Correct Answer: A

Rationale: The correct answer is A: Removal of excess heat from the body. The circulatory system, which includes blood vessels and the heart, works with the integumentary system, which consists of the skin, to regulate body temperature by removing excess heat. This process involves blood vessels near the skin's surface dilating to release heat and constricting to conserve heat, a mechanism crucial for maintaining homeostasis. Option B, Hormonal regulation of blood pressure, is incorrect as it does not accurately describe the collaborative function of these systems in regulating body temperature. Option C, Transport of oxygen in the body, is incorrect as it focuses on a different function of the circulatory system. Option D, Production of red blood cells in the bone marrow, is incorrect as it pertains to the skeletal and hematopoietic systems, not the circulatory and integumentary systems working together to regulate body temperature.

Correct Answer: B

Rationale: The correct answer is B. Flies laying eggs in the food when it is left exposed to the air is a common occurrence and a logical explanation for the presence of fly larvae in spoiled food. Choice A is incorrect as food cannot evolve into fly larvae; fly larvae come from eggs laid by flies. Choice C is incorrect as fly larvae do not spontaneously generate from spoiled food but rather develop from eggs laid by flies. Choice D is incorrect as the presence of fly larvae in spoiled food is a real phenomenon, not merely imagined by people.

Correct Answer: B

Rationale: The correct answer is B: Activation energy. Catalysts function by reducing the activation energy needed for a chemical reaction to proceed. By lowering the activation energy, catalysts facilitate the reaction without being consumed themselves. Substrate energy, inhibitors, and promoters are not directly altered by catalysts in the same way activation energy is. Substrate energy refers to the energy of the reactants, which is not altered by catalysts. Inhibitors increase the activation energy required for a reaction, while promoters enhance the effectiveness of a catalyst but do not represent a quantity altered by catalysts.

Correct Answer: B

Rationale: The correct answer is B because a water molecule consists of two hydrogen atoms and one oxygen atom, which is a fundamental chemical property of water. The pH of water is not a property of the water molecule itself but rather a measure of its acidity or alkalinity. Choice C is incorrect as it describes a different molecule, not water. Choice D provides an incorrect chemical formula for water, which is H2O.

Correct Answer: D

Rationale: The integumentary system is responsible for controlling fluid loss through sweat, protecting deep tissues as the body's first line of defense, and synthesizing vitamin D when exposed to sunlight. The skin, hair, nails, and associated glands make up the integumentary system, which plays a crucial role in maintaining homeostasis and overall health. The skeletal system (Choice A) provides structural support and protection for internal organs but does not directly control fluid loss, protect deep tissues, or synthesize vitamin D. The muscular system (Choice B) is responsible for movement and stability but is not involved in the functions described. The lymphatic system (Choice C) is primarily responsible for immunity and fluid balance, not the specific functions mentioned in the question.