a drop of a 5% solution of NaCl is added to a leaf of an aquatic plant. when the leaf is viewed under a microscope, colourless region appear ath the edges of each cell as the cell membrane shrinks from the cell walls. describe what is happening and why.

Question

blues · Answer

OK, this is a question about concentration gradients.

An aquatic plant is used to living in water, so the concentrations of molecules inside the cells are roughly equal to the concentrations of molecules in the pond water. The 5% NaCl has a much higher concentration of molecules than pond water...

Helpful?

blues · Answer

Think about what happens when two different compartments - in this case the inside of the leaf cells and the world around it - have different concentrations of a molecule. You get flow down the concentration gradient...

anonymous · Answer

so the plant will have a higher concentration than the pond water because of the NaCl ??

blues · Answer

No. The relative concentration of water molecules to other molecules is roughly the same inside the plant cell and the pond water. The NaCl has a much lower concentration of water and a much higher concentration of other molecules (namely, Na and Cl ions).

anonymous · Answer

okay this is like isotonic right? or am i wrong again

blues · Answer

That is exactly the right line of reasoning.

The plant cell is isotonic with the pond water. It is not isotonic with the NaCl solution - that is, there is a concentration gradient such that there is a much higher concentration of water molecules inside the leaf than in the NaCl solution. So all those water molecules flow down their concentration gradient. What does that do to the leaf?

anonymous · Answer

the leaf will shrink

blues · Answer

Exactly. The leaf cells will all shrink - but the cell walls are really stiff and won't bend. Which is what the question asks. Is it clear to you now?

anonymous · Answer

yes it is clear

anonymous · Answer

thank you so much

blues · Answer

All cool. Are you ready to go on to your other questions?

anonymous · Answer

yes ... i have posted it on the wall , if you could take a look on it .... it woulod really help me