BIO HOMEWORK

1. How does the sodium-potassium pump contribute to the resting potential of a neuron?

• A) It pumps Na+ into the neuron and K+ out
  

• B) It pumps Na+ out and K+ in, maintaining a negative charge inside
  

• C) It allows passive diffusion of ions
  

• D) It only functions during an action potential

2. Why is the inside of a neuron negatively charged at rest?

• A) There are more negatively charged ions inside than outside
  

• B) The sodium-potassium pump removes more positive ions than it brings in
  

• C) Large negatively charged proteins remain inside the cell
  

• D) All of the above

3. What is the typical resting membrane potential of a neuron?

• A) +30 mV
  

• B) 0 mV
  

• C) -70 mV
  

• D) -55 mV

4. What triggers depolarization in a neuron?

• A) The opening of voltage-gated sodium (Na+) channels
  

• B) The closing of potassium (K+) channels
  

• C) The release of neurotransmitters
  

• D) The activity of the sodium-potassium pump

5. What happens during repolarization?

• A) Sodium channels open, and Na+ enters the cell
  

• B) Potassium channels open, allowing K+ to leave the cell
  

• C) The neuron becomes more positive inside
  

• D) The neuron reaches the threshold potential

6. What is the threshold potential?

• A) The voltage at which an action potential is triggered
  

• B) The maximum voltage a neuron can reach
  

• C) The voltage at which neurotransmitters are released
  

• D) The resting membrane potential

Answer explanation

(Usually around -55 mV.)

7. What occurs at the synaptic cleft during chemical synaptic transmission?

• A) Electrical signals jump across the gap
  

• B) Neurotransmitters are released and bind to receptors on the postsynaptic neuron
  

• C) Ions flow directly between neurons through gap junctions
  

• D) The action potential stops before reaching the cleft

8. What causes neurotransmitter release into the synaptic cleft?

• A) The influx of sodium ions
  

• B) The opening of voltage-gated calcium (Ca²⁺) channels
  

• C) The sodium-potassium pump
  

• D) The movement of potassium ions out of the neuron

9. What happens to neurotransmitters after they bind to the postsynaptic receptors?

• A) They remain in the synaptic cleft indefinitely
  

• B) They are broken down by enzymes or reabsorbed by the presynaptic neuron
  

• C) They continue stimulating the postsynaptic neuron indefinitely
  

• D) They diffuse into the bloodstream

10. Why is the sodium-potassium pump important for neuron function?

• A) It generates action potentials
  

• B) It restores ion balance after an action potential
  

• C) It directly releases neurotransmitters
  

• D) It depolarizes the neuron