Cell Membranes - Clued Corrections
How do biomolecules move across the cell membrane?
The following statements are examples of “Claims” from the Cell Membrane Explanation. Not all of these statements received full credit for their work.
- Help these students complete their claims by deciding which responses:
- Received full credit, no corrections (3 students)
- Received no credit because their claim was vague or not correct. (5 students)
- If the claim was unclear, rewrite the statement so it would receive full credit.
Reasoning Statement / Notes on why it is correct or Re-write
1 / The cell is semi-permeable it did not let in protein and did not let in starch.
2 / Large moleculescannotmove across the cellmembranebut small biomolecules can.
3 / I think that some cells pass through the cell membrane because they are smaller and can fit through the spaces in the membrane.
4 / Smaller molecules can easily slip in and out of the membrane.
5 / Biomolecules pass through the membrane through diffusion.
6 / Bigger molecules (protein, fat and starch) cannot pass throughthecellmembranebut smaller molecules (iodine and glucose) can pass through the membrane.
7 / Protein did not pass through the membrane and neither did the starch but glucose did.
8 / Membranes are selectively permeableby size, they allow small molecules through but not large molecules. / [FJ1]
What do you need to be sure to do to receive full credit for your claims?
Teacher Notes:
Reasoning Statement / Notes/Re-write1 / The cell is semi-permeable it did not let in protein and did not let in starch. / No mention of what it does let in and what the trend is.
2 / Large moleculescannotmove across the cellmembranebut small biomolecules can. / Correct
3 / I think that some cells pass through the cell membrane because they are smaller and can fit through the spaces in the membrane. / Does not mention or compare to large molecules
4 / Smaller molecules can easily slip in and out of the membrane. / Does not mention large molecules
5 / Biomolecules pass through the membrane through diffusion. / Does not explain how/why some molecules pass through and some don’t.
6 / Bigger molecules (protein, fat and starch) cannot pass throughthecellmembranebut smaller molecules (iodine and glucose) can pass through the membrane. / Correct
7 / Protein did not pass through the membrane and neither did the starch but glucose did. / Does not inform general trend of biomolecules movement across membrane due to size.
8 / Membranes are selectively permeableby size, they allow small molecules through but not large molecules. / Correct
[FJ1]