Neco 2018 Biology Question 4

A halophytic plant growing in soil where the external NaCl concentration is 200\,mM accumulates the following solutes in its vacuoles: Na\(^+\) 150\,mM, K\(^+\) 50\,mM, and non‑ionic organic solutes 100\,mM. Assuming that the internal Cl\(^-\) concentration equals the internal Na\(^+\) concentration for electroneutrality, calculate the vacuolar osmotic potential \(\Psi_s\) using \(\Psi_s = -C_{\text{total}}RT\) (where \(C_{\text{total}}\) is the total molar concentration of solute particles, \(R = 0.0831\)\,L\,bar\,K\(^{-1}\)\,mol\(^{-1}\), \(T = 298\)\,K). The plant's pressure potential \(\Psi_p\) is -0.5\,MPa. Determine the plant's overall water potential \(\Psi_w\) and state whether it is lower (more negative) than the soil water potential of -0.8\,MPa, thus allowing water uptake.