Correct Answer: A

Rationale: The pharynx is a structure found in the upper respiratory tract. It serves as a common pathway for both air and food, playing a crucial role in directing air to the trachea and food to the esophagus. The larynx, trachea, and esophagus are important structures in the respiratory and digestive systems, but the pharynx specifically belongs to the upper respiratory tract, making it the correct answer.

Correct Answer: A

Rationale: The primary function of the nervous system is to transmit signals and coordinate body activities. It controls and regulates body functions by sending and receiving signals between different parts of the body, enabling responses to internal and external stimuli. This intricate network allows for communication between the brain, spinal cord, and the rest of the body, ultimately facilitating movement, sensation, thoughts, and various bodily functions. Choices B, C, and D are incorrect as they do not represent the primary function of the nervous system. Fighting infections is primarily the role of the immune system, producing hormones is the function of the endocrine system, and regulating body temperature involves mechanisms of thermoregulation within the body, not directly controlled by the nervous system.

Correct Answer: B

Rationale: The small intestine is the primary site for nutrient absorption in the digestive system. It is responsible for absorbing nutrients from the digested food into the bloodstream for distribution throughout the body. Therefore, the correct function of the small intestine is to absorb nutrients. Choice A is incorrect because the gallbladder stores bile, not the small intestine. Choice C is incorrect because the digestion process primarily occurs in the stomach and small intestine. Choice D is incorrect because while the small intestine does play a role in enzyme production, its primary function is nutrient absorption.

Correct Answer: A

Rationale: The correct answer is A: 'To produce bile.' The liver's primary role in the digestive system is to produce bile. Bile is essential for emulsifying fats, aiding in their digestion and absorption in the small intestine. Choice B is incorrect because while the liver does secrete some digestive enzymes, its primary function is bile production. Choice C is incorrect because while the liver does store glucose, it is not its primary function in the digestive system. Choice D is incorrect because the liver produces bile, but it does not store it.

Correct Answer: A

Rationale: The correct answer is A: Transporting oxygen. Hemoglobin, a protein found in red blood cells, plays a crucial role in transporting oxygen in the blood. It binds to oxygen in the lungs forming oxyhemoglobin and carries it to tissues and organs throughout the body. Once at the destination, hemoglobin releases the oxygen for cellular respiration, providing energy for various physiological processes. Choices B, C, and D are incorrect as hemoglobin's primary function is not carrying nutrients, clotting blood, or removing carbon dioxide. These functions are carried out by other components in the blood such as plasma proteins, platelets, and red blood cells, respectively.