1.2.8 Lab_ Osmosis, Diffusion, and the Effects on Transpiration

1.1 1. What environmental factors affect kinetic energy and diffusion? Temperature, air pressure 2. Why do these environmental factors alter diffusion rates? How do they affect rates? If the temperature changes, the energy gained or lost changes as heat is absorbed or lost by the molecules. If temperature is increased, then diffusion rate increases, and vice versa. Also, more pressure means more molecules collide with each other, and vice versa. 3. How are gradients important in diffusion and osmosis? Diffusion occurs when there is a gradient, so that concentrations can be distributed evenly to other parts. Without a gradient, there would be no movement from high concentration to low concentration. Gradient is necessary for diffusion and osmosis to occur. 4. What is the explanation for the fact that most cells are small and have cell membranes with many convolutions? Smaller cells have more surface area:volume ratio, allowing more substances to be diffused into and out of the cell. Convolutions increase the surface area, increasing the rate of diffusion. 5. Will water move into or out of a plant cell if the cell has a higher water potential than the surrounding environment? Out 6. What would happen if you applied saltwater to a plant? Saltwater draws water out of the plant cell, causing the plant to shrivel. 7. How does a plant cell control its internal (turgor) pressure? The glucose changes in the plant results in water potential, changing the gradient of glucose concentration to control turgor pressure. 8. What factors, including environmental variables, affect the rate of transpiration in plants? Temperature, pH of soil, air quality, humidity, amount of sunlight 9. If a plant has a lower water potential than its surrounding environment, make a prediction about the movement of water across the cell membrane. In other words, will the cell gain water or lose water? The high water potential outside the cell causes water to move into the plant cell to reach equilibrium, so the cell gains water. 10. In the winter, salt is sometimes spread over icy roads. In the spring, after the ice has melted, grass often dies near these roads. What causes this to happen? The salt changes the environment to a hypertonic environment, causing the water to leave the cells. The plants die due to lack of water.