What is the role of enzymes in the body?

Correct Answer: B

Rationale: Enzymes are biological catalysts that facilitate and speed up chemical reactions in the body. They do not produce energy but enable various processes such as digestion and metabolism by lowering the activation energy required for reactions to occur. Choice A is incorrect because enzymes do not produce energy themselves but assist in energy production through reactions. Choice C is incorrect as enzymes do not primarily function in transporting molecules, although some may have a role in specific transport processes. Choice D is incorrect as the primary role of enzymes is not to repair tissues, but rather to catalyze biochemical reactions.

Correct Answer: B

Rationale: Vitamin D is the correct answer. It is essential for bone health as it helps in the absorption of calcium, a crucial mineral for maintaining strong and healthy bones. Adequate levels of Vitamin D are necessary to prevent conditions like osteoporosis and ensure optimal bone development and strength. Choice A, Vitamin A, is important for vision and immune function, but it is not directly related to bone health. Choice C, Vitamin C, is essential for collagen synthesis and immune function, but it is not primarily responsible for bone health. Choice D, Vitamin K, plays a role in blood clotting and bone metabolism, but Vitamin D has a more direct impact on bone health through its role in calcium absorption.

Correct Answer: B

Rationale: The correct answer is B: To store urine. The urinary bladder's primary function is to store urine produced by the kidneys until it is ready to be excreted from the body. It acts as a reservoir that temporarily holds urine until an appropriate time for elimination. Choices A, C, and D are incorrect because the urinary bladder does not filter waste from the blood, regulate fluid balance, or directly remove waste from the body. These functions are primarily carried out by the kidneys and other organs in the excretory system.

Correct Answer: B

Rationale: The correct answer is B: To store and concentrate bile. The gallbladder's primary function is to store and concentrate bile, which is produced by the liver. Bile is released into the small intestine to aid in the digestion and absorption of fats. It helps in emulsifying fats and facilitating their breakdown by enzymes for better absorption. Choices A, C, and D are incorrect because the gallbladder does not produce bile (it is produced by the liver), detoxify harmful substances, or directly break down fats. Its main role is to store and concentrate bile before releasing it into the small intestine.

Correct Answer: C

Rationale: The correct answer is C: 'To carry oxygen.' Hemoglobin in red blood cells binds to oxygen in the lungs and transports it to the tissues and organs throughout the body. This oxygen transport is crucial for cellular respiration and the overall functioning of the body. Choices A, B, and D are incorrect because hemoglobin's primary function is not to transport nutrients, fight infections, or produce energy in red blood cells.