Which is a water soluble vitamin?

Correct Answer: B

Rationale: The correct answer is B: B12. Vitamin B12 is water-soluble because it dissolves in water, allowing it to be easily absorbed and transported in the bloodstream. It plays a crucial role in nerve function, red blood cell production, and DNA synthesis. Vitamins D, A, and K are fat-soluble vitamins, meaning they are absorbed along with fats in the diet and are stored in the body's fat tissues. Since they are not water-soluble, they require bile for absorption and are stored in the body for longer periods. Hence, B12 is the only water-soluble vitamin among the given choices.

Correct Answer: B

Rationale: Chief cells in the stomach secrete pepsinogen, which is the inactive precursor of pepsin, an enzyme that helps break down proteins. This is the correct answer because pepsinogen is the primary product secreted by chief cells. HCl is secreted by parietal cells, intrinsic factor is secreted by parietal cells in the stomach, and HCO3- is secreted by the pancreas to neutralize stomach acid in the duodenum.

Correct Answer: D

Rationale: Step-by-step rationale for choice D being correct: 1. ATP is an energy carrier molecule. 2. Adenosine triphosphate (ATP) is a precursor of cyclic AMP. 3. Cyclic AMP is a secondary messenger involved in cellular signaling. 4. Therefore, choice D is true. Summary of incorrect choices: A: Adenosine triphosphate is a high-energy phosphate, not low. B: Reduction involves gain, not loss, of electrons. C: Oxidative phosphorylation occurs in the mitochondria, not the endoplasmic reticulum.

Correct Answer: B

Rationale: The correct answer is B because antidiuretic hormone (ADH) actually causes urine volume to decrease as blood volume decreases, not increase. ADH acts on the kidneys to reabsorb water, leading to concentrated urine and conservation of body fluids. Rationale summary: A: True, hyposecretion of FSH or LH can lead to sterility in both males and females. C: False, oxytocin is also released during sexual activity, breastfeeding, social bonding, and stress responses, not just during childbirth and nursing. D: True, luteinizing hormone triggers ovulation and stimulates the production of progesterone and some estrogens.

Correct Answer: D

Rationale: The correct answer is D: insulin. Elderly individuals are more likely to develop type 2 diabetes due to a decrease in insulin production by the pancreas and decreased sensitivity to insulin in tissues. Insulin plays a crucial role in regulating blood sugar levels by facilitating the uptake of glucose into cells for energy production. A decline in insulin production or sensitivity can lead to elevated blood sugar levels, contributing to the development of type 2 diabetes. Estrogen (choice A), thyroid hormone (choice B), and follicle-stimulating hormone (choice C) do not directly impact insulin production or sensitivity in the context of type 2 diabetes development in elderly individuals.