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Biology LibreTexts

3: Digestion

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  • By Dr. Ingrid Waldron, Department of Biology, University of Pennsylvania, CC-BY-NC 4.0.


    The Student Handout provides information and questions to guide students in designing the first experiment which evaluates two indicator solutions to see whether they can be used to test for starch and/or for protein. Then, students will use the results from the first experiment and inductive reasoning to formulate hypotheses concerning which types of food contain starch and which types of food contain protein (some or all foods derived from animals or plants or both). Next, students can use deductive reasoning based on their hypotheses to make predictions for a second experiment to test their hypotheses. Finally, students will carry out the second experiment and use the results to evaluate their hypotheses and, if necessary, modify these hypotheses.


    Alternatively, the experiment could also be used in the BI 101 sequence as part of the intro to chemistry.

    • 3.1: Starch Protein Protocol
      An indicator solution is a good test for starch if it changes color in the presence of starch but does not show the same color change in the presence of other molecules such as proteins, lipids, or sugars. You will be given two indicator solutions to evaluate whether either of these indicator solutions can be used to test for starch. You will also evaluate whether either of these indicator solutions can be used to test for proteins.
    • 3.2: Starch Protein Teacher's Preparation Notes
      In this activity, students learn about the scientific method by carrying out key components of a scientific investigation, including the development of experimental methods, the generation of hypotheses, the procedures of the experiments to test these hypotheses, and the utilization of experimental results to revise these hypotheses.