Download Eye Colour

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Title: An investigation into the rate of brown hair and brown eye colour compared with the rate
of brown hair and non brown eye colour in high school students on Prince Edward Island
Background: Traditionally human eye colour is thought to be under the control of one specific
gene. That is the basis of the one gene equals one protein hypothesis. But we now know that
this is not always the case. Gone are the notions of Mendel’s simple dominance and recessive
characteristics. We now understand that genes can effect the expression of one another and
hard and fast rules do not necessarily apply. Indeed it is possible for people who possess the
recessive form of blue eyes to produce a child that has the dominant brown eye colour. What
other characteristics then have an effect on eye colour? Does hair colour have any effect on how
other pigment genes get expressed? Over the past century the rate of blue eyed Americans has
been declining (Belkin, 2006). Can the relatively recent increase of immigrants with more
pigmented characteristics influence the rate of blue eyes in North America in general? Is a
person more likely to have brown/black hair and brown eyes compared to brown hair and blue
eyes?
Hypothesis: If a person has dark hair then they are more likely to have brown eyes.
Variables:
Independent Variable
Hair colour
Dependant Variable
Eye colour
Controlled Variables
Age/Geographical location/ ?????
Procedure: This study took place at Colonel Gray High school on Prince Edward Island,
Canada on _________________. A group of _______ researchers working in teams of
___designed a basic hair colour and eye colour identification scheme. Dark hair is determined
to be any natural colour that can be characterized as dark or light brown. Hair colours such as
sandy blond, red, strawberry blond, blond and other light colours were not used. Shade of eye
colour was not distinguished outside of the brown eye colour or blue eye colour. Teams were
then assigned a classroom based on the agreement of the subject teacher to participate. A total
of 8 classes participated. Each class was then read a short statement of purpose explaining the
investigation and each student was given the choice to opt out of the project. A sample of the
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instructions is included as Appendix A. The number of people with dark hair and dark eyes
and the number of people with dark hair and blue eyes was recorded in each class.
Work Cited: Belkin, D. (2006, October 18). Blue eyes are increasingly rare in America The New
York Times, Retrieved from http://www.nytimes.com/2006/10/18/world/americas/18ihtweb.1018eyes.3199975.html
Appendix A - Class Statement
Good afternoon everyone. We are members of the Mr. MacCormack’s IB biology class
and we are studying gene frequency in populations. We would like to gather information about
your hair colour and eye colour in order to analyze any correlation between these variables. If
you would like to participate in this study simply allow us to record these variables. If you do
not, then simply shake your head when the researcher comes to your desk. Participation is
totally voluntary. If you have dyed hair please inform the data collector of you natural hair
colour
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