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A comprehensive review of key concepts related to membrane potential and action potentials in biology. It includes multiple-choice questions, true/false statements, and explanations for each answer, covering topics such as resting membrane potential, depolarization, repolarization, hyperpolarization, and the role of different ions in these processes. Particularly useful for students preparing for an exam on this subject.
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Which ion has greatest influence on resting membrane potential? ✔✔Potassium (potassium has more leak channels on the membrane than sodium, which is why potassium has a higher permeability value and has more impact of resting membrane potential)
Concerning resting membrane potential, the inside of the membrane is _______ compared to the ________ charged outside. ✔✔negative, positively.
T or F:
The diffusion of K+ and Na+ down their chemical gradients contributes to the resting membrane potential ✔✔F
At resting membrane potential, ______________________. ✔✔extracellular sodium levels are high
During the hyper polarization phase... ✔✔K+ leaves the cell
Which is not a characteristic of a graded potential?
A) Spreads in a decremental fashion
B)Can result from changes in voltage across the membrane
C) Can summate
D) Size is inversely proportional to stimulus strength ✔✔D
As the stimulus strength and size of the graded potential _____________ the action potential frequency ___________. ✔✔increases; increases
The outside of a cell during resting membrane potential is _________ in relation to the inside of the cell. ✔✔Positively charged
If at resting membrane potential (RMP), the plasma membrane became more permeable to K+, the cell would _________________________. ✔✔hyperpolarize
Which ion has greatest influence on resting membrane potential? ✔✔K+
Which statement is true?
A) ATP is required to move Na+ extracellularly
If a plasma membrane becomes more permeable to K+ the charge difference across the plasma membrane will _________, or (AKA) _________. ✔✔increase, hyperpolarize
If the extra cellular fluid around a muscle cell is replaced with an isotonic saline solution that contains less K+ than the normal extra cellular fluid, the result would be: ✔✔a hyperpolarized membrane
The resting membrane potential of a cell is = -60mV, and the intracellular and extracellular Cl- concentrations are [Cl-]inside = 7 mM and [Cl-]outside = 105 mM, respectively. Which of the following statements is FALSE?
A) The Cl- electrical gradient is inward
B) The Cl- concentration gradient is inward
C) Both a and b are True statements
D) Both a and b are False statements ✔✔A
T or F:
Simple diffusion is based on the fact that molecules are in constant, random motion. Because of collisions with each other, and anything else in the particles way, they eventually disperse- or are evenly distributed throughout the system. ✔✔T
The "All-or-None" principle ✔✔whether the stimulus is just strong enough to reach threshold or if it is so strong to surpass the threshold, the action potential will proceed without stopping
Repolarization results ✔✔from the increase in potassium moving out of the cell
Refractory period ✔✔from beginningof action potential, return to resting state, during whichmembrane will not respond normally to additional stimuli
Absolute refractory period ✔✔sodium channels open or inactivated no action potential possible
Opening of sodium gates typically leads to ________. ✔✔depolarization of the plasma membrane
Action potentials are constant in ___________. (Hint: all-or-none principle) ✔✔Magnitude
Which statements are true? ✔✔-The purpose of the Na+, K+ ATPase pump is to maintain concentration gradients of Na+ and K+.
-The brain prefers to use action potentials, but can function using other forms of communication like ketones.
-If a graded potential does not hit threshold it will never become an action potential.
Which statement is true regarding ion concentrations across a resting membrane? ✔✔K+ concentration is greater intracellularly and Na+ concentration is greater extracellularly.
When a cell is in the depolarization phase... ✔✔a new action potential is possible provided the repolarization potential value is lower than threshold
How is a cell repolarized after stimulation? ✔✔by K+ flowing out of the cell
Which is true regarding voltage-gated K+ channels? ✔✔-They only have one gate.
-They are slower to open than Na+ channels. -They stay open until repolarization is complete.
-They only allow K+ ions to flow through them.
What occurs during depolarization? ✔✔There is a rapid influx of Na+ ions.
Define threshold ✔✔the critical level of depolarization that must be achieved to fire an action potential
What is an action potential? ✔✔An action potential is an electrical impulse that travels down the axon, leading to neurotransmitter release
Define membrane potential ✔✔difference in electrical charge between the inside and outside of a cell
Define resting potential ✔✔steady membrane potential of -70mV, and in this state with the - mV charge built up across its membrane it is said to be POLARIZED
less then -70 mV ✔✔DEPOLARIZED
More than -70 mV ✔✔HYPERPOLARIZED
competition
saturation
tonicity
specificity ✔✔tonicity
Small pieces of matter, and even whole cells, can be transported across the plasma membrane in ✔✔vesicles
Which is true in regard to concentration gradients? ✔✔The greater the difference between areas of high concentration and low concentration, the greater the rate of diffusion.
The rate of diffusion increases if the ✔✔viscosity of a solution decreases.