Experiment 2: Formative Quiz

What will be the stimulus to open voltage-gated Na⁺ channels?

• Presence of Ach in the interstitium

• Presence of Ach in the cytoplasm

• A membrane potential of -35 mV

• A membrane potential of -65mV

Which of the following would be true about the Na-K pump?

• Movement of ions would be from an area of higher concentration to an area of lower concentration

• 3 Na⁺ ions would be pumped inside and 2 K⁺ ions would be pumped outside the cell

• It is an example of secondary active transport

• The stimulus for its activation would be an accumulation of Na ions inside the cell

What will you expect during skeletal muscle contraction?

• The A band will disappear

• The A band will shorten

• The Z disc will disappear

• The Z discs will approximate each other

Which subunit of the troponin complex would have a high affinity to Ca²⁺ ions?

• Troponin I

• Troponin T

• Troponin C

• Troponin A

Which of the following would be a direct effect of an increase in intracellular concentration of Ca²⁺ ions?

• A "tug" in the tropomyosin protein

• Actin filaments will move closer to each other

• Opening of ligand gates

• Formation of ATP

Which of the following would be true of an action potential?

• It can only happen in excitable cells

• Depolarization occurs as Na⁺ ions would influx the cell

• The membrane potential at which voltage-gated potassium channels open is -65 mV

• All options are correct

Which of the following is true about the refractory period?

• You would not be able to re-excite an already excited area during the absolute refractory period

• You would not be able to re-excite an already excited area during the relative refractory period

• There is rapid influx of Na⁺ ions in this phase

• All options are correct

Which of the following ions are needed to move inside the axon terminal in order for the synaptic vesicles to release its contents into the synaptic cleft?

• Cl^-

• Na⁺

• ATP

• Ca⁺⁺

What will be the effect on the membrane potential if the concentration of cations outside the membrane will be increased?

• It will be easier to stimulate an action potential

• The membrane potential will become more negative

• The membrane potential will become more positive

• There will be no effect on the membrane potential

Which of the following would affect movement of ions across a membrane?

• Electrical charge of ions

• Permeability of the membrane to the ions

• Concentration gradient of the ions inside and outside the cell

• All options are correct