Question

Why plant cells strings when kept in hypertonic solution

Answer 1

First ,that shrink not strings
And answer is that due to osmosis solvent moves out of cell where it's conc. Is lower.that is hypertonic solution

Answer 2

This happens due to osmosis.
When there is difference between con concentrations of two media, seperated by a semipermeable membrane such as plasma membrane, osmosis occurs.
In case of osmosis molecules of solvent move from higher concentration to lower concentration.
In case of hypertonic solition, the solution is stronger than that inside the cell.
So EXOSMOSIS takes place in which solvent particles inside the cell are given out which results in cell to become shrinked or flaccid.