Cells involved in allergic reactions include

Correct Answer: D

Rationale: The correct answer is D, "All of the above." Mast cells, eosinophils, and basophils are all involved in allergic reactions. Mast cells release histamine, leading to inflammation. Eosinophils are involved in allergic responses and parasitic infections. Basophils release histamine and other inflammatory mediators. Therefore, all three cell types play a crucial role in allergic reactions. Choices A, B, and C alone are incorrect because each cell type individually participates in allergic reactions.

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: Food chains. A food chain depicts the flow of energy and nutrients from one organism to another in an ecosystem. It shows how energy is transferred from producers to consumers. Food network (B) is a more complex and interconnected system than a simple linear chain. Pyramid of power (C) represents the energy flow in an ecosystem, not the transfer of food. Levels of nutrition (D) is not a term commonly used to describe how organisms transfer food and energy.

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.