How the Palate Begins: Secondary Palatal Shelf Outgrowth
Developmental domain · Lesson 6 of 20 · Principles of Biomedical Science (PBS)
Today's goal: Explain that the secondary palate begins as two shelves that grow downward from the maxillary processes, and that their growth depends on cell proliferation driven by signals in the mesenchyme.
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.
Act 1: Growth. The secondary palate begins as two shelves that bud from the maxillary processes at about week 6 and grow vertically (downward) beside the tongue. They are made of neural-crest-derived mesenchyme and reach full size by proliferation (cell division). One reason a shelf might end up too small: a missing growth signal, like in the Msx1 mouse, where too few dividing cells left the shelf too small and the palate cleft (a Bmp4 add-back rescued it).
Evidence call for Mateo: keep open. A growth failure is one hypothesis on the table, not confirmed; we have not ruled anything in or out yet.
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: Where does the back of the come from, and what makes it grow?
- 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: Write the "Act 1: Growth" entry for Mateo's developmental chart in plain language: where the shelves start, which direction they grow, and one reason a shelf might end up too small. Then mark whether there is enough evidence yet to say a growth failure is what happened to Mateo, or whether it is one hypothesis to keep on the table.
- 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 "Write the "Act 1: Growth" entry for Mateo's developmental chart in plain language: where the shelves start, which direction they grow, and one reason a shelf might end up too small. Then mark whether there is enough evidence yet to say a growth failure is what happened to Mateo, or whether it is one hypothesis to keep on the table.".
- 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.