To initiate cell plasmolysis, the salt concentration must be :
The most accepted theory for stomatal opening and closing is :
2. guard cell photosynthesis
3. K+ efflux and influx
4. starch glucose interconversion.
Ascent of sap is mainly attributed to :
1. cohesion force
3. root pressure
Water lost by transpiration is :
1. rich in solutes
2. rich in dissolved roots
3. rich in dissolved minerals
4. pure water.
Main function of lenticels is :
3. gaseous exchange
Solution concentration is higher in the external solution. The solution is
4. None of the above.
In CAM plants, stomata are :
1. always open
2. never open
3. open during day and close at night
4. open during night and close during the day.
Wilting occurs when there is :
1. transpiration higher than absorption
2. absorption higher than transpiration
3. high relative humidity of atmosphere
4. excessive root pressure.
Which one is responsible for opening and closing of stomata :
1. Rise in pH of guard cells, hydrolysis of starch
2. Cytolinins and CAMP required
3. Abscisic acid promotes closure
4. All the above.
A plant cell becomes tugid due to :