Transport in Plants — BIOLOGY STD 11 Science — Question
Gujarat BoardEnglish MediumSTD 11 ScienceBIOLOGYTransport in Plants5 Marks
Question
Briefly describe water potential. What are the factors affecting it?
✓
Answer
Water potential is the difference in the free energy or chemical potential per unit molal volume of water in a system and that of pure water at the same temperature and pressure. It is the tendency of water to move from one area to another due to osmosis, gravity, mechanical pressure, matrix effects and surface tension. It is measured in units of pressure and is represented by the Greek letter $\Psi$ (Psi). Pure water at standard temperature and pressure is defined as having a water potential of 0. The addition of solutes to water lowers its potential, whereas the increase in pressure increases its potential. Example: Sea water or the solution within living cells hasnegative water potentials as compared to pure water. If two systems having water are in contact, more random movement of water molecules in the system having higher water potential or more energy will result in their net movement towards the system with low energy or low water potential. The following factors affect water potential:
Solute potential $\left(\Psi_s\right)$.
Pressure potential $\left(\Psi_p\right)$.
Matric potential.
Temperature.
Pressure.
Loss or gain of water.
Need a full question paper?
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.