If a cell with incipient plasmolysis is placed in a hypertonic solution,it will show:

Read the given statements regarding the different stages of plasmolysis and choose the correct option.
$I.$ First stage of plasmolysis,when osmotic concentration of cell sap is just equivalent to that of external solution.
$II.$ Protoplast withdraws itself from the corners of the cell wall.
$III.$ Protoplast gets detached from the cell wall and attains a spherical shape.

Which one of the following denotes the water potential of the mesophyll cell in a wilted condition?

If the external solution is less concentrated than the cytoplasm,it is called $P$. If the external solution is more concentrated than the cytoplasm,it is called $Q$. If the external solution balances the osmotic pressure of the cytoplasm,it is called $R$.

When a plant dies due to the application of excessive fertilizer,the reason is that the fertilizer causes:

When a freshly collected $Spirogyra$ filament is kept in a $10\%$ potassium nitrate solution,it is observed that the protoplasm shrinks in size.
$(a)$ What is this phenomenon called?
$(b)$ What will happen if the filament is replaced in distilled water?