AP BIO
AP Bio Essay #1
To address this problem created by the lab tech, I would set up an experiment like the one we did in AP biology to identify the molarity of the unknown sucrose solutions. First I would pour an equal volume of each solution into beakers labeled A, B, C, and D. I would also have a beaker of the same amount of distilled water to serve as a control for the experiment. Then I would obtain several baby carrots, 4 per beaker. I would mass the groups of 4 potatoes before placing them in their respective beakers of solution. potatoes do have semipermeable cell membranes (water should be able to pass, but not necessarily the larger sucrose), but in order to allow materials to pass through the carrots and be able to measure a change I would let the potatoes sit overnight (or at least for several hours after placing them in the solutions). Upon returning to the lab, I would extract the carrots from their solutions, blot them dry, mass them again, and then calculate the percent change in mass of the carrots after sitting in solution. I would expect that the carrots in water as well as possibly the 0.2 M sucrose would gain mass. The potatoes in 0.4 M, 0.6M and 0.8M sucrose solution should show greater percentage mass loss with each increasing concentration of sucrose in solution. The results seen in the water control as well as possibly the 0.2M sucrose occur because the water potential outside of the potatoes would be higher thus encouraging water to move into the potatoes and increase their mass. In other words, osmosis (diffusion of water from high to low concentration across a membrane) occurred and moved water from the environment hypotonic to the carrot into the carrot itself in an attempt to equalize concentration between them. In the higher molarity sucrose solutions, water’s potential is higher inside the potatoes—the water content of the carrots is more pure than in the outside solutions. Thus water would move out of the carrots into the
To address this problem created by the lab tech, I would set up an experiment like the one we did in AP biology to identify the molarity of the unknown sucrose solutions. First I would pour an equal volume of each solution into beakers labeled A, B, C, and D. I would also have a beaker of the same amount of distilled water to serve as a control for the experiment. Then I would obtain several baby carrots, 4 per beaker. I would mass the groups of 4 potatoes before placing them in their respective beakers of solution. potatoes do have semipermeable cell membranes (water should be able to pass, but not necessarily the larger sucrose), but in order to allow materials to pass through the carrots and be able to measure a change I would let the potatoes sit overnight (or at least for several hours after placing them in the solutions). Upon returning to the lab, I would extract the carrots from their solutions, blot them dry, mass them again, and then calculate the percent change in mass of the carrots after sitting in solution. I would expect that the carrots in water as well as possibly the 0.2 M sucrose would gain mass. The potatoes in 0.4 M, 0.6M and 0.8M sucrose solution should show greater percentage mass loss with each increasing concentration of sucrose in solution. The results seen in the water control as well as possibly the 0.2M sucrose occur because the water potential outside of the potatoes would be higher thus encouraging water to move into the potatoes and increase their mass. In other words, osmosis (diffusion of water from high to low concentration across a membrane) occurred and moved water from the environment hypotonic to the carrot into the carrot itself in an attempt to equalize concentration between them. In the higher molarity sucrose solutions, water’s potential is higher inside the potatoes—the water content of the carrots is more pure than in the outside solutions. Thus water would move out of the carrots into the