Correct Answer: C

Rationale: The correct answer is C: Cortisol. Cortisol, produced by the adrenal glands, is involved in the body's stress response. It helps regulate metabolism, immune function, and the body's response to stressors by increasing blood sugar levels, suppressing the immune system, and aiding in the metabolism of fats, carbohydrates, and proteins. Choice A, Insulin, is a hormone that regulates blood sugar levels and is not primarily involved in the stress response. Choice B, Adrenaline, is also known as epinephrine and is involved in the fight-or-flight response, which is related to stress but is not the main hormone in the body's stress response. Choice D, Melatonin, is a hormone that regulates sleep-wake cycles and is not directly involved in the stress response.

Correct Answer: B

Rationale: The correct answer is B: To produce bile. The liver's primary function in the digestive system is to produce bile. Bile is essential for the digestion and absorption of fats in the small intestine. It helps emulsify fats, making it easier for enzymes to break them down into smaller molecules for absorption. Choices A, C, and D are incorrect as storing glucose is primarily done in the liver for energy maintenance, detoxifying harmful substances is a function of the liver related to metabolism but not specifically in the digestive system, and absorbing nutrients is mainly done in the small intestine rather than the liver.

Correct Answer: C

Rationale: The correct answer is the front portion of the parietal lobe. The motor cortex, located in this area, is responsible for planning, controlling, and executing voluntary movements. It plays a crucial role in coordinating the body's movement. Choice A, the top, middle portion of the parietal lobe, is incorrect as this region is more involved in processing sensory information rather than controlling movement. Choice B, the back of the head, is incorrect as it typically refers to the occipital lobe responsible for processing visual information. Choice D, around the auditory cortex, is incorrect as the auditory cortex is primarily involved in processing auditory information, not controlling body movement.

Correct Answer: B

Rationale: The correct answer is the Glomerulus. The glomerulus is a network of tiny blood vessels located within the Bowman's capsule. It acts as the initial filtering component in the nephron, filtering blood and allowing waste products and excess substances to pass through to form urine. Choice A, Nephron, is incorrect as the nephron is the structural and functional unit of the kidney composed of several parts, including the glomerulus. Choice C, Bowman's capsule, is where the glomerulus is located, but it is not the structure responsible for filtering blood. Choice D, Loop of Henle, plays a role in reabsorption of water and electrolytes but is not the primary structure for blood filtration in the kidney.

Correct Answer: A

Rationale: The biceps brachii muscle is the primary muscle responsible for flexing the forearm at the elbow joint. When the biceps brachii contracts, it causes the forearm to move towards the upper arm, resulting in flexion at the elbow. In contrast, the triceps brachii is responsible for extending the forearm, the deltoid muscle is primarily involved in shoulder movements, and the brachialis muscle also aids in flexion of the forearm but to a lesser extent compared to the biceps brachii.