All of the groups did a nice job. Well done, 7th graders!

I’ve also added a PDF to the blog post of the moth pictures I used. Print the two sides back to back. Then count out enough for your students–about 1/4 of them dark moths. For each three light moths–write bB, Bb, and BB for phenotypes. On the dark moths–write bb. The rest of the phenotype sides will stay blank. Students fill out the Punnet squares and then take four more moths based on the phenotypes on their Punnet squares, writing the phenotype on the back of the moths.

I hope that helps. I’d love to hear about your class’s experience!

Mrs. Krebs

Genetics is an interesting study and was something I studied while at university. I know of the story of the peppered moth. It is one of the classic examples of how change in the environment can influence survival of individuals.

As you found, with growing industrialisation, darker moths were harder to see by predators and therefore were less likely to be taken. With coal being the major source of power, you can imagine the dark smoke from fire settling its soot and ash on anything in the open.

When seeing traits as you studied, it reminded me of something that had interested me in my studies, the recessive gene. When this type of gene was present, it only showed itself if it was inherited from both parents, the ‘bb’ genotype in your Punnett squares.

An example of a recessive gene can be found in lions of the Timbavati region of South Africa. Those animals that have recessive genes from both parents ‘bb’, have a white appearance. If they are BB or Bb, to use your Punnett square example, they appear normal in colour. The lions aren’t albino, although albinism is also an example of a recessive gene.

If you want to see what the white lions look like, below is a link to Mogo Zoo in Australia about a two hour drive from where I live…

http://www.mogozoo.com.au/animals/animals_wlion.html

They are beautiful animals.

@RossMannell
Teacher, NSW, Australia

Mrs. Krebs