Biochemical Endocrinology, MBMB2234: Neurochemistry

** **Examination 2021/2022****Bachelor of Medicine and Bachelor of Surgery****Paper C** **Unit Code:** MBMB2200**Unit Title:** Medical Biochemistry II(MBMB2212: Biochemical Endocrinology, MBMB2234: Neurochemistry) **Date:** Fri 28th Jan, 2022**Time:** 2.00 PM – 4.00 PM (2 Hours)**Department of Medical Biochemistry, Medical School** --- **1. All of the following are substrates and products of the reaction catalyzed by phosphatidylinositol 3-kinase EXCEPT:**A) Phosphatidylinositol bisphosphate is a substrate B) Inositol trisphosphate is a substrate C) ATP is a substrate D) Phosphatidylinositol trisphosphate is a product E) ADP is a product**Answer: B) Inositol trisphosphate is a substrate***Explanation: PI3K phosphorylates phosphatidylinositol bisphosphate (PIP2) to generate PIP3 using ATP. Inositol trisphosphate (IP3) is not a substrate; it is generated by PLC, not PI3K.* --- **2. The major difference between hormones with intracellular receptors and those with cell membrane receptors is that the former tend to be:**A) Larger B) Charged C) Amino acid derivatives D) Proteins E) Hydrophobic**Answer: E) Hydrophobic***Explanation: Hormones with intracellular receptors (e.g., steroids, thyroid hormones) are hydrophobic and can cross cell membranes.* --- **3. Many hormones like insulin, glucagon, and epinephrine:**A) Can only regulate key enzymes in metabolic pathways B) Can only regulate transcription factors C) Can regulate key enzymes and transcription factors D) Only regulate amino acid synthesis pathways E) All of the above**Answer: C) Can regulate key enzymes and transcription factors***Explanation: These hormones regulate metabolism both at enzymatic levels and through gene expression changes.* --- **4. Which hormone fits this description? "Affects metabolism, essential for CNS development, bone growth, and stored extracellularly."**A) Cortisol B) Growth hormone C) T4/T3 D) Thyrocalcitonin E) Leptin**Answer: C) T4/T3***Explanation: Thyroid hormones (T4/T3) influence metabolism, CNS maturation, and bone development; T4 is stored in the thyroid colloid.* --- **5. Calcium/Phosphate levels in blood are regulated by:**A) Aldosterone B) Cortisol C) Prolactin D) ACTH E) PTH and Calcitonin**Answer: E) PTH and Calcitonin***Explanation: Parathyroid hormone (PTH) increases blood calcium; calcitonin reduces it.* --- **6. Glucocorticoids are produced in the:**A) Adenohypophysis B) Neurohypophysis C) Pancreas D) Testes/ovaries E) None of the above**Answer: E) None of the above***Explanation: Glucocorticoids are produced in the adrenal cortex (specifically the zona fasciculata).* --- **7. The hormone primarily responsible for glucose storage as glycogen, fat storage, and protein synthesis is:**A) Glucagon B) GHC) TSH D) Insulin E) Cortisol**Answer: D) Insulin***Explanation: Insulin promotes anabolic processes such as glycogenesis, lipogenesis, and protein synthesis.* --- **8. Cyclic AMP is best matched with:**A) Steroid hormones B) Protein hormones C) Muscle cells D) Testosterone E) None of the above**Answer: B) Protein hormones***Explanation: Many protein hormones signal via cAMP second messenger (e.g., glucagon, ACTH).* --- **9. Classical endocrine glands (e.g., pituitary, thyroid):**A) Have ducts B) Are under-regulated C) Produce many products D) Produce hormones E) Use products locally**Answer: D) Produce hormones***Explanation: Endocrine glands are ductless and release hormones into circulation.* --- **10. Iodine uptake and thyroid growth are stimulated by:**A) TSH-RH B) TSH C) T3D) Thyroglobulin E) LH**Answer: B) TSH***Explanation: Thyroid-stimulating hormone (TSH) increases iodine uptake and thyroid cell proliferation.* --- **11. The primary effect of T3 and T4 is to:**A) Decrease blood glucose B) Promote calcitonin release C) Promote heat-generating (metabolic) reactions D) Stimulate iodine uptake by the thyroid E) All of the above**Answer: C) Promote heat-generating (metabolic) reactions** --- **12. The primary effect of calcitonin is to:**A) Increase blood glucose B) Decrease blood glucose C) Increase calcium excretion in urine D) Increase blood calcium E) Decrease blood calcium (blocks bone release)**Answer: E) Decrease blood calcium (blocks bone release)** --- **13. Increased blood glucose and anti-inflammatory effects are key actions of:**A) Epinephrine B) Glucagon C) Cortisol D) Insulin E) ADH**Answer: C) Cortisol** --- **14. The primary target of glucagon is the:**A) Liver B) Hypothalamus C) Adrenal cortex D) Pancreas E) Kidney**Answer: A) Liver** --- **15. The endocrine portion of the pancreas is the:**A) Adrenal cortex B) Adrenal medulla C) Anterior pituitary D) Posterior pituitary E) Islets of Langerhans**Answer: E) Islets of Langerhans** --- **16. When a hormone uses a second messenger, the next