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Design an experiment to investigate how the water potential of bananas alters as they ripen over time.

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Introduction

Sasha Caddy, 16/11/03 RM11. The Ripening Banana Challenge The Problem It was noticed that as bananas ripen the sweeter they taste. A possible explanation for this is that as they ripen some of the starch that they contain is hydrolysed to form sugars. The Task Design an experiment to investigate how the water potential of bananas alters as they ripen over time. Water potential is a measure of the tendency of water molecules being absorbed into a solution by osmosis. Osmosis is the net movement of water through a partially permeable membrane from a solution of a less negative water potential to a solution of a more negative water potential. In this experiment I need to determine the affect of a range of solutions of different concentrations that alters the ripening of the banana. Materials: * Scalpel or knife. * 6 petri dishes. * 5 boiling tubes. * Boiling tube rack. * 2 x 10cm or 25cm graduated pipette. * Pye pump. * Thermometer. ...read more.

Middle

These controlled variables will ensure that each result is accurate and reliable. Method: 1) Label six petri dishes appropriately, one for each of the following different molars of sucrose solution: 1.0M, 0.8M, 0.6M, 0.4M, 0.2M and distilled water. Also label five boiling tubes appropriately, again one for each of the sucrose solutions. 2) Using a graduated pipette (2 x 10cm or 25cm ), two beakers (2 x 100cm ), one beaker of distilled water and one beaker of 1M sucrose solution, make up 20cm of sucrose solution of the required concentration in each boiling tube, which are: * 1.0M solution - 20cm of 1M sucrose solution. * 0.8M solution - 16cm of sucrose and 4cm of distilled water. * 0.6M solution - 12cm of sucrose and 8cm of distilled water. * 0.4M solution - 8cm of sucrose and 12cm of distilled water. * 0.2M solution - 4cm of sucrose and 16cm of distilled water. ...read more.

Conclusion

9) Next calculate the percentage change of each concentration, using the following calculation: Change (cm) x 100% = Percentage Change in length (%) Original (cm) 10) Repeat the whole experiment at least three times keeping the independent variables, dependent variables and the controlled variables the same to ensure accurate and reliable results. From the results I will be able to determine how the water potential of bananas alters as they ripen over time. If I discover at one of the concentrations there is no change in length then the water potential of the banana hasn't changed so it is still at the same stage of ripeness as it was at the beginning of the experiment. Meaning some of the starch from the banana has not hydrolysed to form sugars. If the length of each square segment has a percentage decrease then it has ripened, which means some of the starch that the banana contains has been hydrolysed to form sugars, so therefore has become sweeter in taste. ...read more.

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