Question

What would be $\mathop \varphi \nolimits_P$ of a flaccid cell?

Answer 1

All living organisms, including plants, require free energy to grow and reproduce. In thermodynamics, free energy represents the potential to do work. The free energy of water is referred to as water potential. It is represented by the symbol $\mathop \varphi \nolimits_P$.

Complete answer:
Flaccid cell is defined as the cell which is placed inside the isotonic solution that is concentrated inside and outside the cell are exactly the same. So, the cell will not swell and not shrink.
In this kind of cell solute potential will be exactly equals to that of the water potential and hence turgor pressure will not present.
Its pressure potential will be the same at both the sides and no turgor pressure will be present in it. So, its water potential will be zero. This can be defined as follows:
By standard conditions the water potential of pure water at standard temperatures, which is not under any pressure, is taken to be zero.
When some amount of solute is dissolved in pure water, the solution now becomes deficient of free water and the concentration of water decreases, reducing its water potential.
Hence, all solutions have a water potential lower than that of a pure water; the magnitude of lowering of water potential due to dissolution of a solute is called solute potential or
All living organisms, including plants, require free energy to grow and reproduce. In thermodynamics, free energy represents the potential to do work.
The free energy of water is referred to as water potential. It is represented by the symbol $\mathop \varphi \nolimits_S$.
$\mathop \varphi \nolimits_S$ is always negative. The presence of more number of solute molecules means , the lower is the solute potential (more negative) is the $\mathop \varphi \nolimits_S$.
For a solution at atmospheric pressure (water potential) $\mathop \varphi \nolimits_W$ = (solute potential) $\mathop \varphi \nolimits_W$, If the pressure greater than atmospheric pressure is applied to pure water or a solution, its water potential increases.

Note:
Water potential is also defined as the potential of water that is chemical in nature means chemical potential. The greater the concentrations of water in a system, the greater is its kinetic energy or water potential'. Water moves from the point where water potential is greater, to the other point where water potential is less. It can also be said that the difference in water potential between two points is a measure of the amount of work (energy) needed to move water from one point to another.