Physiology

Analyzing tonicity with osmosis and the rate of diffusion through a permeable membrane.

Muraoka, Kara Lei

PHYL 141 L Section 004

Introduction:

In this lab, we are learning about tonicity through osmosis and the rate of diffusion. In the body we have semipermeable membrane that controls what can go in and out of the cell. Semipermeable is allowing some particles pass through the membrane more freely than others (Li). Diffusion is having molecules move through a higher concentration to a lower one. Osmosis involves water to move from a low concentration of solute to a high concentration (Marieb et al. 2015). Osmosis is a type of diffusion, therefore they are very similar and the outcome of their job is the same. They both bring the cell to a more stable energy state, eventually obtaining dynamic equilibrium. Diffusion and osmosis differ slightly because osmosis is specifically the diffusion of water, while diffusion can be any molecule that is trying stabilize their energy states. Also osmosis moves against the concentration gradient, while diffusion moves with the concentration gradient (Martini et al. 2015). This happens because osmosis is diluting the higher concentration to help the cell become more stable, while diffusion is molecules moving to the lower concentration to become more stable.

Various factors can affect the rate of diffusion. Concentration, size, temperature, surface area, and polarity are all examples that influence the rate of diffusion (Marieb et al. 2015). In this experiment we tested, concentration, size and temperature. The higher the concentration, the greater the rate of diffusion, therefore we tested two different concentrations at 2M and 4M. The smaller the particle size is, the quicker they are able to spread out and enter the membrane, so we tested 2M glucose and 2M sodium chloride. Lastly, the increase of temperature causes kinetic energy and collision, which then makes particle diffuse quicker (Marieb et al....