Hypotonic means less salute and more water. For this lab, we can apply these principles to plant cells. The plant cells have a semi permeable membrane so they can experience osmosis and diffusion as discussed earlier. When it comes to the potato cells, added with NaCl (salt) it will experience a reaction changing the form of the cells. The hypothesis of this experiment goes as follows, If we place potato cells in a salt solution, then the cells will shrink.
If we place the potato in a sucrose solution with a similar solute concentration as a potato, then the least amount of water will diffuse into or out of the potato cells. This occurs because this scenario will be initially closest to an isotonic solution, allowing us to determine the solute concentration of a potato. Materials: * Knife/ Cork Borer * Seven 30 cm pieces of Dialysis tubing * Thirteen 250 mL Beakers * 15% Glucose Solution * Glucose Test Strips * 1% Starch Solution * Distilled water * Lugol’s solution * 25 mL of: * .2 M sucrose * .4 M sucrose * .6 M sucrose * .8 M sucrose * 1 M sucrose * Paper Towels * Clock * Potatoes * Plastic
Diffusion Across a Plasma Membrane In order to demonstrate the way in which semipermeable membranes work, an experiment replicating the digestive system of a caterpillar was preformed. To simulate a semipermeable membrane dialysis tubing was used. It is capable of demonstrating the way in which a semipermeable membrane will allow only molecules under a certain size to pass through it. First, to simulate the crop of the caterpillar, a small beaker was filled with four pipettes worth of cooked starch as well as four pipettes worth of alpha amylase solution and stirred. The cooked starch acts as the food, which the caterpillar would eat, and the alpha amylase, which is a digestive enzyme common in saliva, is stirred with it to simulate the chewing and mixing of food and saliva which constitutes the first step in the digestive system.
Other tests also included in this experiment were testing for Sodium Bicarbonate, and Starch. For the testing of acids or bases I found that when mixed with Bromothymol Blue (BTB) acids would turn yellow and bases would remain blue. Starch tests were combining NaOCl and KI and when these two chemicals were combined it would turn black when encountering starch. I then tested this theory on certain foods to test for starch and found that a cracker and potato had a lot of starch. The test for Sodium Bicarbonate included mixing that with HCl.
Cody Baycroft Mrs. Vance AP Biology pd.3/6 7 October 2011 Effect of Solute Concentration on Water Potential Research Question: Investigate the concept of water potential in relation to the movement of water into or out of a plant cell (potato). This will be researched by immersing potato cores in sucrose solutions (0.0M, 0.2M, 0.4M, 0.6M, 0.8M, 1.0M) and determining the change in mass (in percent) of the cores. Hypothesis: If the solute concentration is increased, then the water potential of solution will have increasingly more negative values. In other words as the concentration of the sucrose solutions becomes more hypertonic than the potato core (the solution has greater solute concentration and lower water potential) the potato will begin to loose mass since water will leave the hypotonic potato core (the core has less solute concentration hence higher water potential) to the hypertonic solution in order to dissolve the sucrose solution. Water potential is the concept used to combine the differences in solute concentration and pressure to predict the direction in which water will diffuse through the living plant tissue and states that the net movement of water will always be from an area of higher water potential to and area of lower water potential.
Strategy For this coursework, I will be investigating the following question: ‘How do different concentrations of salt solutions affect the mass of the potato after the process of osmosis?’ Osmosis is the movement of water particles from a high concentration of water particles to a low concentration across a partially permeable membrane. A partially permeable membrane is a membrane that acts as a barrier to some molecules but allows others to freely diffuse through. The partially permeable membrane of cell membranes prevent large molecules such as Sucrose, protein and starch to pass through but allow smaller molecules such as oxygen, carbon dioxide and water, glucose and amino acids to proceed. In this coursework we will be using potato to test the rate of osmosis. If the area around a cell has a higher water concentration it will gain water by osmosis.
September17.2013 P.4 Environmental Sources Of Bacteria Purpose: We did this lab to find out exactly which conditions would help to grow a bacterium the best. Materials: • Agar • Petri dish • Cotton • Incubator • Tape • Bacteria Procedure: 1. Mark bottom of Petri dish 2. Split petri dish into 4 sections and label the sections 3. Pour hot agar into dish 4.
_______ Is a fat present? _____________________ Food Test: Circle the + or -- sign for each food after testing for the particular organic molecule. ***Remember a + color change indicates the presence of the particular organic molecule. | |Type of Organic Molecule | | |Simple Sugar |Starch |Protein |Fat | |Potato |color change? + -- | + -- | + -- | + -- | |Orange Juice | + -- | + -- | + -- | + --
Misner and Curtis (2008) talk about a research which shows that plastic cutting boards are nonporous and therefore easier to clean and safer for cutting meat and poultry. Although wooden boards have antimicrobial qualities, they are porous and bacteria can become trapped in these surfaces and do not come off easily when rinsing. Because bacteria can live in a dormant state for a long time, they can contaminate foods when you use the wooden boards at different times. Even though plastic boards contain bacteria as well, they can be more easily washed off making plastic cutting boards the better option. 2.
Osmotic pressure is colligative properties (which are properties of solutions that depend upon the ratio of the number of solute particles to the number of solvent molecules in a solution (Chemistry). Osmosis is essential in biological systems. The aim for this lab report is to assess the effect of weight and length of 5 different concentrations of a salt solution on 6 different potato wedges over 24 hours. To do this we will research how the effect of different salt solution concentrations will have an affect on 6cm length potato wedges. Research Question: How will the different potato wedges submerged in various salt solutions affect on the weight and length of the potato wedges?