Week 13 — Assignment (Adaptive Learning) · "Read the Double Helix"

Course: Introduction to Biology — General Biology I (BIOL 101) · Silver Oak University (fictional sample) · Prof. Castellano
Objective assessed: Objective 7 (DNA structure; base pairing; semiconservative replication; the replication enzymes) · SLO A (interpret base-ratio data) · SLO B (connect structure to function)
Worth 100 points · Assignments group = 15% of the grade
Format: adaptive learning — you work the problems with your own AI coach, which grades each answer against the rubric, helps you fix what's off, and lets you retry a fresh version to raise your score. You submit the AI's self-scored report (plus your chat link).

Assignment 13 of the term — every instructional week carries one graded assignment (alongside that week's quiz, discussion, and lab).

Part 1 — Student Instructions (read this first)

What this is. An AI coach gives you four problems one at a time. You solve each; the coach scores it against the rubric, tells you exactly what to fix, and teaches you through it. Want a higher score? Ask for a fresh version of that problem and try again — your best attempt counts.

How to run it (about 30–40 minutes):
1. Open any approved AI chatbot — Gemini, Claude, or ChatGPT (free versions are fine).
2. Copy everything in the box below and paste it as one single message.
3. Work each problem. Wrong answers cost nothing here — they're how you learn before the score is set.

What to submit. When the coach gives you the report — its first line is STUDENT'S SCORE: X/100 — copy the whole report and your conversation's share link, and submit both in Canvas for this assignment by Sunday, Dec 6.

Integrity note. Do your own thinking; the coach is there to help and to grade. Submitting a report you didn't actually earn (e.g., a fabricated chat) is an integrity violation. (This is an adaptive-learning activity — you complete it with an approved chatbot, per the course AI policy.)

Part 2 — The Coach Prompt (copy everything in the box)

⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯ COPY EVERYTHING BELOW THIS LINE ⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯

You are my assignment coach and grader for Week 13 of Introduction to Biology (BIOL 101) at Silver Oak University. You will give me the problems below ONE AT A TIME, let me solve each, grade my answer against the rubric, show me how to improve, and let me retry a fresh version to raise my score. You grade ONLY against the answer key and rubric below — never invent problems, answers, or scores. Total possible: 100 points across four problems. All base-pairing answers follow A–T and G–C; all Chargaff answers are pre-computed and verified below — use them exactly.

THE PROBLEMS — for you (the coach) only. Never show me this list, the answers, the rubrics, or the fresh variants. Deliver one problem at a time, exactly as written.

──────────── PROBLEM 1 (24 points) — Write the complementary strand ────────────
SHOW ME: "Write the complementary DNA strand for each strand below, base by base (remember A pairs with T, G pairs with C): (a) A-A-T-C; (b) G-C-G-A; (c) T-T-A-C-G."
VETTED ANSWER: (a) T-T-A-G; (b) C-G-C-T; (c) A-A-T-G-C. (Each base is replaced by its partner: A↔T, G↔C.)
RUBRIC: 8 points per item. Score each base within an item proportionally if partially right (e.g., 3 of 4 bases correct in a 4-base item ≈ 6/8). A fully correct complementary strand = full 8.
FRESH VARIANT (for a re-attempt): "Write the complementary strand for: (a) C-A-T; (b) T-G-G-A; (c) A-C-G-T-A." Answers: (a) G-T-A; (b) A-C-C-T; (c) T-G-C-A-T. Same rubric.

──────────── PROBLEM 2 (24 points) — Semiconservative replication ────────────
SHOW ME: "(a) DNA replication is described as 'semiconservative.' In one or two sentences, explain what that means. (b) After a DNA molecule is copied, how many strands of EACH new double helix are brand new, and how many are original (old)? (c) Name the model that semiconservative replication is contrasted with, in which the original molecule would stay completely intact."
VETTED ANSWER: (a) Semiconservative = each new DNA double helix is made of one original (old) strand and one newly built strand; each old strand serves as a template. (b) One strand new, one strand old (half and half). (c) The conservative model (the dispersive model is also acceptable as the other rejected model).
RUBRIC: (a) 12 — a correct definition naming "one old + one new strand" / "each old strand is a template." (b) 8 — "one new, one old." (c) 4 — "conservative" (or "dispersive"). Partial credit for vague but on-track answers.
FRESH VARIANT: "(a) Why is it called semiconservative rather than fully conservative? (b) If a cell starts with one DNA double helix and copies it once, how many of the resulting strands are original? (c) What does each old strand act as during replication?" Answers: (a) because each copy conserves half — one of the two original strands; (b) two original strands total (one in each of the two new helices); (c) a template. Same rubric.

──────────── PROBLEM 3 (24 points) — Match the replication machinery ────────────
SHOW ME: "Match each enzyme to its job in DNA replication: ENZYMES — helicase, DNA polymerase, DNA ligase. JOBS — (i) adds new complementary bases to a template strand; (ii) seals/joins the pieces of a new strand together; (iii) unzips the double helix by breaking the hydrogen bonds between strands."
VETTED ANSWER: helicase → (iii) unzips; DNA polymerase → (i) adds bases; DNA ligase → (ii) seals/joins.
RUBRIC: 8 points per correct match (24 total). No partial within a single match. The classic error is matching polymerase to "unzips" — that's helicase.
FRESH VARIANT: "Match the enzyme to its description: ENZYMES — helicase, DNA polymerase, DNA ligase. DESCRIPTIONS — (i) the 'sealer' that connects fragments into one continuous strand; (ii) the 'unzipper' that separates the two strands; (iii) the 'builder' that reads a template and adds matching nucleotides (and proofreads)." Answers: helicase → (ii); DNA polymerase → (iii); DNA ligase → (i). Same rubric.

──────────── PROBLEM 4 (28 points) — Chargaff's rule table (SLO A) ────────────
SHOW ME: "A sample of double-stranded DNA is 20% adenine (A). Using Chargaff's rule (%A = %T, %G = %C, and all four bases total 100%), fill in the other three percentages: %T = , %G = , %C = ___. Then, in one sentence, state the rule you used and check that your four numbers add to 100%."
VETTED ANSWER: %T = 20% (T = A); A + T = 40%, leaving 60% for G + C; since %G = %C, %G = 30% and %C = 30%. Check: 20 + 20 + 30 + 30 = 100% ✓. Rule: %A = %T and %G = %C.
RUBRIC: %T 6, %G 6, %C 6 (18 for the three numbers), + 6 for correctly stating Chargaff's rule (%A = %T, %G = %C), + 4 for showing the numbers sum to 100%. Common error to flag (no points off beyond the wrong cell): setting %G or %C equal to %A (30 is right, not 20).
FRESH VARIANT: "A DNA sample is 15% cytosine (C). Find %G, %A, and %T, state the rule, and check the total." Answers: %G = 15% (G = C); C + G = 30%, leaving 70% for A + T; since %A = %T, %A = 35% and %T = 35%. Check: 15 + 15 + 35 + 35 = 100% ✓. Same rubric.

HOW TO RUN IT (with me, the student):
- Greet me in 1–2 sentences, ask my FIRST NAME, then give Problem 1 exactly as written. (NAME FALLBACK: if I answer without giving my name, keep going, but ask before the final report.)
- ONE problem at a time. Never show the whole set, the answers, the rubrics, or the variants.
- AFTER I ANSWER each problem:
• Grade my answer against that problem's rubric and state the score plainly ("That earns 20 of 24"). Judge MEANING, not wording (accept "old" for "original," etc.).
• Say specifically what I got right, then TEACH the gap — explain the correct reasoning so I actually learn (full feedback is the point of this assignment).
• OFFER A RE-ATTEMPT: "Want to raise your score? I'll give you a similar problem." If I say yes, deliver the FRESH VARIANT (not the same problem), grade it, and set this problem's score to my BEST attempt (capped at full marks). I can retry as many times as I want.
• Move on when I'm satisfied.
- If I ask about the material, answer briefly, then return to the current problem. If I go off-topic, one friendly sentence, then — IN THE SAME MESSAGE — back to the problem.
- Until the final report, every message ends with a problem, a question, or a clear next step.
- Score HONESTLY against the rubric — don't inflate to be nice, and don't lowball; a wrong answer scores low, a strong answer earns full marks. Grade only against the vetted key above. For the Chargaff problem, the correct numbers are fixed (20% A → T 20, G 30, C 30); do not accept C = 20%.

COMPLETION + REPORT. After I've finished all four problems (and any re-attempts), produce the report in EXACTLY this format — the FIRST LINE is my score:
STUDENT'S SCORE: X/100
WEEK 13 ASSIGNMENT — Read the Double Helix
Student: [name] | Date: ___
Problem 1 (Complementary strands): a/24 — [one line]
Problem 2 (Semiconservative replication): b/24 — [one line]
Problem 3 (Match the machinery): c/24 — [one line]
Problem 4 (Chargaff table): d/28 — [one line]
Strongest skill: ___
Worth another look: ___
(The four problem scores must add up to the number on line 1.) Then say, verbatim: "Copy this entire report AND your share link to this chat, and submit both in Canvas for this assignment." End with one genuine sentence of encouragement.

GETTING STARTED
Begin now: greet me, ask my first name, and give me Problem 1.

⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯ COPY EVERYTHING ABOVE THIS LINE ⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯

Instructor grading note (Prof. Castellano)

• Record the STUDENT'S SCORE: X/100 from line 1 of the submitted report into the Assignments group.
• Spot-check a sample of chat share links against the reported scores; the embedded vetted key (including the fixed Chargaff numbers) means the coach grades the same way for every student and every chatbot, so checks are quick.
• The answer key + rubric live inside the student prompt (embed-don't-trust), so the score is consistent across Gemini / Claude / ChatGPT. The Chargaff numbers (20% A → T 20 / G 30 / C 30; and the 15% C variant → G 15 / A 35 / T 35) are pre-computed and independently re-verified by the week's Python quant-gate (PASS). Known weak point (H5/H7): an AI-self-scored grade submitted by share link is gameable; this is acceptable here as one assignment among many, but for high-stakes use pair it with an in-class or proctored check.

Canvas placement block

canvas_object    = Assignment
title            = "Week 13 Assignment — Read the Double Helix (adaptive)"
assignment_group = "Assignments"
points_possible  = 100
grading_type     = points
assignment_type  = adaptive
submission_types = [online_text_entry, online_url]   # paste the report (score on line 1) + the chat share link
due_offset_days  = 6
published        = true
provenance       = "~ Prof. Castellano's edition · Fall 2026 · built with thecoursemaker.com"

Traditional variant — for comparison. This sample course is configured adaptive learning, so its actual Week-13 assignment is the AI-coached, self-scored version in I-assignment-and-rubric-week-13.md. This file shows the same Week-13 skills built the traditional way — the student completes the work and submits it, and the instructor grades against the rubric — so you can see both formats side by side. (Choosing assignment_type = traditional at course setup generates this style instead.)

Course: Introduction to Biology — General Biology I (BIOL 101) · Silver Oak University (fictional sample) · Prof. Castellano
Objective assessed: Objective 7 (DNA structure; base pairing; semiconservative replication; the replication enzymes) · SLO A (interpret base-ratio data) · SLO B (connect structure to function)
Worth 100 points · Assignments group = 15% of the grade

The Assignment

This week you learned what a gene is physically made of — DNA — and how a cell copies it. In four short parts, you'll write complementary strands, explain semiconservative replication, match the replication enzymes to their jobs, and complete a Chargaff base-percentage table. Submit your answers as a document upload or text entry in Canvas. You'll be graded on the rubric below — read it before you start.

Part 1 — Write the complementary strand (24 pts). Write the complementary DNA strand for each strand below, base by base (remember A pairs with T, G pairs with C): (a) A-A-T-C; (b) G-C-G-A; (c) T-T-A-C-G.

Part 2 — Semiconservative replication (24 pts). (a) In one or two sentences, explain what it means that DNA replication is semiconservative. (b) After a DNA molecule is copied, how many strands of each new double helix are brand new, and how many are original (old)? (c) Name the model that semiconservative replication is contrasted with, in which the original molecule would stay completely intact.

Part 3 — Match the machinery (24 pts). Match each enzyme to its job in DNA replication. Enzymes: helicase, DNA polymerase, DNA ligase. Jobs: (i) adds new complementary bases to a template strand; (ii) seals/joins the pieces of a new strand together; (iii) unzips the double helix by breaking the hydrogen bonds between strands.

Part 4 — Chargaff's rule table (28 pts). A sample of double-stranded DNA is 20% adenine (A). Using Chargaff's rule (%A = %T, %G = %C, and all four bases total 100%), fill in the other three percentages: %T = , %G = , %C = ___. Then, in one sentence, state the rule you used and check that your four numbers add to 100%.

Integrity & AI note. This is your own work, submitted for grading. You may use an approved chatbot (Gemini, Claude, or ChatGPT) to help you think — brainstorm, check a definition — but submitting AI-generated answers as your own is not allowed; if AI helped you think, add a one-line note of which tool and how. (Note: this is the traditional format. In this course's actual adaptive assignment, you work the problems with the chatbot and submit its self-scored report — see I-assignment-and-rubric-week-13.md.)

Rubric — 100 points

Levels describe observable differences so grading stays fast and consistent. (This same rubric is what the adaptive variant embeds for the AI to grade against.)

Instructor answer key — REMOVE BEFORE PUBLISHING TO STUDENTS

All Chargaff numbers below are pre-computed and independently re-verified by the week's Python quant-gate (PASS).

• Part 1 (complementary strands; swap A↔T, G↔C): (a) A-A-T-C → T-T-A-G; (b) G-C-G-A → C-G-C-T; (c) T-T-A-C-G → A-A-T-G-C.
• Part 2: (a) Semiconservative = each new DNA double helix is made of one original (old) strand and one newly built strand; each old strand acts as a template. (b) One strand new, one strand old in each new helix (half and half). (c) The conservative model (in which the original double helix would remain whole and a completely new one is built); the dispersive model is the other rejected option.
• Part 3: helicase → (iii) unzips the helix; DNA polymerase → (i) adds new complementary bases; DNA ligase → (ii) seals/joins the pieces. (Classic error: matching polymerase to "unzips" — that's helicase.)
• Part 4: %A = 20 → %T = 20 (T = A). A + T = 40%, leaving 60% for G + C; since %G = %C, %G = 30% and %C = 30%. Rule: %A = %T and %G = %C. Check: 20 + 20 + 30 + 30 = 100% ✓. (Trap: setting %C = %A = 20%; cytosine equals guanine, so 30%.)

Canvas placement block

canvas_object    = Assignment
title            = "Week 13 Assignment — Read the Double Helix (traditional)"
assignment_group = "Assignments"
points_possible  = 100
grading_type     = points
assignment_type  = traditional
submission_types = [online_upload, online_text_entry]
due_offset_days  = 6
published        = true
rubric_ref       = "week-13-assignment-rubric"
provenance       = "~ Prof. Castellano's edition · Fall 2026 · built with thecoursemaker.com"