Week 9 — Quiz (auto-graded) · The Cell Cycle & Mitosis

Course: Introduction to Biology — General Biology I (BIOL 101) · Silver Oak University (fictional sample) · Prof. Castellano
Objective tested: Objective 5 — the cell cycle (interphase G1/S/G2 + M phase); the phases of mitosis in order (PMAT) & cytokinesis; chromosome vs. chromatid; the purpose of mitosis; cell-cycle control & cancer; the mitotic index.
Points: 10 (1 each) · Assignment group: Quizzes (10% of grade) · Due: end of Module 9.

This is the human-readable quiz with its vetted answer key and feedback. The import-ready Classic QTI is in F-quiz-week-09-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.

Blueprint

No trick questions; distractors target the Week 9 misconceptions named in the lecture outline (mitosis vs. meiosis, chromosome vs. chromatid, phase order, "mitosis = the whole cycle," computing the index off the wrong total).

Questions, key, and feedback

Q1 (MC). During which stage of the cell cycle is a cell's DNA copied (replicated)?
- A. G1 phase
- B. S phase (synthesis) ✅
- C. G2 phase
- D. Anaphase
Feedback: DNA is replicated during the S phase (synthesis) of interphase — before mitosis begins. After S, each chromosome consists of two identical sister chromatids. (G1 and G2 are growth/prep stages; anaphase is when already-copied chromatids separate.)

Q2 (MC). Which statement about mitosis is correct?
- A. Mitosis is the entire cell cycle, from one division to the next.
- B. Mitosis is the division of the nucleus and chromosomes — only part of the M phase, which comes after interphase ✅
- C. Mitosis is the stage in which DNA is copied.
- D. Mitosis produces sex cells (eggs and sperm).
Feedback: Mitosis is only the division part of the M phase. All of interphase (G1, S, G2) — most of the cycle — comes first. DNA is copied in S phase (A and C are wrong), and gametes come from meiosis, not mitosis (D).

Q3 (Matching). Put the four phases of mitosis in their correct order by matching each phase to its position (1st through 4th). (Mnemonic: PMAT.)
| Phase | Correct position |
|---|---|
| Prophase | 1st (first) |
| Metaphase | 2nd (second) |
| Anaphase | 3rd (third) |
| Telophase | 4th (fourth) |
Feedback: The order is Prophase → Metaphase → Anaphase → Telophase (PMAT). Chromosomes must condense (prophase) before they can line up (metaphase), and line up before they can be pulled apart (anaphase); then two nuclei re-form (telophase).

Q4 (MC). After S phase, a duplicated chromosome is shaped like an "X." The two identical halves of that X are called sister chromatids, and they are joined at a point called the —
- A. spindle fiber
- B. centromere ✅
- C. metaphase plate
- D. cleavage furrow
Feedback: The two sister chromatids are held together at the centromere until they separate in anaphase. (Spindle fibers pull the chromatids; the metaphase plate is where chromosomes line up; the cleavage furrow pinches an animal cell in two during cytokinesis.)

Q5 (Multiple answer — select all that apply). Which of the following are true of the two cells produced by mitosis?
- A. There are two daughter cells ✅
- B. There are four daughter cells
- C. They are genetically identical to the parent cell ✅
- D. They have the same chromosome number as the parent (diploid → diploid) ✅
- E. They are gametes (eggs or sperm) with half the chromosome number
Feedback: Mitosis makes two genetically identical diploid daughter cells (A, C, D). Four different haploid cells, and gametes (B, E), are the products of meiosis — the classic mix-up this week guards against. "Mitosis makes two; meiosis makes four."

Q6 (MC). In an onion root tip, a student counts 100 cells: 80 in interphase, and 20 spread across prophase, metaphase, anaphase, and telophase. The mitotic index (the percentage of cells in mitosis) is —
- A. 80%
- B. 20% ✅
- C. 100%
- D. 4%
Feedback: Mitotic index = (cells in mitosis ÷ total cells) × 100 = (20 ÷ 100) × 100 = 20%. The 80 interphase cells are not in mitosis (so 80% is the interphase fraction, A); 4% (D) is only the metaphase count. About 1 in 5 cells is dividing.

Q7 (MC). In a healthy onion root tip, most of the cells you count are in which part of the cell cycle?
- A. Interphase ✅
- B. Metaphase
- C. Anaphase
- D. Telophase
Feedback: Cells spend most of their lives in interphase (G1, S, G2), so the large majority of cells in any snapshot are in interphase — in the model count, 80 of 100. Only a minority are caught in the brief mitotic phases.

Q8 (True / False). "Mitosis produces four genetically different daughter cells, each with half the parent's chromosome number."
- True
- False ✅
Feedback: False — that describes meiosis. Mitosis produces two genetically identical diploid cells with the same chromosome number as the parent. Mixing these up is the single most common Week-9 error.

Q9 (Matching). Match each phase of mitosis to its defining event.
| Phase | Defining event |
|---|---|
| Prophase | Chromosomes condense and the spindle begins to form |
| Metaphase | Chromosomes line up single-file across the middle of the cell |
| Anaphase | Sister chromatids separate and move to opposite poles |
| Telophase | Two new nuclear envelopes re-form around the chromosomes |
Feedback: The memory cues: Prophase = condense; Metaphase = Middle (the metaphase plate); Anaphase = Apart (chromatids separate); Telophase = Two nuclei re-form. Cytokinesis (the cytoplasm splitting) follows.

Q10 (MC). At an overview level, cancer is best described as —
- A. a brand-new kind of cell division unrelated to mitosis
- B. cells dividing in an uncontrolled way because cell-cycle checkpoints have failed ✅
- C. cells that have permanently stopped dividing
- D. the normal halving of chromosome number during division
Feedback: Cancer is uncontrolled mitosis — mutations break the checkpoints that normally stop a cell from dividing when it shouldn't, so the cell keeps dividing and forms a growing mass. It's not a new process (A) or stopped division (C); halving the chromosome number (D) is meiosis. This is also why chemo drugs that target dividing cells hit tumors — and fast-dividing hair follicles.

Answer key (quick reference)

Quality gate (self-checked): each single-answer item has exactly one correct option; the multiple-answer item (Q5) lists the three true statements (A, C, D) and requires B and E to be left unselected; the two matching items pair four phases to four distinct, correct targets (order in Q3; defining event in Q9); no item asserts a fact outside the Week 9 course definitions. This is a quantitative week (mitotic index): every number was pre-computed and independently re-verified by a Python script in the scratchpad that re-derived the mitotic index (20 of 100 → 20%), the interphase fraction (80% → 19.2 h of a 24-h cycle), and the phase-count sum (80+9+4+3+4 = 100) and printed PASS — quantitative gate: PASS.

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

All ten items are tagged course=BIOL101 · week=9 · objective=5 · topic=cell-cycle-and-mitosis and deposited in Item Bank: Week 9 — The Cell Cycle & Mitosis. The final (Week 16) and the per-term variant updates draw fresh items from this bank. (Tags: q1 s-phase-dna, q2 mitosis-is-not-whole-cycle, q3 pmat-order-match, q4 chromosome-vs-chromatid, q5 products-of-mitosis, q6 mitotic-index-calc, q7 most-cells-interphase, q8 mitosis-vs-meiosis-tf, q9 phase-to-event-match, q10 cancer-uncontrolled-division.)

Canvas placement block

canvas_object   = Quizzes::Quiz
title           = "Week 9 Quiz — The Cell Cycle & Mitosis"
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. Castellano's edition · Fall 2026 · built with thecoursemaker.com"