Rate of Osmosis - Concentration free essay sample

A simple heading referring to your investigation Abstract: Write this section last! It is a brief paragraph or 2 which outlines the purpose, the method, the pattern of results and the conclusion you reached. It is an overall snapshot of the whole investigation. Introduction: Purpose: Biological Background: All living organisms are made of cells which are surrounded by a membrane. The cell membrane has many functions but the major function is regulating the passage of materials going in and coming out of the cell. These materials consist of sugars, salts, water and dissolved gases. Most materials move by simple diffusion from high concentration to low concentration. Some substances may be actively transported, which requires energy. The diffusion of water across a semi-permeable membrane is called osmosis. Osmosis is the net movement of molecules through a semi-permeable [1] membrane from an area of low solute concentration to an area with a high solute concentration. We will write a custom essay sample on Rate of Osmosis Concentration or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page In this investigation, we are testing how concentration effects the rate of osmosis Hypothesis: The more hypertonic potato pieces are to a saline solution, the more weight the potato will gain. However, the potato pieces will decrease in weight when they are placed in a hypotonic solution. Dependent variables: †¢Change in mass of pieces of potatoes. Independent variables: †¢solutions sucrose concentrations. Controlled variables: †¢amount of time in the solutions †¢surface area of the potato segments Factors held constant: Identify and follow with a prediction/s about the results expected to either support or not support the hypothesis Materials and method Materials: †¢2 large potatoes †¢Spoon †¢Ruler †¢3 x 250 mL beakers †¢Knife †¢Paper towel †¢NaCl solution (1% and 10%) †¢Electronic balance †¢Distilled water Method 1. Peel the potatoes and cut into 2cm3 cubes 2. Label the cubes of potato with the numbers 1 through to 6 3. Weigh each of the labeled cubes and record their â€Å"before† mass 4. In the beaker with 200mL of distilled water, place two cubes in and start the timer 5. When one minute has passed, in the beaker with 200mL of NaCl with a concentration of 2% place two cubes 6. When two minutes have passed, in the beaker with 200mL of NaCl with a concentration of 10% place two cubes in 7. After the cubes have been sitting in the solution for twenty minutes, remove and place onto paper towel. 8. Proceed to weigh the cubes once again and record their â€Å"after† mass Safety Assessment Possible Hazard Hazard assessmentSuggested safe operating procedure Knife High†¢Safe workplace †¢ one person cutting at a time Glassware Low-med†¢Walk carefully