Clue 1: Orient yourself
Which factors differ between gardens?
Use the labels and the picture's left-to-right, near-to-far, or before-and-after order. Name only what you can point to.
The question
Which factors differ between gardens?
Why it matters: Genetic results can change family counseling and research decisions. They must be interpreted without turning risk into destiny or an uncertain variant into a diagnosis. Today you practice the professional reasoning behind that work: Population differences reflect allele frequencies, effect sizes, environments, and sampling, not biological ranking of groups.
On your WebXam
Reasoning about ancestry-dependent genetic architecture and replication
For life
One result can have many causes; the outcome alone never tells you which.
Principle: Many roads, one ending
Five principles we return to
Having it is not using it
Same instructions, different switches
Same look, different cause
Change one thing and watch
Boss or doorman?
Decides the result or only allows it
Held down, not gone
Remove the brake and it returns
Many roads, one ending
One result can begin many ways
Try the everyday version first
Different gardens contain different seed mixes and weather
Gardens can differ in seeds, soil, water, sunlight, and care. Similar plants may grow differently because several starting conditions act together.
Do not jump to the biology yet. Treat the picture as a small system. Track its parts, follow one change at a time, and keep more than one explanation open until the picture supplies a way to separate them.
Clue 2: Trace one change
Why can the same seed behave differently?
Follow one object, stage, or path. Point to the first place where the situation changes instead of jumping to the ending.
Clue 3: Keep the cause open
What would replication across gardens test?
List more than one explanation that still fits. Name the extra observation that would help you separate those possibilities.
Now inspect the illustration
Work from the visible evidence. A useful answer names the part of the picture that supports it and leaves unknown causes open.
- 1Which factors differ between gardens?
- 2Why can the same seed behave differently?
- 3What would replication across gardens test?
Tier 1 check
Finish with the everyday model
Use the everyday picture to answer today's question in plain words: Which factors differ between gardens?
You can complete today's required check without opening the technical details below.
Ready for the real names? Optional tier 2
Technical rules and limits
Rule 1: Separate ancestry from race labels.
Rule 2: Compare how common a change is and how strongly it shifts risk.
Rule 3: Require repeated results and consider environment and sampling.
Where the analogy stops: Human populations are not isolated gardens, and ancestry is continuous and shared.
Carry the previous idea forward
Knockout and rescue experiments strengthen causation when loss creates a defect and restoration reverses part of it.
Today's technical takeaway
Population differences reflect allele frequencies, effect sizes, environments, and sampling, not biological ranking of groups.
Now map the same rules onto biology
Interpret cleft prevalence and IRF6 risk across populations
Seed mix
Allele frequencies
Weather
Environmental and social context
Flower count
Population prevalence
Educational illustration, not a clinical photograph or diagnostic result. Use the labeled evidence cards and claim ceiling.
Mateo's case file: evidence supplied in this lesson
GEN16-E1
Cleft prevalence differs among studied populations.
Why it matters: Population pattern is real but descriptive.
GEN16-E2
Risk-allele frequencies and effect estimates can differ by ancestry and study.
Why it matters: Genetic contribution is population-context dependent.
GEN16-E3
Within-group variation is large and ancestry groups overlap.
Why it matters: Population averages do not determine an individual outcome.
Make the clinical decision
You are reviewing a public-health infographic.
The draft says one ancestry group is genetically destined to have more clefts.
AReplace it with frequency, context, overlap, and replication language.
BKeep the destiny claim.
CErase population data entirely.
Choose the correction and cite both difference and overlap evidence.
Evidence required
GEN16-E1 + GEN16-E2 Claim ceiling
You may discuss population statistics. You may not rank groups biologically or predict an individual from ancestry alone.Go deeper Optional tier 3
Everything required for today is above. Open these only if you want the explainer, source trail, or download files.
The everyday model and Tier 1 check are the complete required path for this lesson.
Use these checks to keep your place. They are not turned in through the portal.
Check off as you finish
- Worked through the everyday picture and answered its three questions.
- Completed the Tier 1 check in plain words.
Turn in: Genetics lesson 16: Why Is CL/P More Common in Some Groups?
Go to Schoology to turn this in.
Submit one PDF. Put your first and last name in the document header. Name the file: FirstName LastName - Assignment Title - YYYY-MM-DD.pdf.
Open Schoology PDF upload helpIf you cannot get in, see Mr. Mendoza. Do not skip the work.
Optional legacy technical materials Open only if you want the original notes, vocabulary, artifact, and CER work
Before this page, you should know
- A is an animal studied to learn about a human process; mice and zebrafish are the workhorses for clefting.
- A is an animal with a chosen gene deliberately switched off, compared against a normal wild-type animal.
If not, review
Today's new idea is only
risk is built from many small-effect alleles plus environment crossing a threshold, and because frequencies and effects differ by ancestry, a risk variant found in one group may not transfer to another.
Goal: Explain how , ancestry, , and a combine to make CL/P more common in some populations, and why a risk score built in one group transfers poorly to another.
Know by the end
- is how common a particular version of a gene is in a population; it differs by ancestry.
- An reports how many times more likely an outcome is per copy of a (1.0 means no effect).
- The polygenic model says many small risk factors add up, and the trait appears only once total liability crosses a cutoff.
- Replication means a real association should reappear in independent samples; the 8q24 (rs987525) signal is strong in Europeans but absent in Native-American-ancestry families, and rs642961 near IRF6 fails to replicate in African-ancestry samples.
- gnomAD reports broken down by ancestry, so you can read for yourself how the same variant is common in one group and rare in another.
1
How cleft risk is built
Model start: risk is not one gene flipping on or off. It is built from many small pieces that add up.
- The fraction of people in a group who carry a given risk variant is its ____.
- Because frequencies differ by ____, the same variant can be common in one group and rare in another.
- The polygenic ____ ____ model says many small-effect alleles plus environment add up, and a appears only when total liability crosses a cutoff.
2
Why risk does not transfer between groups
- A real association should reappear in independent samples; this idea is called ____.
- When the 8q24 signal (strong in Europeans) does not replicate in Asian or Native-American-ancestry samples, that is evidence of ancestry-dependent genetic ____.
- matters too: mothers who smoke and whose fetus lacks active detoxifying enzymes have roughly ____-fold higher risk.
Everything you need for today is on this page. These links are optional.
What to read
Read the short plain-language explanation written for this lesson. Plain-language explainer for this lesson
Why this source matters
This explanation gives you the background for today's idea without making you decode a research paper: risk is built from many small-effect alleles plus environment crossing a threshold, and because frequencies and effects differ by ancestry, a risk variant found in one group may not transfer to another.
Words to unlock first
Reading moves
- Skim the title and abstract first to get the gist.
- Circle the one sentence that states the main claim.
- Box the evidence the authors give for that claim.
- Mark one sentence that confuses you, and move on.
Stop point
Stop after the final 'Use it now' section. The research citations are available separately for advanced readers.
Your output
Write one claim-evidence sentence: state the main idea, then name the example or evidence that supports it.
Where this fits
Tested on (Ohio WebXam)
Genetics of Disease · 072130
PLTW lesson
MI · Genetics domain · Genetics and population health; risk factors
WebXam domain
Molecular and Genetic Technology
Evidence to produce
A research consortium hands you a draft polygenic risk score for CL/P built entirely from European data and asks you to sign off for global clinical use. In three to four sentences, give your recommendation and cite at least two pieces of evidence (for example the 8q24 non-replication in Guatemalan families and the rs642961 non-replication in African-ancestry samples), then say what data you would need before the score could be trusted in a new population.
Lab / skill
Medical Interventions (MI) · AP Biology
Everything required for today's decision is already in the case file and plain-language explainer. The links below are original papers and database records for teachers and advanced readers, not assigned student reading.
- Rahimov et al. 2008, AP-2alpha site in an IRF6 enhancer and cleft lip (Nat Genet)
- Beaty et al. 2010, GWAS of CL/P, MAFB and ABCA4 (Nat Genet)
- Birnbaum et al. 2009, 8q24 susceptibility locus for nonsyndromic cleft lip (Nat Genet)
- Bezerra et al. 2019, IRF6 polymorphisms in Brazilian nonsyndromic CL/P (Braz J Otorhinolaryngol)
- gnomAD (Broad Institute): allele frequency by ancestry, search variant rs642961
- Claim: A polygenic risk score for CL/P built in one population may not work in another.
- Evidence: rs987525 has an near ____ in Europeans but shows no evidence in Guatemalan families, and rs642961 fails to replicate in ____-ancestry samples.
- Reasoning: Because and effect differ by ancestry, a score built in one group is ____ in another.
How this is graded (rubric)
For: A research consortium hands you a draft polygenic risk score for CL/P built entirely from European data and asks you to sign off for global clinical use. In three to four sentences, give your recommendation and cite at least two pieces of evidence (for example the 8q24 non-replication in Guatemalan families and the rs642961 non-replication in African-ancestry samples), then say what data you would need before the score could be trusted in a new population.
| Criterion | Proficient | Developing | Beginning |
|---|---|---|---|
| Complete | Every required part of the artifact is present and filled in. | Most parts are present, but one is missing or left blank. | Several parts are missing. |
| Accurate | The science and data are correct and match the evidence. | Mostly correct, with a small factual slip. | Key science or data is wrong. |
| Scientific reasoning (CER) | States a claim, backs it with specific evidence, and explains the reasoning. | Has a claim and evidence, but the reasoning is thin or missing. | Gives an answer with no evidence or reasoning. |
| Professional communication | Clear, organized, and labeled the way a clinician or scientist would write it. | Readable but disorganized or missing labels. | Hard to follow. |
| Submitted | Turned in through the route named under Submit here and confirmed. | Turned in, but in the wrong place or unconfirmed. | Not turned in. |
How the model answer scores against this rubric
- CompleteProficient: Nothing is left blank: the model fills every part of "A research consortium hands you a draft polygenic risk score for CL/P built entirely from European data and asks you to sign off for global clinical use. In three to four sentences, give your recommendation and cite at least two pieces of evidence (for example the 8q24 non-replication in Guatemalan families and the rs642961 non-replication in African-ancestry samples), then say what data you would need before the score could be trusted in a new population.".
- AccurateProficient: Every number and claim matches the case evidence.
- Scientific reasoning (CER)Proficient: It names a claim, cites the specific evidence, and explains the reasoning, not just the answer.
- Professional communicationProficient: It is organized and labeled like a real chart note.
- SubmittedProficient: It would be attached to your class form or handed in, and confirmed.
What's next: We found why CL/P differs across whole populations, but population averages are not a family. Mateo's parents now ask the practical question: if they have another child, what is the chance that child also has a ? That family is what we chase next.