Educator's Guide (Grades 9-12) - Buffalo Museum of Science
Educator's Guide (Grades 9-12) - Buffalo Museum of Science
Educator's Guide (Grades 9-12) - Buffalo Museum of Science
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EXPERIMENT:<br />
Test for the by-products <strong>of</strong> starch<br />
Materials:<br />
Starch, α-amylase, pancreatin, Fehling’s solutions I and II, test tubes.<br />
Preparation:<br />
I. Starch solution : see above, Preparation no. I<br />
II. Pancreatin solution: dissolve 1 “spoon tip’s worth ” <strong>of</strong> pancreatin in approx. 5ml water.<br />
III. Fehling’s reagent: see above, Preparation no. III<br />
Method:<br />
Mix the starch solution (I) with 1-2ml <strong>of</strong> pancreatin solution or saliva, as appropriate, and leave for a few<br />
minutes to react. Then carry out the Fehling’s test (see glucose test).<br />
Observations:<br />
The Fehling’s test is positive.<br />
Explanation:<br />
Pure starch solution does not reduce Fehling’s reagent (cf control experiment). Under the influence <strong>of</strong><br />
amylase, starch is broken down to maltose, which causes the typical Fehling’s reaction.<br />
Note:<br />
To show that the pancreatin preparation is sugar-free, you can carry out the Fehling’ s test with the<br />
remainder <strong>of</strong> the solutions. They should not cause the typical change in the reagent.<br />
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