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Grade 7 Studies Genetics, Heredity
Posted 03/13/2018 01:23PM
Baldwin's 7th grade scientists recently wrapped up a unit on genetics and heredity by designing their own experiments and performing genetic crosses. Following in the footsteps of the father of modern genetics, Gregor Mendel, they used flowering plants as their experimental subjects. The experiment integrated information from vascular plant anatomy, pollination and advanced genetics concepts.

Using the simple idea that the phenotypes, or visible traits, of the offspring can inform scientists about the genotypes or genetic make-up of the parents, students selected their own back-crosses to answer an experimental question. Each question was of their own design using Wisconsin fast plants as a model organism. Wisconsin fast plants make the ideal test subject because they go from seed to seed in less than 40 days. This means that we can plant the seeds, cross pollinate the flowers in any combination, harvest and plant the new seeds and have the product of those genetic crosses within a matter of weeks.

Our Baldwin girls dove right in and made sure the plants were fed and watered, coming each day eager to see the changes in the plants' growth and development. They took careful notes, made observations and drew diagrams. The excitement was palpable when the first flowers began to appear in the brightest of yellows. It was a matter of now choosing the parent plants and the particular heritable trait they were interested in studying.

Using bees as pollinators, the girls learned about the importance of pollination and how fertilization through this method results in genetic diversity and variation important for survival and fitness in changing environments. They were able to experience firsthand the symbiosis of bees and flowers, and how the structure of the bees relates to the functional role of pollen collection. A single bee can carry about half her own body weight in pollen to take back to the hive, but flowers need just a little of that to land on their stigma to allow for fertilization. Similarly, a single Baldwin Bear can carry about half her body weight in textbooks, but just a little critical thinking, landing on connected ideas, can lead to a lifetime of learning.

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