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18 min video- Ten thousand years ago, corn didn't exist anywhere in the world, and until recently scientists argued vehemently about its origins. Today the crop is consumed voraciously by us, by our livestock, and as a major part of processed foods. So where did it come from? Popped Secret: The Mysterious Origin of Corn tells the story of the genetic changes involved in the transformation of a wild grass called teosinte into corn.  Evidence from genetics supports archeological findings pinpointing corn's origins to a very particular time and place in Mexico

To what extent should corn be used for the production of ethanol? Are we better off producing corn for food or producing corn for fuel? This case study uses a technique called "intimate debate" (also known as "constructive controversy") in order to examine this issue. Each student participates in a set of mini-debates for which there is no audience. Students are paired with a teammate; these teams then take turns arguing each side of the issue while seated across from their opponents who do the same. The session concludes with opposing teams reaching consensus. Detailed instructions are included in the case handout to prepare students for the experience before debate day. This case was used successfully in a sophomore/junior level, general education, environmental biology course. It would fit appropriately into any college course that discusses environmental issues related to farming practices, land use, alternative fuels, renewable energy, or sustainability.

It took about 9,000 years and alterations in six genetic pathways to transform the inedible grass teosinte (left) into the corn we eat today (right). (Center: a first generation hybrid between teosinte and corn)

Corn was originally bred from the teosinte plant by native Mexican farmers. The morphologies of modern-day corn and teosinte plants are compared to illustrate how artificial selection can bring about dramatic changes in plants.

GMOs are organisms that have had their DNA modified through genetic engineering. This is often done by taking a gene from one organism and putting it into another one to alter it in a desirable way. For example, when genetic engineers want to create a corn crop that is resistant to pests, they seek out the trait in Bacillus thuringiensis (Bt) soil bacteria that naturally acts as a pesticide. From there, engineers isolate the gene responsible for that trait and directly insert it into the corn's DNA. This corn is then bred with other corn until it's ready to be produced for consumption.

Why is the North American population of monarch butterflies declining? In 1999, a study published in the journal Nature suggested that a variety of genetically modified corn was killing these iconic butterflies. While it was later shown that the conditions in this study did not mirror those in the field, the results garnered a lot of media attention and many people today still believe that monarchs are being killed by GMOs. This case familiarizes students with the plight of the monarchs, encourages them to think about how to test the hypothesis that a toxin is responsible for their decline, and takes a critical look at several studies that investigated the role of Bt corn in the life cycle of monarchs. This interrupted case takes 60-90 min to complete, requires little to no science background, and can be used to explore the ecology and wildlife management of monarchs; risk assessment, toxicity, and exposure; experimental design, the scientific method, hypothesis, and critical thinking; or the relationship between science, the media and the public.

With increasing U.S. government support for biofuel production in the late 2000s came increased pressure to convert more land to cornfields for ethanol. To make way for more corn, millions of acres of prairie grassland were plowed under, destroying an extremely diverse wildlife habitat that also served as a large carbon reservoir. This case study focuses on the reasons for and consequences of large carbon losses when prairie grasslands are converted to agricultural lands. Many students are challenged when faced with linking together energy flows, decomposition, and nutrient cycles.  This case gives students the opportunity to consider different pools in the carbon cycle and the fluxes between them in order to model (on paper) an integrated picture of why carbon is lost when prairie grasslands are plowed and planted to cornfields.  Students also consider ways that carbon loss from land conversion due to ethanol production might be avoided via government incentive programs or mitigated via changes to farming practices. This case study was developed for an introductory ecology, environmental science, soil science, or agriculture course.

The study is the first to examine all of the gene networks affected by fructose that result in changes to brain function and metabolism-more than 20,000 genes in total. Although the study was conducted using rats, the researchers report that the majority of the sequenced genes are comparable to those in humans, including more than 200 genes in the hippocampus, a brain area crucial to memory, and 700 in the hypothalamus, the seat of the brain's metabolic control center.