You will use two tests in your experiment:
1. I 2 KI test for presence of starch. When I 2 KI is added to the unknown solution, the solution turns purple or black if starch is present. If no starch is present, the solution remains a pale yellow-amber color.
2 . Benedictâs test for reducing sugar. When Benedictâs reagent is added to the unknown solution and the solution is heated, the solution turns green, orange, or orange-red if a reducing sugar is present (the color indicates the sugar concentration). If no reducing sugar is present, the solution remains the color of Benedictâs reagent (blue).
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Hypothesis Hypothesize about the selective permeability of dialysis tubing to the substances being tested.
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Prediction Predict the results of the I 2 KI and Benedictâs tests based on your hypothesis (if/then).
....?
You will use two tests in your experiment:
1. I 2 KI test for presence of starch. When I 2 KI is added to the unknown solution, the solution turns purple or black if starch is present. If no starch is present, the solution remains a pale yellow-amber color.
2 . Benedictâs test for reducing sugar. When Benedictâs reagent is added to the unknown solution and the solution is heated, the solution turns green, orange, or orange-red if a reducing sugar is present (the color indicates the sugar concentration). If no reducing sugar is present, the solution remains the color of Benedictâs reagent (blue).
---
Hypothesis Hypothesize about the selective permeability of dialysis tubing to the substances being tested.
... ?
Prediction Predict the results of the I 2 KI and Benedictâs tests based on your hypothesis (if/then).
....?
Related textbook solutions
Related questions
Table 1: Testing for Proteins Results | |||
Sample | Initial Color | Final Color | Protein Present |
1 - Albumin Solution | |||
2 - Gelatin Solution | |||
3 - Glucose | |||
4 - Water | |||
5 - Unknown | |||
Post-Lab Questions
- Record your hypothesis about what will happen when Biuretsolution is mixed with the solutions from test tubes 1, 2, 3, and 4here. Be sure to use scientific reasoning to support yourhypothesis.
- Write a statement to explain the molecular composition of theunknown solution based on the results obtained during testing withthe Biuret solution and each sample solution.
- Diet and nutrition are closely linked to the study ofbiomolecules. How should you monitor your food intake to insure thecells in your body have the materials necessary to function?
- There are other types of reagents used to determine what typeof biomolecule a substance is. For example, copper ions present inBenedictâs reagent reacts with the free end of any reducing sugars,such as glucose, when heated. Originally blue in color, thesecopper ions are reduced by the sugar, and produce an orange-redcolored precipitate. Alternatively, iodine-potassium iodide (IKI)may also be used when working with starch. IKI contains specialtri-iodine ions which interact with the coiled structure of astarch polymer. Prior to a reaction, the IKI displays ayellow-brown color; however, after reacting with starch, a darkpurple or black color is presented.
The molecule pictured below produced ablue color when tested with Benedictâs reagent, a yellow color whentested with IKI, and a violet color when tested with Biuretreagent. Based on the structure shown below and these chemicalresults, what kind of biomolecule is this?
