Schoolwork123
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Does anyone know how I should answer this? Any help/suggestions would be greatly appreciated.

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An investigation was carried out to estimate the water concentration of red onion epidermal cells. Pieces of epidermis were covered with a drop of salt solution on a microscope slide. After 5 minutes, the number of plasmolysed cells in a count of 50, in three different areas of the slide, were counted.

This was repeated with other salt concentrations.

The results are shown in the table.

Concentration of salt solution (M)
0
0.05
0.1
0.15
0.2
0.25

Average percentage of plasmolysed cells (%)
0
20
40
60
80
100


Q. Give evidence that supports the statement that water concentration varies amongst the red onion epidermal cells.

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P.S. Don't know how to make a table, so made the results as a kind of list. 0 from "Concentration of salt solution (M)" column corresponds with 0 from "Average percentage of plasmolysed cells (%)" column and so on.
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Nessie162
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Have a think about what would happen if all the cells had the same water concentration.

If all cells were the same, the percentage of plasmolysed cells would always be either 0% or a 100% (depending on the salt concentration).
Why? Because the salt would have the same effect on ALL the cells (After all why would it have a different effect if the cells were all identical).
For the salt not to have the same effect on all the cells at lower concentration, they have to differ in some way.

Think of the salt concentration as a "strength" of pulling the water of out of the cell.
Let me know if you need me to illustrate it.
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Schoolwork123
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(Original post by Nessie162)
Have a think about what would happen if all the cells had the same water concentration.

If all cells were the same, the percentage of plasmolysed cells would always be either 0% or a 100% (depending on the salt concentration).
Why? Because the salt would have the same effect on ALL the cells (After all why would it have a different effect if the cells were all identical).
For the salt not to have the same effect on all the cells at lower concentration, they have to differ in some way.

Think of the salt concentration as a "strength" of pulling the water of out of the cell.
Let me know if you need me to illustrate it.
Thank you for your response! That makes a lot of sense. I had thought about that as a possible answer, so it's good to have that validation.
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