Science Buddies: "Ask an Expert"

hi, i'm a 7th grader and I want to do the dominant traits project for my science fair. i figured i could use my family as the dependent variable and a friends or cousins family as independent variable, but i'm having trouble figuring out my control. can you help me please? i plan to use the eye color, ear lobe detached/attached and hair color as the traits. thank you

Hello,

Your topic idea seems to be a pedigree analysis project. It might be difficult to define a dependent, independent, or control variable in this case. You may want to instead create a pedigree chart of your family and test a trait for each family member. You can determine the "dominant traits" from the pedigree.

This project "Pedigree Analysis" (https://www.sciencebuddies.org/science- ... t&from=TSW) sounds like the project you are trying to set up. Check to see if this is what you're looking for. Hope this helps.

Hi,
Am trying to determine what your experiment is. You aren't really manipulating a variable, you are just reporting on what traits appear to have been passed on within a family. I don't think this can be done as an experimental design. You might want to review what makes up an experiment. To the best of my knowledge, at your grade level, judges are looking for an experiment with an "if - then" statement. "If I do this, then this will happen".
Carrol

Hi there,

Your project does sound like a pedigree analysis. Because you are looking at things that have already happened, you cannot really define a dependent and independent variable for that. (The independent variable is the one you, the scientist, changes, and the dependent variable is what changes in respons to the independent variable. In the case of a pedigree, you are not manipulating anything; you are just observing.)

If you are interested in conducting an experiment looking at dominant traits, you could consider working with an organism that's easy to observe. Geneticists have often used fruit flies (Drosophila melanogaster to look at the inheritance patterns of different traits. Some plants work well for this, too; but they take much longer to observe.

Let us know what kind of project works for you, and we can give you more guidance from there!

Heather