Interestingly enough, the Spruce, a very common Christmas tree species, has seven times more DNA than a human. How is that, you say?  They are but simple trees, and we are complex animals with skills and intellect beyond compare! Well, you may not say that, but my students do! I shared that little gem with my class today, and they were shocked.

It turns out that all conifers like the Spruce, have 12 chromosomes (humans have 46), but they are really big. Scientists aren’t sure why this is so, but some speculate that this large amount of DNA may be how they have been such a successful plant, surviving for millions of years. There are several plant species that have way more DNA than we do, which brings to light the questions: Does more DNA make an organism more complex? Could a plant be more complex than a human? I suppose that depends on who you ask.

What I do know is that I love my Christmas tree, and all 12 of its giant chromosomes!

To read more about the Spruce geneome project in Sweden, go to: http://www.innovations-report.com/html/reports/agricultural_sciences/christmas_tree_times_dna_time_map_145376.html

Demonstrations with this wheel have led to some very interesting student responses and questions.  I have been accosted in the museum by students who believe that the wheel has actually predicted what gender their children will be, and even how many they will have!  This has led me to beat them to the punch during my demonstration, by explaining that the wheel is not a predictor of the future!

I have also been asked by concerned 10-year-olds, how much DNA their parents could possibly have left over after having 4 children? This one is a favorite of mine. When you really think about it, that thought makes perfect sense. Unless you’ve learned about meiosis and sex cells, how would you know that there are special cells, each containing extra copies of the genetic information to be passed on to children? In avoidance of these “uncomfortable” topics, some children are somewhat mislead when they begin learning about inheritance.

When I work with 5^th graders and discussions of 46 chromosomes per cell come up, I always add that some cells have no DNA (mature red blood cells) and some cells have only 23 chromosomes.  Inevitably, someone will ask why, and if they don’t I do! There are special cells that are used for reproduction, and when two of these cells unite, from a mother and a father, a full set of chromosomes is created. Covering this basic concept without the burden of meiosis, is perfectly suitable for 10-year-olds, and eliminates confusion.o