Week 12 — Quiz (auto-graded) · Nervous Tissue, the Neuron & the Action Potential

Course: Anatomy & Physiology I (BIOL 2301 + BIOL 2101) · Silver Oak University (fictional sample) · Prof. Navarro
Objective tested: Objective 6 — neuron structure & neuroglia; the resting membrane potential & the Na⁺/K⁺ pump; the action potential as an ordered sequence of ion movements; myelin & conduction; synaptic transmission.
Points: 10 (1 each) · Assignment group: Quizzes (10% of grade) · Due: end of Module 12.

This is the human-readable quiz with its vetted answer key and feedback. The import-ready Classic QTI is in F-quiz-week-12-qti.xml (generated by the shared validated script — parses with 10 items, every single-answer item exactly one correct). The reusable item-bank entries and the Canvas placement block are at the bottom of this file. (QTI text uses plain ASCII — "-70 mV", "Na+", "K+", "to" — for clean import.)

Blueprint

No trick questions; distractors target the Week 12 misconceptions named in the lecture outline.

Questions, key, and feedback

Q1 (Matching). Match each part of a neuron to its main function.
| Part | Correct function |
|---|---|
| Dendrites | Receive incoming signals from other neurons |
| Axon | Conducts the impulse away from the cell body |
| Myelin sheath | Insulates the axon and speeds conduction |
| Cell body (soma) | Contains the nucleus and integrates inputs |
Feedback: Information flows in the dendrites → across the soma → out the axon. Dendrites receive; the soma (with the nucleus) integrates and decides; the axon conducts the impulse away; myelin insulates the axon and speeds conduction. (Dendrites = inbox, soma = decision, axon = outgoing cable.)

Q2 (MC). The resting membrane potential of a typical neuron is about −70 mV. What does this tell you about the charge inside the cell at rest?
- A. The inside is positive relative to the outside
- B. The inside is negative relative to the outside ✅
- C. The inside and outside have exactly equal charge
- D. The membrane carries no electrical charge at rest
Feedback: The minus sign is the point: at rest the inside is negative (about −70 mV) relative to the outside. The inside only becomes positive briefly, during depolarization. (A is the classic error; C/D ignore the resting potential entirely.)

Q3 (Matching — sequence/ordering). An action potential moves through its phases in a fixed order. Match each step number to the correct phase (1 = first, 4 = last).
| Step | Correct phase |
|---|---|
| Step 1 (start) | Resting potential (about −70 mV) |
| Step 2 | Depolarization (Na⁺ rushes in; inside becomes positive) |
| Step 3 | Repolarization (K⁺ flows out; inside becomes negative again) |
| Step 4 (end before return to rest) | Hyperpolarization (brief dip below −70 mV) |
Feedback: The order never changes: resting → depolarization → repolarization → hyperpolarization → back to rest. Depolarization (Na⁺ in) makes the inside positive; repolarization (K⁺ out) brings it back down; hyperpolarization is a brief overshoot below −70 mV. Sodium in to fire, potassium out to reset.

Q4 (MC). During the depolarization phase of the action potential, which ion movement makes the inside of the neuron become positive?
- A. Sodium (Na⁺) rushing INTO the cell ✅
- B. Potassium (K⁺) flowing OUT of the cell
- C. Chloride (Cl⁻) rushing INTO the cell
- D. Calcium (Ca²⁺) being pumped OUT of the cell
Feedback: Depolarization = Na⁺ IN. At threshold (≈ −55 mV), voltage-gated sodium channels open and positive Na⁺ floods in, flipping the inside positive (peak ≈ +30 mV). (B is repolarization; the classic error is swapping these two.)

Q5 (MC). Repolarization returns the inside of the neuron toward negative. It happens when —
- A. sodium (Na⁺) channels open and Na⁺ flows in
- B. potassium (K⁺) channels open and K⁺ flows out ✅
- C. the membrane stops conducting entirely
- D. calcium (Ca²⁺) floods in from the synapse
Feedback: Repolarization = K⁺ OUT. Sodium channels close, potassium channels open, and positive K⁺ leaves the cell, pulling the inside back toward negative. (A is depolarization; C/D don't describe repolarization.)

Q6 (MC). The sodium–potassium pump helps maintain the resting potential. For each ATP it uses, the pump moves —
- A. 3 sodium (Na⁺) IN and 2 potassium (K⁺) OUT
- B. 2 sodium (Na⁺) IN and 3 potassium (K⁺) OUT
- C. 3 sodium (Na⁺) OUT and 2 potassium (K⁺) IN ✅
- D. 2 sodium (Na⁺) OUT and 2 potassium (K⁺) IN
Feedback: The pump moves 3 Na⁺ OUT and 2 K⁺ IN per ATP, restoring the resting gradients (Na⁺ belongs outside, K⁺ inside). Moving 3 positives out for 2 in also helps keep the inside slightly negative. (A reverses the directions — the most common slip.)

Q7 (MC). Multiple sclerosis damages the myelin sheath around axons. Based on what myelin does, this damage would —
- A. speed up nerve conduction
- B. slow down or block nerve conduction ✅
- C. have no effect on nerve signals
- D. make the resting potential more positive
Feedback: Myelin speeds conduction (the signal jumps node to node — saltatory conduction). Destroy the insulation and signals slow, scatter, or fail — the structure→function logic behind MS symptoms (weakness, numbness, vision and coordination problems).

Q8 (True / False). "At rest, the inside of a neuron is positive relative to the outside."
- True
- False ✅
Feedback: False. At rest the inside is negative, about −70 mV. It only becomes positive briefly, during depolarization, when Na⁺ rushes in. Watch the minus sign — this is the single most common error of the week.

Q9 (Multiple answer — select all that apply). Which of the following statements about the action potential are TRUE?
- A. It follows the all-or-none principle (it fires fully or not at all) ✅
- B. Threshold is reached at about −55 mV ✅
- C. During depolarization, Na⁺ moves INTO the cell ✅
- D. During depolarization, K⁺ moves INTO the cell
- E. The resting potential is about +70 mV
Feedback: True: the AP is all-or-none (A); threshold ≈ −55 mV (B); depolarization is Na⁺ IN (C). False distractors: K⁺ does not move in during depolarization (D) — K⁺ moves out during repolarization; and the resting potential is −70 mV, not +70 (E).

Q10 (MC). How does a signal cross the synapse from one neuron to the next?
- A. The action potential jumps the gap as a spark of electricity
- B. Neurotransmitters are released and diffuse across the synaptic cleft to bind receptors on the next neuron ✅
- C. The two neurons fuse so the cytoplasm mixes
- D. Myelin carries the chemical message across the cleft
Feedback: At a chemical synapse, the arriving impulse triggers Ca²⁺ entry → neurotransmitter release into the synaptic cleft → the chemical binds receptors on the next neuron. The signal goes electrical → chemical → electrical; it does not spark across (A), the cells stay separate (C), and myelin isn't involved at the cleft (D).

Answer key (quick reference)

Quality gate (self-checked): each single-answer item has exactly one correct option; the multiple-answer item (Q9) marks exactly A, B, C correct and requires D ("K⁺ in during depolarization") and E ("resting +70") to be left unselected; the two matching items pair four items to four distinct targets, and Q3 is the sequence/ordering item (the AP phases). Every anatomical fact is verified against standard A&P (OpenStax §§12.2, 12.4; InnerBody Nervous System): neuron parts→function, the six neuroglia, the Na⁺/K⁺ pump direction (3 out, 2 in), the ordered phases (rest → depol = Na⁺ IN → repol = K⁺ OUT → hyperpol), and synaptic transmission. Anatomy-accuracy gate: PASS. Every numeric value is pre-computed and re-verified in Python (/tmp/w12_check.py): resting −70 mV, threshold −55 mV, peak +30 mV; −70 to −55 = 15 mV to threshold; −70 to +30 = 100 mV swing; pump 3 Na⁺ out / 2 K⁺ in. All values used consistently across every Week-12 file; overview-level only (no Nernst). Quantitative gate: PASS.

Item-bank entries (for variants + the midterm/final)

All ten items are tagged course=BIOL2301 · week=12 · objective=6 · topic=neuron-action-potential and deposited in Item Bank: Week 12 — Nervous Tissue & the Action Potential. The final (Week 16) and the per-term variant updates draw fresh items from this bank. (Tags: q1 neuron-parts-match, q2 resting-potential, q3 ap-phase-order, q4 depolarization-na-in, q5 repolarization-k-out, q6 na-k-pump, q7 myelin-conduction, q8 resting-negative-tf, q9 ap-true-statements, q10 synaptic-transmission.)

Canvas placement block

canvas_object   = Quizzes::Quiz
title           = "Week 12 Quiz — Nervous Tissue, the Neuron & the Action Potential"
assignment_group = "Quizzes"
points_possible = 10
grading_type    = points
due_offset_days = 6        # 6 days after module start
published       = true
shuffle_answers = true
provenance      = "~ Prof. Navarro's edition · Fall 2026 · built with thecoursemaker.com"