31. If the potassium leak channels are blocked, what will happen to the membrane

Question

31. If the potassium leak channels are blocked, what will happen to the membrane potential? (a) The interior of the cell will become less negative (b) The interior of the cell becomes less positive (c) The exterior of the cell becomes less negative (d) The exterior of the cell becomes less positive 32. What would happen to the membrane potential if sodium ions were allowed to flow down their concentration (a) The interior of the cell will become less negative (b) The interior of the cell becomes l ess positive (c) The exterior of the cell becomes less negative r of the cell becomes more positive (d) The exterio 33. How can a presynaptic neuron increase the intensity of the signal it is transmitting? (a) Increase the amount of neurotransmitters secreted (b) Change the type of neurotransmitter released (c) Increase the frequency of the action potential (d) Initiate a passive spread signal 34. What is the effect of opening the voltage gated sodium channels on the membrane potential? (a) Makes the interior of the cell less negatively charged (b) Makes the interior of the cell more negatively charged (c) Makes the interior of the membrane less positive (d) None of the above 35. When an action potential starts at one end of an axon, can it run out of energy and not reach the other end? (a) Yes (b) No 36. The sodium-potassium pump establishes concentration gradients: (a) Of higher sodium concentrations inside the cell and higher potassium concentrations outside the cell (b) Of sodium and potassium but the area of their concentrations (inside or outside) depends on the needs of the cell (c) Of higher potassium concentrations inside the cell and higher sodium concentrations outside the cel (d) By pumping sodium outside the cell and potassium is cotransported out as well 37. ATP is required in the transport of (a) All molecules across a membrane (b) Molecules through a protein channel (c) Molecules to areas of lower concentrations (d) Molecules to areas of higher concentrations 38. The net movement of uncharged, polar molecules across a semipermeable membrane from a low concentration to a high concentration occurs by diffusiorn (a) True (b) False 39. Fluidity of phospholipid bilayer is increased by (a) Cholesterol at certain temperatures (b) Double bonds between carbon atoms in the fatty acid tails (c) Shorter hydrophobic tails (d) All the above 40. All the following statements concerning transmitter-gated ion channels are true EXCEPT (a) Are Ligand-gated channels (b) Are Voltage-gated channels (c) Convert the chemical signal neurotransmitter into an electrical signal (d) Are receptors

Explanation / Answer

31. Answer A

At resting membrane potential pottasium is present inside the cell. Sodium and cholride are present outside the cell.when potassium channels are blocked exchange of ions according to their concentration is not possible and chloride remain outside the cell and inside cell becomes less negitive charge build up is seen.

32. C

Sodium ions move inside the cell along with choloride ion according to their concentration. As the chloride moves inside less negitivity is produced outside.

33.A

To increase ignal transmission more numbnumber oof neurotransmitter are requiredbeacusrequiredbeacuse nuerotrnsmitors are responsible for signal transmission at synaptic cleft.

34. D

Sodium influx increase postivity of the cell beacuse potassium ion concentration is more inside the cell so along with potassium and sodium the cell postivity increases inside.

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