Two Shelves Become One Roof: Adhesion, the Medial Edge Epithelium, and the Seam
Developmental domain · Lesson 8 of 20 · Principles of Biomedical Science (PBS)
Today's goal: Describe how the two elevated shelves adhere at their medial edge epithelium and form a single midline epithelial seam, and explain why a non-stick surface layer must be removed first.
What a finished product looks like
This is a model of the work you should turn in. Use it to check your own: match the structure and the level of detail, do not copy it. Your wording should be your own.
From outside in at the moment of touching:
1. Periderm (rounding up and being shed)
2. Medial edge epithelium (MEE)
3. Midline epithelial seam (MES) forming where the two MEE layers meet
4. Mesenchyme (the inner core)
Why periderm goes first: the periderm is a non-stick wrapper, so at the one spot where the shelves must stick, it has to be cleared on schedule or the bare MEE layers can never adhere into a seam. Chart note: Act 3 begins, shelves adhere into a seam.
How this was built, step by step
The finished product above did not appear all at once. Here is the path from the question to the turned-in work, so you can follow the same steps.
- 1Start from today's question: How do the touching edges of two separate shelves become a single, joined roof?
- 2Work the Model and the Explore questions to reason it out before writing anything.
- 3Pull the specific evidence the product needs from the reading and any database you used.
- 4Write it up in the required format: Annotate a labeled diagram of the shelf edge: label, in order from outside in at the moment of touching, (being shed), MEE, the forming MES at the , and . Then write one sentence explaining why the periderm has to go first, and add to Mateo's chart: "Act 3 begins, shelves adhere into a seam."
- 5Check it against the rubric, then submit.
| 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 the right way (Schoology for routine work) and confirmed. | Turned in, but in the wrong place or unconfirmed. | Not turned in. |
- CompleteProficient: Nothing is left blank: the model fills every part of "Annotate a labeled tissue diagram of the shelf edge: label, in order from outside in at the moment of touching, periderm (being shed), MEE, the forming MES at the midline, and mesenchyme. Then write one sentence explaining why the periderm has to go first, and add to Mateo's chart: "Act 3 begins, shelves adhere into a seam."".
- 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 turned in on Schoology and confirmed.
WebXam problem for today's skill
One exam-style question that uses exactly what you practiced today. Try it before you reveal the answer, then read why each choice is right or wrong.
Tap an answer to see the full explanation. Nothing is recorded or graded.