Correct Answer: B

Rationale: The gallbladder's main function is to store and concentrate bile produced by the liver. Bile is essential for the digestion and absorption of fats in the small intestine.
Therefore, the correct answer is B, as the gallbladder acts as a reservoir for bile rather than producing it.

Choices A, C, and D are incorrect because the gallbladder does not produce bile, detoxify harmful substances, or regulate blood sugar in the digestive system.

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: A

Rationale: The correct answer is the left ventricle. The left ventricle is the largest and strongest chamber of the heart. It pumps oxygenated blood to the entire body, making it a vital component of the circulatory system. The left atrium receives oxygen-rich blood from the lungs, the right ventricle pumps deoxygenated blood to the lungs for oxygenation, and the right atrium receives deoxygenated blood from the body.

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: B

Rationale: The correct answer is a ball and socket joint like the shoulder or hip joint, as it allows for movement in multiple directions, including rotation. This type of joint offers a high degree of mobility due to its structure, where the rounded end of one bone fits into the cup-like socket of another bone.

A hinge joint (
Choice
A) allows movement primarily in one plane, like the elbow or knee. A pivot joint (
Choice
C) allows for rotation around an axis, seen in the neck joint. A saddle joint (
Choice
D) enables movements in multiple directions but to a lesser extent compared to a ball and socket joint, found in the thumb joint.