Week 03 Lab Sheet: Plasma Membrane Transport
Introduction
This week’s lab will cover the concept of plasma membrane (cell membrane) transport, specifically osmosis, which is a special form of diffusion. Plasma membrane transport is a vital function of all cells and is a necessary foundational concept to understand.
Objectives
Objectives for this week’s lab include: 1) learning the difference between active and passive transport mechanisms, 2) see how solute concentration affects the movement of water, and 3) be able to describe the process of osmosis and diffusion along with the factors that affect it.
Overview
This lab takes a closer look at osmosis (a special form of diffusion) within a simulated cell. Diffusion is the passive movement of molecules from an area of high to low concentration. For example, let’s say you’re baking a loaf of bread in your kitchen. As it bakes, it releases odor molecules. Those odor molecules slowly diffuse from the kitchen (high concentration) throughout other areas of your home, like the upstairs (low concentration). It doesn’t take energy for these odor molecules to move from an area of high to low concentration- making it passive transport. Active transport is when molecules are moved from an area of low to high concentration requiring energy to do so.

Osmosis is a special form of diffusion in that it only pertains to the movement of water molecules from a high to low concentration across a semi-permeable barrier. The cell’s plasma membrane is a semi-permeable