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 :
Potometer works on the principle of :
1. Amount of water absorbed equals the amount transpired
2. Osmotic pressure
3. Root pressure
4. Potential difference between the tip of the tube and that of the plant.
Which of the following in guard cell is responsible for opening of stomata?
1. decrease in concentration and more ion
2. decrease in concentration and less ion concentration
3. increase in concentration and more ion concentration
4. More free ion and less ion.
Passive adsorption of water by the root system is the result of
1. Forces created in the cells of the root
2. increased respiatory activity in root cells
3. tension on the cell sap due to transpiration.
4. osmotic force in the shoot system.
Water is lost in a liquid state in some plants through hydathodes. These hydathodes
1. remain closed at night
2. remain closed during day
3. remain always open
4. do not show any specificity in opening and closing.