Week 10 — Quiz (auto-graded) · Meiosis & Sexual Reproduction

Course: Introduction to Biology — General Biology I (BIOL 101) · Silver Oak University (fictional sample) · Prof. Castellano
Objective tested: Objective 5 — ploidy & homologous chromosomes; the stages of meiosis; crossing over & independent assortment; mitosis vs. meiosis; the 2ⁿ count of genetic variation.
Points: 10 (1 each) · Assignment group: Quizzes (10% of grade) · Due: end of Module 10.

This is the human-readable quiz with its vetted answer key and feedback. The import-ready Classic QTI is in F-quiz-week-10-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 10 misconceptions named in the lecture outline (confusing mitosis with meiosis, reversing the two divisions, the "23/46" gamete-count error, homologs vs. sister chromatids).

Questions, key, and feedback

Q1 (MC). A human body (somatic) cell is diploid with 46 chromosomes. How many chromosomes are in a human gamete (egg or sperm)?
- A. 92
- B. 23 ✅
- C. 46
- D. 12
Feedback: Gametes are haploid (n) — one complete set, 23 whole chromosomes. Meiosis halves 46 → 23 so that fertilization (23 + 23) restores the diploid 46. (92 would double it; 46 is the diploid body-cell number.)

Q2 (MC). During which event is the chromosome number actually reduced by half (from diploid to haploid)?
- A. meiosis I, when homologous chromosomes separate ✅
- B. meiosis II, when sister chromatids separate
- C. mitosis, when sister chromatids separate
- D. fertilization, when two gametes fuse
Feedback: Meiosis I is the reductional division — separating the homologous chromosomes takes the cell from 2n to n. Meiosis II separates sister chromatids (no further halving); fertilization restores the diploid number rather than reducing it.

Q3 (Multiple answer — select all that apply). Which of the following are true of meiosis?
- A. It produces four genetically unique haploid cells ✅
- B. It produces two genetically identical diploid cells
- C. It includes crossing over between homologous chromosomes in prophase I ✅
- D. It is preceded by one round of DNA replication ✅
- E. It is used for growth and tissue repair
Feedback: Meiosis makes four unique haploid cells (A), includes crossing over in prophase I (C), and is preceded by one round of DNA replication (D). Producing two identical diploid cells (B) and being used for growth/repair (E) describe mitosis, not meiosis.

Q4 (Matching). Match each cell-division fact to the correct description (each pairs with exactly one).
| Item | Correct description |
|---|---|
| Number of divisions in mitosis vs. meiosis | One in mitosis; two in meiosis |
| Daughter cells produced by mitosis | Two cells, genetically identical and diploid |
| Daughter cells produced by meiosis | Four cells, genetically unique and haploid |
| Event that occurs only in meiosis | Homologous chromosomes pair up and cross over |
Feedback: The classic contrast: mitosis = one division → two identical diploid cells; meiosis = two divisions → four unique haploid cells; and homolog pairing/crossing over happens only in meiosis (mitosis never pairs homologs).

Q5 (MC). What is the key event of meiosis I that makes it different from mitosis?
- A. sister chromatids separate
- B. homologous chromosomes pair up and then separate ✅
- C. the DNA is replicated a second time
- D. two haploid cells fuse into a diploid cell
Feedback: In meiosis I, homologous chromosomes pair (synapsis) and then separate — the event that halves the chromosome number. Sister chromatids separating (A) is meiosis II / mitosis; there is no second DNA replication (C); fusion of gametes (D) is fertilization.

Q6 (MC). Crossing over — the exchange of matching segments between homologous chromosomes — occurs during —
- A. prophase I of meiosis ✅
- B. metaphase II of meiosis
- C. prophase of mitosis
- D. interphase, before DNA replication
Feedback: Crossing over happens in prophase I, while the homologs are paired as a tetrad. It cannot occur in mitosis (homologs never pair there) or before replication (there are no sister chromatids yet to exchange).

Q7 (MC). An organism has 3 pairs of chromosomes (n = 3). From independent assortment alone, how many genetically different gametes can it produce? (Use 2ⁿ.)
- A. 3
- B. 6
- C. 8 ✅
- D. 9
Feedback: 2³ = 2 × 2 × 2 = 8. Each of the 3 pairs orients independently (two ways each), so the counts multiply. It is not 3 (the number of pairs) or 6 (the diploid number).

Q8 (MC). Humans have 23 pairs of chromosomes. From independent assortment alone, how many genetically different gametes can a person produce?
- A. 23
- B. 46
- C. 2²³ = 8,388,608 ✅
- D. 2 × 23 = 46
Feedback: 2²³ = 8,388,608 (over eight million) — each of the 23 pairs independently doubles the number of combinations, so you raise 2 to the 23rd power. (And crossing over makes the real total effectively unlimited.) "23," "46," and "2 × 23" all miss that each pair doubles the count.

Q9 (True / False). "Meiosis produces two genetically identical diploid cells."
- True
- False ✅
Feedback: False. That describes mitosis. Meiosis produces four cells that are haploid and genetically unique (thanks to crossing over and independent assortment).

Q10 (MC). Which statement correctly distinguishes homologous chromosomes from sister chromatids?
- A. They are the same thing — two names for one structure
- B. Homologous chromosomes are a matched pair (one from each parent); sister chromatids are two identical copies of a single chromosome joined at the centromere ✅
- C. Homologous chromosomes are made during DNA replication; sister chromatids come one from each parent
- D. Sister chromatids carry different genes; homologous chromosomes are identical copies
Feedback: Homologous chromosomes = the matched pair, one inherited from each parent (same genes, possibly different versions). Sister chromatids = the two identical copies of one chromosome produced by DNA replication, held together at the centromere. Option C reverses them; D swaps which one is "identical."

Answer key (quick reference)

Quality gate (self-checked): each single-answer item has exactly one correct option; the multiple-answer item lists the three true statements (A, C, D) and requires B and E to be left unselected; the matching item pairs four features to the two processes (each feature → exactly one process). Every numeric answer is pre-computed and independently re-verified by a Python check that re-derives 2ⁿ — n=2→4, n=3→8, n=4→16, n=23→8,388,608 — and printed PASS (quantitative gate: PASS); the load-bearing values here are Q7 (8) and Q8 (8,388,608), both engineered to clean, exact values. No item asserts a fact outside the Week 10 course definitions.

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

All ten items are tagged course=BIOL101 · week=10 · objective=5 · topic=meiosis-and-sexual-reproduction and deposited in Item Bank: Week 10 — Meiosis & Sexual Reproduction. The final (Week 16) and the per-term variant updates draw fresh items from this bank. (Tags: q1 ploidy-gamete-count, q2 reductional-division, q3 true-of-meiosis, q4 mitosis-vs-meiosis-match, q5 meiosis-I-key-event, q6 crossing-over-location, q7 2n-count-n3, q8 2n-count-human, q9 meiosis-not-identical, q10 homologs-vs-chromatids.)

Canvas placement block

canvas_object   = Quizzes::Quiz
title           = "Week 10 Quiz — Meiosis & Sexual Reproduction"
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"