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Posted

Samples of potato tissue placed in a salt solution overnight and changes in weight indicates that the cells took up water.

 

 

 

 

 

What is the conext of this? A slice of potato under a microscope? Generally within a whole potato plant?

Posted (edited)

Because dead cells have no energy to expend to carry out osmosis.

It doesn't require energy.

 

Edit: that's wrong, it requires potential energy I guess. No energy on the part of the cell.

Edited by Brainteaserfan
  • 3 weeks later...
Posted

Osmosis, simply put, is just the diffusion of water molecules. Just like diffusion, it requires no energy from ATP, it is not a metabolic process like active transport (transfer of molecules AGAINST a potential gradient). However, dead potato cells still have cell walls and cell membranes, hence, osmosis, transfer of water molecules still occurs between cells. For instance- from 0kPa to -4000kPa. within plant cells.

 

It is just a process like diffusion, to attain an equilibrium, so no energy is required, all follows the flow of a higher water potential to one of lower water potential (across a potential gradient)

Because dead cells have no energy to expend to carry out osmosis.

  • 3 months later...
Posted (edited)

why does osmosis occur in dead potato cells.?

Osmosis envolves automatic physical reactions at a molecular level, and therefore, it does not cosume energy from the cell. If the cells are dead (not producing energy anymore) but if they are relatively fresh and if they are not dry (and 80% of a potatoe is water), I suppose osmosis continues to occur. The passage of water molecules though the cell membrane(osmosis) occurs directly due to channel proteins that cross that membrane. If a cell contains water, there is no obvious reason why it should not keep its structure. So, if the structure is intact, as long as there is not a isotonic balance, osmosis should continue happening, to achieve that same balance (in most plant cells, such as potato cells).

Isotonic balance is when the density (of solute) outside and inside the cell is the same. Plant cells tend to achieve this. To achieve this, the cells loses or gets water (osmosis), and loses or gets solute (difusion). The movements of matter occur by phsical priciples that require mixing intracellular and extracellulr solutions to achieve balance.

*I assume that you talking about an experiment with a microscope...

Thank you.

Edited by Gonçalo Ferreira

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