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Neuron Function Worksheet With Complete Solution 2026
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what is the job of a neuron - Correct Answer-to move an electrical signal from one place to another in order to send sensory messages throughout the body Which of the gated embedded proteins in Model 1 allow sodium ions ( O ) through the membrane? - Correct Answer-gates A, B, D and F allow sodium ions through the membrane Which of the gated embedded proteins in Model 1 allow potassium ions ( triangles ) through the membrane? - Correct Answer-Gates C, E, and G allow potassium ions through the membrane The neuron illustrated in Model 1 has received a signal from either a sensory cell (taste bud, skin cell, retinal cell, etc.) or from another neuron. What evidence do you find in diagram 1 of the model that indicates a signal has been received? - Correct Answer-A signal Ligand has bound to the ligand-gated embedded protein and the gate has opened In diagram 2 of Model 1, gated embedded protein B has opened. Was this opening triggered by the arrival of a signal ligand? If no, propose an alternate stimulus that might have triggered the gate to open. - Correct Answer-No, diagram 2 does not show a ligand bound to embedded protein B. The gate may have opened because of the change in membrane potential from the flood of ions nearby When a signal moves down the axon of the neuron, which direction do sodium ions move through the voltage-gated embedded proteins? - Correct Answer-sodium ions move into the cell when the sodium gates are opened What does the movement of sodium ions across the membrane do to the membrane potential near the open embedded protein? - Correct Answer-the membrane potential increases (gets more positive) as the sodium ions move into the cell When a signal moves through the axon of the neuron, which direction do potassium ions
move through the voltage-gated embedded proteins? - Correct Answer-potassium ions move out of the cell when the potassium gates are opened What does the movement of potassium ions across the membrane do to the membrane potential near the open embedded protein? - Correct Answer-the membrane potential decreases ( gets more negative) as the potassium ions move out of the cell when a neuron is resting the cell membrane is said to be POLARIZED - Correct Answer- how is the degree of polarization measured? - Correct Answer-the degree of polarization is measured by the cell membrane potential the gated embedded proteins in the axon of a neuron are triggered to open by changes in electrical potential across the membrane. - Correct Answer-the voltage at which they open is called the threshold potential Looking at model 1 What is the threshold potential that causes the sodium ion gates to open? - Correct Answer-the sodium ion gates open at -55 mV Looking at model 1 At what potential are the potassium ion gates fully open? - Correct Answer-the potassium ion gate open at +35 mV looking at model 1 at what potential are the sodium ion gates closed - Correct Answer-the sodium ion gates close when the membrane potential reaches +35 mV At what potential are the potassium ion gates closed? - Correct Answer-The potassium ion gates close when the membrane potential reaches -80 mV Describe how the electrical signal in the neuron moves - Correct Answer-the gates open one at a time from left to right in model 1. the high concentration of sodium ions inside the cell moves from left to right in model 1 A. When the gated embedded proteins (either sodium or potassium) close, do the sodium and potassium ions remain on the side of the membrane that they are on, or do they move back to their original position? - Correct Answer-The sodium and potassium ions eventually move back to their original position
of a minimum signal to fire off an impulse saves resources to react to sensory information that is vital for survival. One student described the diagrams in Model 1 by saying "As more gates open the concentration of sodium inside the cell increases and this causes even more gates to open." Is this an example of a positive or negative feedback loop? - Correct Answer-This is a positive feedback because the end result of the process makes the process happen again and escalates the response. The response, opening of gated embedded proteins, amplifies the stimulus, a change in cell membrane potential. For a neuron to function, an input of free energy from ATP is required to set up the sodium and potassium ion concentration gradients such that a signal can be propagated down the axon of a neuron without the necessity of ATP. The system could have worked the opposite way. The neuron could have used ATP to move ions across when a signal was being propagated and then allow natural diffusion to return the ions to their respective sides of the membrane. What advantage does the organism have using ATP up front? - Correct Answer-During times of stress, such as running from a predator, a lack of ATP would slow the nerve response if it was required to create the action potential. In the current form the ATP is needed slowly during rest periods and the natural flow of ions used when quick response is necessary.