Mendelian Genetics with Fastplants, Corn on the Cob, and Sickle Cell Anemia

We've been increasing our repertoire of labs that students can do as we're talking about Mendelian and non-Mendelian genetics.

One of the labs that we've done for two years now is with Fastplants. This is another lab I use from Lee Ferguson and is on her website here under the Mendelian genetics link. Since I have small classes, I only buy one set of F2 seeds and all of the lab groups germinate the same type of seeds. Then we pool all of our data to analyze it. Last year, we used the F2 crosses of purple vs. green stems, and green vs. yellow leaves. We had a terrible time distinguishing the color of leaves since purple stems make the yellow leaves look greener, and green stems make the green leaves look lighter. Although we had great germination rates, our ratios were not even close to the expected. In our class discussion of our results, we decided it was due to the difficulty in distinguishing leaf color.

This year, I decided to go with green vs. purple stem and dwarf vs. normal height. My students were pretty excited about how well the seeds germinated and how as they sorted them by phenotype how close the numbers were to the expected values. They were pretty stoked about how small their chi-squared value was for our class data. I love it when they get excited about this kind of stuff! I think part of it is that they often complete labs with fairly high percent errors, and it's actually satisfying for results to go so well. They all agreed that this was a great variety of seeds to analyze. I'll be ordering this variety again next year.

Another lab that allows us to look at the ratio of phenotypes in a dihybrid cross involves looking at ears of corn. I went to an APSI this summer and one of the labs that I won was a class set of ears of corn from a dihybrid cross involving yellow vs. purple and smooth vs. wrinkled.

The lab we use to analyze the ears is from Biologycorner.com and you can find it here.

Another activity that I've added to our genetics unit is from HHMI Biointeractive. We do the activity titled Mendelian Genetics, Probability, Pedigree, and Chi-Square Statistics and the teacher and student materials can be found here. We watch the short film first, that is also found on that page, and move onto the questions. I like the introduction to sickle cell anemia since we'll revisit it when we get to the natural selection unit.