The refractory period:
1.prevents the retrograde propagation of Action Potentials along the neuronal membrane
2.prevents the retrograde propagation of Graded Potentials along the neuronal membrane
3.results from actions of the Na+/K+ pump
4.Both 1 and 3 are correct.
5.All of these are correct.
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Question 2) The depolarization (rising phase) of the Action Potential is due to:
1.the influx of K+ from the ECF to the ICF.
2.the influx of Na+ from the ECF to the ICF.
3.the influx of Na+ through leak channels.
4.the movement of Na+ and of K+ by active transport.
5.None of these is correct.
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Question 3) Graded potentials in a nerve or muscle cell membrane:
1.spread by passive current flow.
2.are local changes in membrane potential.
3.spread from the point of origin
4.Both 1 and 2 are correct.
5.All of these are correct.
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Question 4) The membrane potential in a typical cell
1.is the sum of the individual potentials of all ions.
2.is positive on the inside relative to the outside of the cell.
3.is the result of a charge difference between the inner and outer surfaces of the membrane.
4.is entirely the result of the difference in potassium ion concentrations on the two sides of the membrane.
5.is entirely the result of the difference in cation concentrations on the two sides of the membrane.
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Question 5) Which is true of vesicular transport from the cell interior across plasma membranes?
1.It requires no energy input.
2.The transported substances diffuse through membrane pores.
3.The transported substance is enclosed in a membrane-wrapped organelle that fuses with the plasma membrane.
4.It is also known as endocytosis.
5.The transported substance is attached to carrier proteins in the plasma membrane.
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Question 6) Which of the following is true of primary active transport across cell membranes?
1.Moves substances down their concentration gradients
2.Requires no energy input
3.Substances cross the membranes through pores
4.Is typically coupled to the hydrolysis of ATP.
5.None of these is correct.
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Question 7) Which of the following reduces the net rate of diffusion of substance across a membrane?
1.Increasing the molecular weight of the substance
2.Decreasing the thickness of the membrane
3.Increasing the surface area of the membrane
4.Increasing the lipid solubility of the substance
5.Increasing the concentration difference of the substance across the membrane
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Question 8) The phospholipid bilayer in plasma membranes is arranged
1.with the polar heads on the internal and external surfaces.
2.with the polar heads on the internal surfaces only.
3.with the polar heads on the external surfaces only.
4.with the polar heads in the center.
5.with the polar heads distributed randomly.
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Question 9) During each cycle of oxidative phosphorylation
1.approximately 28 ATP molecules are synthesized.
2.each molecule of glucose is broken down to form 2 molecules of pyruvate.
3.NAD+ is reduced to NADH.
4.GTP is formed, but immediately donates its phosphate to ADP to form ATP.
5.oxygen donates electrons to power the ATP synthase (molecular motor).
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Question 10) During the citric acid cycle:
1.3 molecules of ATP are synthesized per Acetyl-CoA molecule entering the process.
2.3 molecules of FADH2 are synthesized per Acetyl-CoA entering the process.
3.3 molecules of NADH are synthesized per Acetyl-CoA entering the process.
4.2 molecules of ATP are hydrolyzed in each revolution of the cycle.
5.Both 2 and 3 are correct.
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