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Life Science

  • Bacterial Hydrolysis of Starch In this lab, students culture two bacteria on potato dextrose agar, which contains starch. When grown on potato dextrose agar, bacteria that can secrete amylase—an enzyme that hydrolyzes starch—create a zone around their colonies in which starch is absent. When the agar is flooded with iodine solution, most of the plate stains dark blue–black, but clear areas are left around colonies that secrete amylase. View »
  • Bacterial Growth on MacConkey Agar In this lab students culture three bacteria on nutrient agar and MacConkey agar and record the results. View »
  • The Science Behind Lactose Intolerance Rumbly tummy after that milkshake? It could be lactose intolerance. In this brief overview, we’ll examine its causes, symptoms, and genetic underpinnings—plus point you toward some resources for further investigation. View »
  • Bacterial Hydrolysis of Lipids In this lab, students culture two species of bacteria on agar medium that contains an emulsion of plant oils and the dye, sprit blue, which forms a complex with the triglycerides of the oils and gives an opaque blue color to the agar. Colonies of bacteria that can secrete lipase, an enzyme that hydrolyzes triglycerides, develop a light area or “halo” in the surrounding medium, due to the diffusion of lipase into the medium and the resultant breakdown of the oil/spirit blue complex. View »
  • What Genomics Says about Being Human Part I Drastic reductions in the cost of determining the nucleotide sequences of chromosomes have led to an explosion in the field of genomics, enabling scientists to add remarkable depth to our understanding of what it means to be human. View »
  • Teaching About the Human Body Systems Are you ready to enhance your body systems curricula? Check out our free resources for teaching body systems. Pair them with models, dissection specimens and supplies, safety equipment, and more. View »
  • Termite Pheromones This investigation demonstrates how soldier termites sense pheromones. Students observe and document motions of termites under 2 different conditions: pencil circles and pen circles. View »
  • Isolating Bacteria from a Mixture How does a microbiologist isolate bacteria from a sample? In this lab students practice streaking a plate to isolate a single species of bacterium from a known mixture. View »
  • Bacterial Motility In this lab, students perform two exercises that investigate microbial motility. One is on a microscopic level, using the “hanging drop” slide preparation method to directly observe motile cells. The second exercise is on a macroscopic level and involves inoculating motility test media. View »
  • Bacteria: The Citrate Test In this lab students perform a test on two different bacteria to determine whether the organisms can use citric acid as their sole carbon source. The citrate test is often performed as part of the IMViC (Indole, Methyl Red, Voges-Proskauer, and Citrate) series of tests used to differentiate common species of enteric bacteria. View »
  • Examples to Use When Teaching About Selection and Evolution: Fox Domestication and Poison Resistance in Rodents To make abstract science concepts more concrete, teachers often use real-life examples. But even classic examples can lose their appeal. Refresh your lessons on evolution and selection with 2 less well known examples. View »
  • Introduction to Prokaryotes: Bacteria What are bacteria? In this introductory lab students make smears of bacteria on microscope slides from pure cultures, perform a simple stain, and observe their stained slides under a microscope View »
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