What is the primary function of the cardiovascular system?

Correct Answer: A

Rationale: The primary function of the cardiovascular system is to pump blood throughout the body, ensuring that oxygen and nutrients are delivered to tissues while removing waste products. This circulation is essential for maintaining overall health and proper functioning of the body's cells and organs. Choices B, C, and D are incorrect because while the cardiovascular system does deliver nutrients to tissues indirectly by transporting them in the blood, regulating body temperature is primarily the role of the endocrine and nervous systems, and protecting the body from infection is the main function of the immune system.

Correct Answer: B

Rationale: The correct answer is B: Detoxifying harmful substances. While the liver does produce bile for digestion and stores nutrients like glycogen, its primary function is to filter and detoxify blood coming from the digestive tract before passing it to the rest of the body. Therefore, choices A, C, and D are incorrect. Producing insulin is mainly done by the pancreas, digesting food is primarily the role of the stomach and intestines, and storing energy is a function of various organs like muscles and fat cells.

Correct Answer: B

Rationale: The correct answer is B: Hinge. A hinge joint, such as the one found at the elbow, allows for movement primarily in one plane, enabling flexion and extension similar to the movement of a door hinge. This joint structure permits bending and straightening of the arm, controlling the range of motion in a specific direction. Choices A, C, and D are incorrect. A ball and socket joint allows for multi-axial movement like the hip joint, a pivot joint allows for rotation around an axis like the joint between the first and second cervical vertebrae, and a saddle joint allows for movement in two planes at right angles to each other like the joint at the base of the thumb.

Correct Answer: B

Rationale: The medulla oblongata, situated in the brainstem, plays a crucial role in controlling essential functions like heart rate, blood pressure, and breathing. It contains vital cardiovascular and respiratory centers, making it the correct choice for the regulation of heart rate and blood pressure. The cerebellum is primarily involved in coordinating movement and balance, not in regulating heart rate and blood pressure. The hypothalamus is responsible for maintaining homeostasis, regulating body temperature, hunger, and thirst, but not specifically heart rate and blood pressure. The pons is involved in functions like sleep, respiration, and bladder control, not primarily in regulating heart rate and blood pressure.

Correct Answer: B

Rationale: The correct answer is B: Energy production. Mitochondria are known as the powerhouses of the cell because they generate adenosine triphosphate (ATP) through the process of cellular respiration. ATP is a molecule that stores and releases energy, providing the cell with the necessary energy for various activities and functions. Choices A, C, and D are incorrect. Protein synthesis primarily occurs in the ribosomes, breaking down waste is mainly carried out by lysosomes, and cell division is orchestrated by the nucleus and other organelles like the centrioles.