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Diffusion and Osmosis • Learning objectives: • Design an experiment to create models of living cells using dialysis tubing to explore diffusion. • Design an experiment to identify the concentrations of the sucrose solutions by measuring the percent mass change in potatoes( osmosis).
Think about theses questions • Will water move into or out of a plant cell if the cell has a higher water potential than the surrounding environment? • –What would happen if you applied saltwater to a plant? • – How does a plant cell control its internal (turgor) pressure? • – What factors can affect osmosis based on the videos you watched?
Diffusion labDesign your experiment to answer the following questions :What is moved back and forth ? And how do you know this?What are the factors affecting the rate of diffusion in your experiment?
What you need to do • Design your experiment to find the morality of solutions using osmosis. • Results should show table and graph . • Why are we using percent change is mass? • How do you find out the morality of potatoes using your results. • What other factors can you consider as variable to test your experiment?
Think out of the box • Use the principles of osmosis to explain how foods are preserved. For example, foods are prepared using high concentrations of salt or sugar (e.g., preserves, jams, jellies). • Evolution connection:paramecium and other protists that live in hypotonic environments have cell membranes that limit water uptake, while those living in isotonic environments have membranes that more permeable to water. What adaptations might have evolved in protists in hypertonic habitats such as Great Salt Lake? In habitats with changing salt concentration?
- Pickles may be preserved in brine, which is a 30% salt solution. How does this method of preservation prevent contamination by microorganisms? • - Glucose is a six-carbon sugar that diffuses slowly through artificial membranes. The cells lining the small intestine, however, rapidly move glucose from the gut into their cytoplasm. This occurs whether the gut concentrations of glucose are higher or lower than the glucose concentrations in intestinal cell cytoplasm. Using this information, which transport mechanism is most likely responsible for the glucose transport in intestinal cells? Why? • - While on a trip to the desert, a friend of yours was bitten by a rattlesnake. He nearly died from hemolysis, or breakage of many of his red blood cells. You have analyzed the snake venom and found three enzymes: phospholipase, which degrades phospholipids; neuraminidase, which removes cell surface carbohydrates; and protease which degrades proteins. Which of these enzymes do you think was responsible for his near fatal red blood cell hemolysis? Why? • - Ethanol, the active ingredient in alcoholic beverages, is a small, polar, and uncharged molecule. Would you predict that this molecule crosses cell membranes quickly or slowly? Explain your reasoning.
1-A4 paper typed report. • 2- Brochure ( post pictures of your experiment process) • 3 - Mini chart • 4- Videotaping with full explanation of the terms