Agar Cube Experiment

2664 Words11 Pages
DIFUSSION IN AGAR CUBES – LAB REPORT Research question What is the effect of surface area on volume ratio on the rate of diffusion of pigment from the agar cube measured by percentage volume of diffusion over time? Background Diffusion is a process of spontaneous spreading of particles in an environment (e.g. a cell), which is a consequence of chaotic collisions of molecules of the diffusing substances with each other or with the molecules of the surrounding environment. It can be observed in cells when substances e.g. water, oxygen, nutrients, cellular waste are transported inside, outside the cell or to different cellular organelles. It is easy to observe diffusion by gently pouring a coloured liquid into water. In this experiment I will examine diffusion of a solution in a jelly-like substance - agar. Because both the solution and the agar are colourless I will use agar that had before been mixed with phenolphthalein. This also colourless substance is a commonly used indicator that changes its colour into pink with the presence of a base. It will turn pink immediately when mixed with a NaOH solution. When the agar-phenolphthalein cubes will be put into the sodium hydroxide solution, NaOH will start diffusing through the agar cubes and turn the inside of the cube pink gradually. We want to examine whether ad how the rate of diffusion over time is dependent on the cubes surface area to volume ratio (SA:V). Smaller cubes have bigger SA:V than big cubes. We know that e.g. cells seek to have the biggest surface area possible and a small volume. We will therefore see, whether one of the reasons they do it is the rate of diffusion. Hypothesis If a big surface area to volume ratio is something very desired by cells that need efficient and fast diffusion for their functioning (transporting nutrients, oxygen, water, waste), then the greater the SA:V,

More about Agar Cube Experiment

Open Document