Correct Answer: C

Rationale: Caloric intake for the average person typically declines with age due to factors such as changes in metabolism, muscle mass, and physical activity levels. As people age, their metabolism tends to slow down, and they may also experience a decrease in muscle mass and physical activity, leading to a reduced need for calories. Option A is incorrect because caloric intake generally decreases rather than increases with age. Option B is incorrect as it suggests a fluctuation in caloric intake that is not typically seen. Option D is incorrect as caloric needs usually change over a person's lifetime due to various factors.

Correct Answer: C

Rationale: Inflammation is a secondary defense mechanism for the body against pathogens. When tissues are injured or infected, inflammation occurs as a protective response involving increased blood flow, white blood cell migration, and tissue repair. This process helps contain and eliminate pathogens, preventing them from spreading further in the body. Tears (Choice A) are a primary defense containing lysozyme and other antimicrobial agents. Urine (Choice B) is typically considered a non-specific defense mechanism due to its flushing action in the urinary tract. Mucus (Choice D) acts as a physical barrier and traps pathogens, also considered a primary defense mechanism.

Correct Answer: D

Rationale: Copper is crucial for the formation of red blood cells as it is a component of enzymes involved in the production of hemoglobin. Hemoglobin, the protein in red blood cells responsible for transporting oxygen throughout the body, requires copper for its synthesis. A deficiency in copper can result in anemia due to insufficient production of red blood cells. Selenium, calcium, and magnesium do not play a direct role in red blood cell formation, making them incorrect choices for this question.

Correct Answer: A

Rationale: The vena cavae are large veins responsible for returning deoxygenated blood from the body to the heart. They empty into the right atrium of the heart. From the right atrium, the blood is then pumped into the right ventricle before being sent to the pulmonary circulation for oxygenation, making choice A, 'right atrium,' the correct answer. Choices B, C, and D are incorrect because the vena cavae do not empty into the ventricles of the heart; instead, they deliver blood to the atria.

Correct Answer: D

Rationale: Veins have the lowest blood pressure among the listed structures. This is because veins carry blood back to the heart at a slower rate compared to arteries, arterioles, and venules. The lower blood pressure in veins allows for the efficient return of blood to the heart despite the decreased pressure. Arteries have high blood pressure as they transport blood away from the heart at a rapid rate. Arterioles are smaller branches of arteries and contribute to resistance in the circulatory system, leading to a pressure drop. Venules are small blood vessels that collect blood from capillaries and gradually converge into veins, having slightly higher pressure than veins.