Week 12 · Biology Lab & Inquiry

Week 12 Biology Lab & Inquiry: Blood-Type & Pedigree Detective

Introduction to Biology Free sample edition

Part 1 — The Big Picture

This week you learned that Mendel's cross mechanics still work when his simple rule bends: a heterozygote can be a blend (incomplete dominance) or show both versions at once (codominance), the ABO gene has three alleles in the population, and an X-linked recessive allele shows in a male with one copy because a son's only X comes from his mother. You also learned to read a family chart, a pedigree, with two decisions in order. In this lab you are the detective. You work a case file of three made-up family crosses, drawing every Punnett square and counting the boxes, and you read two made-up family charts described in words. You can check your blood-type and sex-linkage reasoning against the Learn.Genetics pages. Then you check a chatbot's account of your case file and catch where it garbles a ratio, oversimplifies codominance, mislabels where an allele rides, swaps mitosis for meiosis, makes the chart decisions out of order, or invents a number.

Time budget: Plan for about 120 minutes.

Part 2 — The Task

Guiding question: Given each family's parents, what are the odds for their children, and which pattern of inheritance does each family chart point to when you make the two decisions in order?

Before you begin — hypothesis: Before you work the case file, write one hypothesis in the if… then… because… form about Chart A: if the trait in Chart A is X-linked recessive, then the affected people should be mostly sons of unaffected parents, because of a reason about where a son's X comes from that you can state. Then predict whether Chart B can be X-linked recessive.

Workshop data: The detective's case file: three family crosses and two family charts described in words

Source: A case file constructed for this lab: three made-up family crosses and two made-up family charts, printed in full in the tables in Part 4, with the Learn.Genetics Genes and Blood Type and Sex Linkage pages as an optional virtual check.

Rows: 3 family crosses and 2 family charts of 5 people each; the case table has 3 rows, the chart table has 10 rows (one per person) with a column for a genotype that fits, and the decision table has 4 rows
Columns: case, parents' genotypes, pattern, the four boxes, and the probability asked for; and for the charts, person, generation, symbol, and whether the person shows the trait
Unit: genotypes, blood types, and probabilities written as reduced fractions

Part 3 — Materials & Procedure

Tools and materials

Free virtual labs and simulations (PhET, HHMI BioInteractive, Learn.Genetics), a virtual microscope, and a spreadsheet (Google Sheets or any free spreadsheet)
A web browser and an internet connection, for the optional Learn.Genetics Genes and Blood Type and Sex Linkage pages
Pencil and paper for drawing Punnett squares, and a document or notebook for your written answers

Ways of working

virtual-simulation-inquiry
at-home-protocol-and-data-table
figure-and-diagram-interpretation

Procedure

Before you work any case, fill in the first table in Part 4: your hypothesis about Chart A, your prediction about Chart B, and the two decisions you will use to read a family chart, in order. Tool: Free virtual labs and simulations (PhET, HHMI BioInteractive, Learn.Genetics), a virtual microscope, and a spreadsheet (Google Sheets or any free spreadsheet). Check: The first table has an if… then… because… hypothesis, a prediction for Chart B, and the two decisions written in order.
For Cases 1, 2, and 3 in the case table, draw a Punnett square on paper: one parent's two gametes across the top and the other parent's two down the side. Fill all four boxes, then write the four boxes in words in the table. Tool: Free virtual labs and simulations (PhET, HHMI BioInteractive, Learn.Genetics), a virtual microscope, and a spreadsheet (Google Sheets or any free spreadsheet). Check: Four boxes written in words for each of the three cases.
Count the boxes to find each probability the case asks for, and write each as a reduced fraction. If you use a spreadsheet, type a count of boxes over 4, such as =2/4, and check the decimal it returns against your fraction. Tool: Free virtual labs and simulations (PhET, HHMI BioInteractive, Learn.Genetics), a virtual microscope, and a spreadsheet (Google Sheets or any free spreadsheet). Check: Six probabilities in all across the three cases, each a reduced fraction with its box count shown.
Optional virtual check: in a web browser, open the Learn.Genetics Genes and Blood Type page and match each blood type to the alleles that make it, then open the Learn.Genetics Sex Linkage page and find why an X-linked recessive trait shows up more often in males. Note one sentence from your own reading of each page that supports your case answers. Tool: Free virtual labs and simulations (PhET, HHMI BioInteractive, Learn.Genetics), a virtual microscope, and a spreadsheet (Google Sheets or any free spreadsheet). Check: Two short notes in your own words, one on blood-type alleles and one on sex linkage.
Read Chart A and Chart B in the chart table person by person. For each chart, make decision one (dominant or recessive) and then decision two (autosomal or X-linked), and fill in the decision table, naming any obligate carrier by generation and number. Tool: Free virtual labs and simulations (PhET, HHMI BioInteractive, Learn.Genetics), a virtual microscope, and a spreadsheet (Google Sheets or any free spreadsheet). Check: Both decisions made in order for each chart, with the reason written beside each one.
For Chart A, use the carrier cross to give the probability that a future son of the couple in generation I shows the trait, and write what a family this small cannot rule out. Tool: Free virtual labs and simulations (PhET, HHMI BioInteractive, Learn.Genetics), a virtual microscope, and a spreadsheet (Google Sheets or any free spreadsheet). Check: A probability for a future son written as a reduced fraction, and one sentence naming what the chart cannot rule out.

Fallback route

When to use it: Use this route if the Learn.Genetics pages will not load, or if you cannot get online.

Skip the optional virtual check in step 4 and complete every table, analysis question, and the critique step from the case file printed in Part 4, which holds everything the lab needs. Submit the same items for equal credit; in place of the two notes from the Learn.Genetics pages, write one sentence for each from this week's chapter.

This route earns the same credit as the primary route.

Part 4 — The Scaffold

Name your hypothesis and your method before you open the case file, so your reading is fair from the start.

Student scaffold table 1
Part of the investigation	Your answer
Hypothesis about Chart A (if… then… because…)
Prediction: can Chart B be X-linked recessive?
Decision one for reading a family chart
Decision two for reading a family chart

Work each family cross box by box, then count the boxes to find the probabilities the case asks for.

Student scaffold table 2
Case	Parents and pattern	Probability asked for
Case 1: a garden	A pink snapdragon (RW) crossed with a white snapdragon (WW); incomplete dominance	P(pink) =
Case 2: a family's blood types	A type AB parent (IᴬIᴮ) and a type A parent who carries i (Iᴬi); multiple alleles with codominance	P(type AB) = ; P(type O) =
Case 3: a family with an X-linked recessive trait	A carrier mother (XᴬXᵃ) and an affected father (XᵃY)	P(a son is affected) = ; P(a daughter is affected) =

Read each family chart person by person; each row describes one symbol in words.

Student scaffold table 3
Chart	Person	Generation	Symbol	Shows the trait?
A	I‑1	I	square (male)	no
A	I‑2	I	circle (female)	no
A	II‑1	II	square (male)	yes
A	II‑2	II	circle (female)	no
A	II‑3	II	square (male)	yes
B	I‑1	I	square (male)	no
B	I‑2	I	circle (female)	no
B	II‑1	II	circle (female)	yes
B	II‑2	II	square (male)	no
B	II‑3	II	circle (female)	no

Make the two decisions in order for each chart and give the reason for each.

Student scaffold table 4
Chart and decision	Your decision	Your reason
Chart A, decision one: dominant or recessive?
Chart A, decision two: autosomal or X-linked?
Chart B, decision one: dominant or recessive?
Chart B, decision two: autosomal or X-linked?

Part 5 — Analysis Questions

Show the box counts behind all six probabilities: P(pink) in Case 1, P(type AB) and P(type O) in Case 2, P(a son is affected) and P(a daughter is affected) in Case 3, and P(a future son is affected) in Chart A. Write each as a reduced fraction.
Case 1 and Case 2 both have heterozygotes you can see. Explain which case shows a blend and which shows both versions at once, name each pattern, and say why Case 2 can never give a type O child.
Case 3 has an affected father. Explain why this cross, unlike a cross with an unaffected father, can give an affected daughter, using where each daughter's two X chromosomes come from and which division of meiosis puts one of the mother's two X chromosomes into each egg.
Compare Chart A and Chart B. Both show an affected child of unaffected parents. Explain why Chart A is consistent with X-linked recessive while Chart B cannot be, naming the obligate carrier in Chart A. Does your evidence support or fail to support your hypothesis?
Choose one and answer it in 3–4 sentences. (a) Chart A has only five people: name one other pattern a chart this small cannot rule out, and say what new family member would help settle it. (b) The case file is made up: name one way real families differ from a four-box Punnett square, and say how that limits what a probability can promise one couple.

Part 6 — AI-Critique Moment

Choose one equal-credit critique route. Route A: ask an approved AI tool to critique your completed work, then check its response against your own evidence. Route B is the no-AI equivalent printed below.

Approved tools: Claude, Gemini, ChatGPT, Grok, Microsoft Copilot.

Prompt to paste:

I've pasted my completed Week 12 Biology Lab & Inquiry tables above. They cover three family cases and two family charts described in words. Please do six things. First, check my four boxes and my probability for a pink snapdragon (RW) crossed with a white one (WW), and give the color ratio. Second, say whether a type AB blood cell shows a blend of A and B or both at once, and name the pattern. Third, for a carrier mother and an affected father with an X-linked recessive trait, say which parent gave each son his X and which chromosome carries the allele. Fourth, say which division of meiosis puts only one of a mother's two X chromosomes into each egg. Fifth, list the two decisions for reading a family chart in the order they should be made, and apply them to my Chart A. Sixth, tell me the exact percentage of people worldwide who have type O blood, with its source.

Test the response for these likely failures:

Chatbots often give a pink-by-white snapdragon cross as 3 pink : 1 white or as 1 red : 2 pink : 1 white, borrowing a ratio from a different cross.
Chatbots sometimes call the AB blood type a blend or a mix of A and B, the way a pink flower is a blend.
Chatbots sometimes say a son received his X-linked allele from his father, or place the recessive allele on the Y chromosome.
Chatbots sometimes say mitosis splits a mother's two X chromosomes into separate eggs, or that an egg keeps both X chromosomes.
Chatbots often jump straight to X-linked because the affected people are male, before deciding whether the trait is dominant or recessive.
Asked for a worldwide type O percentage, chatbots often state a precise figure and cite a source that was never given.

Write 3–5 sentences naming one thing the chatbot got right and at least two places it went wrong or overreached, quoting its words and correcting each with evidence from your own tables or this week's chapter.

Equivalent route (no AI required)

No AI account is required for this lab. Instead of the chatbot, critique this flawed analysis, printed here in full: "A pink snapdragon crossed with a white one gives 3 pink to 1 white, the usual ratio. A type AB person has blood that is a blend of A and B, halfway between the two. In Case 3, every affected son got the allele from his father, because the allele rides on the Y chromosome. Each egg gets one of the mother's X chromosomes because the X chromosomes split apart in mitosis. For Chart A, the affected people are all males, so the trait is X-linked, and only after that can you ask whether it is recessive. About 45 percent of people worldwide have type O blood, according to a large survey." Mark it up: quote each flawed sentence, name what is wrong (a garbled ratio, an over-simplified mechanism, a mislabeled structure, a mitosis-for-meiosis swap, a mis-ordered process, or an invented figure), cite the evidence from your tables or this week's chapter, and write a corrected sentence beneath it. This route assesses the same objectives (Objective 5 and Objective 6) as the chatbot critique, takes comparable effort (about 30 minutes and 200–300 words), is scored by the same scoring criteria for the same credit, and its own submission artifact is the marked-up flawed analysis, posted in place of the chatbot share link and report.

Part 7 — What to Submit

All four completed scaffold tables, including the four boxes and the probabilities for each case
Written answers to all five analysis questions
The chatbot critique report with its share link, or the equivalent route's marked-up flawed analysis

Deliverable:

A short Biology Lab & Inquiry report on the blood-type and pedigree case file: four completed tables (your hypothesis and the two decisions, the three family crosses with their boxes and probabilities, the two family charts read person by person, and the decisions for each chart), written answers to five analysis questions, and a critique of a chatbot's account of your case file, or, on the equivalent route, a marked-up correction of the printed flawed analysis. Submit in any accessible file type or as a link; a recorded response may be submitted as audio or video with a transcript, or as text. Choose a written, recorded, or visual form for your answers; every form is graded by the same scoring criteria.

Rubric

The rubric below shows how each submitted part is evaluated; bands are full, partial, or none.

Workshop evaluation criteria
Criterion	Full	Partial	None
Testable hypothesis and the method of reading a chart	A falsifiable if… then… because… hypothesis about Chart A and a prediction about Chart B appear before the case file is worked, and the two decisions are written in the right order.	A hypothesis appears but is not falsifiable or lacks the prediction, or the two decisions are missing or out of order.	No hypothesis, or the method of reading a chart is not named.
Family crosses with boxes and probabilities	All three crosses have four correct boxes written in words, and all six probabilities are correct reduced fractions with their box counts shown.	The crosses are worked, but one or two boxes or probabilities are wrong, or the box counts are not shown.	No crosses are worked, or the probabilities are given without any boxes.
Pattern analysis: blend, both at once, sex linkage, and the two charts	Questions 1 to 4 are answered accurately: the blend is kept apart from both at once, the affected daughter in Case 3 is explained through her two X chromosomes and meiosis I, Chart A is read as consistent with X-linked recessive with the obligate carrier named, and Chart B is shown not to be X-linked recessive.	Some of questions 1 to 4 are accurate, but a blend and both at once are blurred, an allele is placed on the wrong chromosome, or a chart is read by shading alone.	Questions 1 to 4 are missing or inaccurate throughout.
Critique of the chatbot or of the printed flawed analysis	On either route, at least two errors are quoted and corrected with evidence from the student's own tables or the chapter, and one correct point is acknowledged; both routes earn this band equally.	On either route, errors are named but corrected without evidence, or only one error is caught.	No critique appears, or pasted output is submitted without any checking.
Reflection on the limits of the case file	The chosen reflection option is answered in 3–4 sentences that tie a specific limit of a small chart, or a specific difference between real families and a four-box square, to a concrete change in what can be claimed.	The reflection is answered but stays general or names no specific change.	No reflection is submitted.

Quality Gate

Every probability comes from four boxes you drew and counted, never from memory or a chatbot.
Each probability is a reduced fraction with its box count shown.
The hypothesis was written before you worked the case file and has the if… then… because… form.
Each chart is read with decision one before decision two, and the reason for each decision is written.
A blend is kept apart from both at once, and every X-linked allele is placed on the X chromosome.
No measurement, percentage, study, or source is invented anywhere in the submission.
The critique quotes the chatbot or the flawed analysis and corrects at least two errors with evidence from your tables or the chapter.

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