What is the primary function of white blood cells?

Correct Answer: B

Rationale: The correct answer is B: "To fight infection." White blood cells are primarily responsible for fighting infections and foreign invaders in the body, making them a critical component of the immune system. Choice A, "To carry oxygen," is incorrect as red blood cells are responsible for oxygen transport. Choice C, "To transport nutrients," is incorrect as this function is mainly attributed to blood plasma and other specialized cells. Choice D, "To transport waste," is also incorrect as waste removal is primarily handled by the kidneys and the lymphatic system, not white blood cells.

Correct Answer: B

Rationale: The correct answer is Iron. Iron is essential for the formation of hemoglobin, the protein in red blood cells that binds and transports oxygen throughout the body. Calcium (Choice A), Potassium (Choice C), and Sodium (Choice D) are not directly involved in the formation of hemoglobin and its oxygen-carrying function.

Correct Answer: B

Rationale: The correct answer is B: "To fight infection." White blood cells are primarily responsible for fighting infections and foreign invaders in the body, making them a critical component of the immune system. Choice A, "To carry oxygen," is incorrect as red blood cells are responsible for oxygen transport. Choice C, "To transport nutrients," is incorrect as this function is mainly attributed to blood plasma and other specialized cells. Choice D, "To transport waste," is also incorrect as waste removal is primarily handled by the kidneys and the lymphatic system, not white blood cells.

Correct Answer: B

Rationale: Vitamin D is the correct answer. When the skin is exposed to sunlight, it triggers a process where a form of cholesterol in the skin is converted into vitamin D. This vitamin plays a crucial role in aiding calcium absorption in the gut, which is essential for maintaining strong and healthy bones. Vitamin A (Choice A) is important for vision and immune function but is not produced by sunlight exposure. Vitamin K (Choice C) is known for its role in blood clotting and bone metabolism, but it is not produced by sunlight. Vitamin E (Choice D) is an antioxidant that protects cells from damage but is not synthesized in the skin through sunlight exposure.

Correct Answer: B

Rationale: The correct answer is B, Hip. The hip joint is a ball-and-socket joint, characterized by the spherical head of one bone (femur) fitting into the cup-like socket of another bone (pelvis). This structure allows for a wide range of motion in multiple directions, such as flexion, extension, abduction, adduction, and rotation. Choices A, C, and D are incorrect as the knee, elbow, and wrist joints are not ball-and-socket joints. The knee is a hinge joint, allowing flexion and extension movements. The elbow is a hinge joint that allows flexion and extension, while the wrist is a condyloid joint permitting flexion, extension, abduction, adduction, and circumduction movements.

Correct Answer: C

Rationale: The correct answer is the humerus. The humerus is the long bone located in the upper arm, between the shoulder and elbow. Option A, Femur, is incorrect as it is the long bone found in the thigh. Option B, Tibia, is incorrect as it is a long bone found in the lower leg. Option D, Radius, is incorrect as it is a bone located in the forearm, not the upper arm.

Correct Answer: B

Rationale: The correct answer is B: To filter waste from the blood. The kidneys play a crucial role in filtering waste products and excess substances from the blood to form urine, which helps maintain fluid balance and eliminate toxins from the body. Choice A is incorrect because regulating body temperature is primarily controlled by the skin and other mechanisms. Choice C is incorrect as hormone production is mainly attributed to other organs like the endocrine glands. Choice D is incorrect as the transportation of oxygen is primarily facilitated by the lungs and circulatory system, not the kidneys.

Correct Answer: B

Rationale: The correct answer is B: ATP energy. During cellular respiration, glucose is broken down to produce ATP, which is the primary energy currency of cells. While oxygen is required for cellular respiration to occur, it is not an end product but rather a reactant. Carbon dioxide and water are byproducts of cellular respiration, alongside ATP. Therefore, options A, C, and D are incorrect as they are not end products of cellular respiration.

Correct Answer: B

Rationale: The correct statement about the pericardium is that it is double-walled, not single-walled. Choice A is correct because the pericardium does allow the heart to work in a relatively friction-free environment, reducing friction during heartbeats. Choice C is correct as the pericardium helps prevent the overfilling of the heart with blood. Choice D is also correct as the pericardium serves to protect and anchor the heart in place within the chest cavity.