Biology Exam Question Paper and Answers -1
1. Which of the following serves as a sensor, or as part of a sensor, that functions in a negative feedback system?
A. Mechanically-gated channels located in the plasma membranes of the peripheral axon terminals of carotid artery baroreceptor neurons.
B. Osmoreceptor neurons whose peripheral terminals are located in the walls of the carotid artery.
C. Calcium-Sensing Receptors (CaSRs) located in the plasma membranes of Parathyroid Gland cells.
D. A and B.
E. A and C.
F. B and C.
G. A, B, and C.
H. None of the above.
2. Which of the following serves as an actuating signal, or as part of an actuating signal, in a negative feedback system?
A. Blood plasma levels of oxytocin.
B. Blood plasma levels of glucagon.
C. Blood plasma levels of Vasopressin Releasing Hormone (VRH).
D. A and B.
E. A and C.
F. B and C.
G. A, B, and C.
H. None of the above.
3. Which of the following serves as an effector, or as part of an effector, in a negative feedback system?
A. GLUT2 molecules in the plasma membranes of liver cells.
B. Binding sites for calcium ions on tropomyosin molecules in rib cage inspiratory muscles.
C. Glycogen Receptors in the plasma membranes of liver cells.
D. A and B.
E. A and C.
F. B and C.
G. A, B, and C.
H. None of the above.
4. Which of the following serves as a controlled variable in a negative feedback system?
A. Blood plasma levels of glucagon.
B. Blood plasma levels of glucose.
C. Blood plasma levels of calcium.
D. A and B.
E. A and C.
F. B and C.
G. A, B, and C.
H. None of the above.
5. A new drug named AGON-CaSR has been developed that is an agonist atcalcium-binding sites of CaSRs (Calcium-Sensing Receptors) in plasma membranes ofparathyroid gland cells. Healthy Person P receives regular doses of AGON-CaSR aspart of a clinical trial. When AGON-CaSR levels in the extracellular spaces surroundingparathyroid gland cells increase in Healthy Person P, this leads to
A. an increase in the levels of calcium in the blood plasma.
B. an increase in the levels of parathyroid hormone (PTH) in the blood plasma.
C. a decrease in the plasma levels of 1,25-dihydroxyvitamin D.
D. A and B.
E. A and C.
F. B and C.
G. A, B, and C.
H. None of the above.
6. Which of the following substances serve as ligands that bind to intracellular receptors that are located in the nucleus?
A. Growth Hormone (GH).
B. 1,25 dihydroxyvitamin D.
C. Insulin.
D. A and B.
E. A and C.
F. B and C.
G. A, B, and C.
H. None of the above.
7. Which of the following is true?
A. GLUT2 molecules are responsible for the net flux of glucose from the luminalspaces of the kidney cortex into the intracellular spaces of proximal tubuleepithelial cells.
B. When blood plasma levels of glucagon are low and blood plasma levels of insulinare high, GLUT2 molecules are responsible for the net flux of glucose from theintracellular spaces of liver cells into the interstitial spaces surrounding liver cells.
C. GLUT4 molecules are responsible for the net flux of glucose from the interstitialspaces surrounding beta-islet cells of the pancreas into the intracellular spacesof beta-islet cells of the pancreas.
D. A and B.
E. A and C.
F. B and C.
G. A, B, and C.
H. None of the above.
8. Which of the following is an effect of the following drugs?
A. Drug A is an agonist of the Vasopressin2 Receptor (V2R). High levels of Drug Ain the interstitial spaces surrounding cells of the kidney medullary collecting ductswill lead to high levels of exocytosis of AQP2 molecules in these cells.
B. Drug B is an agonist of the Insulin Receptor. High levels of Drug B in theinterstitial spaces surrounding fat cells will lead to high levels of exocytosis ofGLUT4 transporters in these cells.
C. Drug C is an agonist of the Glucagon Receptor. High levels of Drug C in theinterstitial spaces surrounding liver cells will lead to high levels of exocytosis ofGLUT4 transporters in these cells.
D. A and B.
E. A and C.
F. B and C.
G. A, B, and C.
H. None of the above.
9. At 1 AM, an impermeable membrane separates a 1 liter solution of 1M NaCl in the leftcompartment from a 1 liter solution containing both 1M NaCl and 1M KCl in the rightcompartment. At 2 AM, the membrane became permeable to chloride ions. At 4 AM,the membrane once again became impermeable to chloride ions. At 6 AM, themembrane became permeable to sodium ions and, in addition, maintained chloride ionimpermeability. At 8 AM, the membrane once again became impermeable to sodiumions. At 10 AM the membrane once again became permeable to chloride ions and, inaddition, maintained sodium ion impermeability. The membrane maintainedimpermeability to potassium ions during the entire period.
A. The amount of sodium ions in the left compartment at 7 AM will be greater thanthe amount of sodium ions in the left compartment at 5 AM.
B. The amount of chloride ions in the left compartment at 11 AM will be greater thanthe amount of chloride ions in the left compartment at 5 AM.
C. The amount of chloride ions in the left compartment at 11 AM will be less thanthe amount of chloride ions in the right compartment at 11 AM.
D. A and B.
E. A and C.
F. B and C.
G. A, B, and C.
H. None of the above.
10. Which of the following is true for a G-protein?
A. After the GTP-ase of the alpha subunit of a G-protein converts the GTP bound tothe alpha subunit to GDP and inorganic phosphate (Pi), the inorganic phosphate(Pi) is released from the alpha subunit. The alpha subunit of the G-protein withGDP bound to it then associates with the beta and gamma subunits of theG-protein.
B. When an agonist binds to the binding site of a G-protein-coupled receptor(GPCR), this leads to GDP displacing a GTP bound to the alpha subunit of theG-protein.
C. When ADP binds to an alpha subunit of the G-protein, this leads to the alphasubunit of the G-protein associating with the beta and gamma subunits of theG-protein.
D. A and B.
E. A and C.
F. B and C.
G. A, B, and C.
H. None of the above.
Answer
1-e , 2-b , 3-a , 4-f , 5-c , 6-b , 7-h , 8-d , 9-g , 10-a