Tag: iodine
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Macromolecules Lab – Testing for Starch
Most biology textbooks have a chapter on macromolecules. In chapter 2 of our textbook, students learn about the chemistry of life, which includes the basics of atoms and molecules, properties of water, and carbon compounds. I generally include a food testing lab where students determine the macromolecules found in food. The lesson is engaging, informative,…
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Investigation: Bananas, Starch, and Plastids
Explore the differences between ripe and green bananas in the activity. Green banana cells will have large dark starch granules when stained with iodine.
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Virtual Diffusion Lab
The diffusion lab has been a yearly activity in my biology class as part of a unit on cells and cell transport. Students fill a bag with starch and water and then submerge it in a solution of iodine and observe what happens. The iodine diffuses across the plastic bag and turns the starch purple.…
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Investigation: How Can Diffusion Be Observed?
This investigation provides a hands-on way to observe what happens when a chemical moves across a semipermeable membrane. In this case, a cheap plastic bag serves as a model for the cell membrane and shows that iodine will move into the bag and turn the contents purple.
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Investigation: Observing Diffusion & Semi-Permeable Membranes
Units on the cell will also include lessons about how the cell transports materials across the membrane. For beginning biology students who don’t have a strong foundation in physical science, the ideas of entropy, solutions, and concentrations can be overwhelming. Diffusion is easy to explain with a perfume bottle or food coloring. …