AP BIOLOGY Daily Agenda: Quiz: Plasma Membrane & 2.7 Tonicity and Osmoregulation

Tuesday, October 14, 2025

Explain how osmoregulatory mechanisms contribute to the health and survival of organisms.

Tasks:


1	Quiz: Plasma Membrane
2	Sample Problems Try the sample problems after the quiz. a) What is the water potential (ψ) of a plant root cell placed in distilled water (0 bars) and has a pressure potential of -2.5 bars? b) A plant cell is placed in a solution where the water potential (ψ) is -1.2 bars. Inside the cell, the solute potential (ψ_s) is -2.0 bars and the pressure potential (ψ_p) is 1.0 bars. Calculate the water potential inside the cell. Determine the direction of net water movement between the cell and the solution. c) During a hot, dry day, a plant experiences high rates of evapotranspiration. The water potential in the leaf cells is measured at − 3.5 bars due to water loss. The soil water potential is −0.8 bars, and the pressure potential in the root cells is 1.2 bars. Calculate the solute potential in the root cells. Explain how the difference in water potential between the soil, the leaf cells, and the atmosphere drives the movement of water through the plant during transpiration.
3	Friday Recap “Osmoregulation” & Try Sample Problems #2 & 3 Continue with the slides from the previous class. We finished sample problem #1 (page 5). Now, let’s explore problems #2 & 3.
4	Simulation: Water Potential Equation Let’s try a simulation looking at water potential. Simulation Link
5	Worksheet Use the worksheet to try some water potential problems. Worksheet Formula Sheet