environmental sources.