Which process involves the body's natural defense against inhaled dust and allergens?

Correct Answer: C

Rationale: Ciliary action refers to the process where tiny hair-like structures called cilia in the respiratory tract help to sweep away inhaled dust and allergens, preventing them from entering deeper into the lungs. This is a crucial part of the body's natural defense mechanism against respiratory irritants. Cellular respiration (A) is the process where cells use oxygen to produce energy, not a defense mechanism against inhaled particles. Gas exchange (B) involves the exchange of oxygen and carbon dioxide in the lungs, not specifically targeting inhaled dust and allergens. Bronchoconstriction (D) is the narrowing of the airways in response to irritants or allergens, which can lead to breathing difficulties, but it is not the primary defense mechanism against these particles.

Correct Answer: B

Rationale: The fallopian tubes are the structures that connect the ovaries to the uterus in the female reproductive system. These tubes serve as a pathway for the egg to travel from the ovary to the uterus, where fertilization typically occurs. Options (A) Urethra, (C) Vagina, and (D) Cervix are not the structures responsible for connecting the ovary to the uterus, making them incorrect choices for this question.

Correct Answer: C

Rationale: Lymph moves through the lymphatic vessels due to the presence of one-way valves within the vessels. These valves prevent the backflow of lymph and help propel the fluid forward as muscles contract and relax or due to breathing movements. Unlike blood circulation, the lymphatic system does not rely on the pumping action of the heart to move lymph. Choice A is incorrect because lymphatic circulation does not depend on the pumping action of the heart. Choice B is partly correct as muscle contractions and breathing movements do assist in propelling lymph, but the primary mechanism is the presence of one-way valves within the vessels, making choice C the most accurate answer. Choice D is incorrect as not all options listed contribute to how lymph moves through the lymphatic vessels.

Correct Answer: C

Rationale: Vaccines primarily function by stimulating the immune system to develop immunological memory to a specific pathogen. When a vaccine is administered, it exposes the immune system to a harmless version of a pathogen or a piece of it. This exposure triggers the immune response, leading to the production of antibodies and memory cells specific to that pathogen. Choice A is incorrect because vaccines do not create a physical barrier; rather, they prepare the immune system to recognize and fight specific pathogens. Choice B is incorrect as vaccines do trigger an immune response, but the primary goal is to create memory rather than inflammation. Choice D is incorrect as vaccines do not directly activate phagocytes; instead, they stimulate the immune system to generate a targeted response against a particular pathogen.

Correct Answer: C

Rationale: The epiglottis plays a crucial role during swallowing by covering the trachea to prevent food or liquid from entering the airway, which could lead to aspiration. By acting as a lid over the trachea, it ensures that food passes down the esophagus to the stomach, preventing it from entering the lungs. Choice A is incorrect as the swallowing reflex is a coordinated muscular action involving the tongue and throat muscles. Choice B is incorrect as grinding food into smaller pieces is primarily the function of the teeth and the initial stages of digestion. Choice D is incorrect as the storage of saliva for lubrication is not a function of the epiglottis, but rather involves salivary glands.