Which vitamin is essential for the synthesis of collagen?

Correct Answer: A

Rationale: The correct answer is Vitamin C. Vitamin C is essential for the synthesis of collagen, a protein crucial for maintaining the structure and integrity of skin, blood vessels, and bones. It plays a key role in the hydroxylation of proline and lysine residues in collagen synthesis, which is necessary for the stability and strength of collagen fibers. Choice B: Vitamin D is essential for bone health and calcium absorption but is not directly involved in collagen synthesis. Choice C: Vitamin B12 is important for red blood cell formation and neurological function but is not directly related to collagen synthesis. Choice D: Vitamin K is necessary for blood clotting and bone metabolism but does not play a direct role in collagen synthesis.

Correct Answer: A

Rationale: There are four major types of tissues in the human body: epithelial, connective, muscle, and nervous tissues. Epithelial tissue covers body surfaces, connective tissue supports and binds other tissues together, muscle tissue enables movement, and nervous tissue allows for communication between different parts of the body. Choices B, C, and D are incorrect because the human body has four main types of tissues, not six, eight, or ten.

Correct Answer: B

Rationale: The large intestine's primary function is to absorb water from the remaining indigestible food matter that enters it from the small intestine. This absorption process helps in forming solid waste (feces) by compacting the material and preparing it for excretion. The large intestine does not secrete digestive enzymes, produce bile, or transport nutrients. Therefore, option B, 'To absorb water and form solid waste,' is the correct function of the large intestine in the digestive system.

Correct Answer: C

Rationale: The appendix is involved in the immune system as it is believed to play a role in maintaining and protecting beneficial gut bacteria, especially after gastrointestinal illnesses. This helps in restoring the balance of intestinal bacteria crucial for immune function. The heart (Choice A), bronchi (Choice B), and esophagus (Choice D) are not directly involved in the immune system's functions. The heart pumps blood, the bronchi are part of the respiratory system, and the esophagus is responsible for transporting food to the stomach.

Correct Answer: A

Rationale: The correct answer is ADH (antidiuretic hormone), also known as vasopressin. ADH helps regulate water balance in the body by controlling the amount of water reabsorbed by the kidneys. When there is a need to conserve water, ADH levels increase, leading to more water reabsorption and concentration of urine. Insulin is involved in regulating blood sugar levels, not water balance. Cortisol is a stress hormone that helps regulate metabolism and immune response, not water balance. Thyroxine is a thyroid hormone that regulates metabolism, growth, and development, not water balance.

Correct Answer: B

Rationale: The correct answer is B: 'To break down food.' The stomach plays a crucial role in the digestive system by breaking down food using gastric acid and digestive enzymes. This process transforms the food into a semi-liquid mixture known as chyme, which is further digested in the small intestine. Choices A, C, and D are incorrect because the stomach does not primarily absorb nutrients, produce bile, or store waste. These functions are carried out by other organs in the digestive system such as the small intestine, liver, and large intestine, respectively.

Correct Answer: B

Rationale: The correct answer is B: To absorb nutrients. The small intestine's main role in the digestive system is to absorb nutrients from digested food. It has specialized structures, such as villi and microvilli, that increase its surface area for efficient absorption of nutrients into the bloodstream. Choice A is incorrect because the small intestine does not primarily secrete digestive enzymes; that role is mainly carried out by the pancreas and other digestive organs. Choice C is incorrect because the small intestine primarily absorbs nutrients rather than breaking down food. Choice D is incorrect because the absorption of water primarily occurs in the large intestine, not the small intestine.

Correct Answer: C

Rationale: The main function of the adrenal glands is to produce hormones like adrenaline and cortisol. These hormones play a crucial role in regulating blood pressure, metabolism, and the body's stress response. While the adrenal glands do have some impact on metabolism, their primary function is not the direct regulation of metabolism. They are not involved in the production of bile or insulin. Therefore, the correct answer is the regulation of blood pressure.

Correct Answer: C

Rationale: The correct answer is C: Kidneys. The kidneys are the organs responsible for filtering and cleaning the blood. They remove waste products, regulate electrolyte levels, and help maintain fluid balance in the body through the production of urine. The other choices are incorrect because: A) Lungs are primarily responsible for gas exchange, not blood filtration. B) The heart is responsible for pumping blood, not filtering it. D) The liver plays a role in detoxification and metabolism, but it is not primarily responsible for filtering and cleaning the blood.