Objective To visually show the results of dominant traits and recessive traits.
Procedure This exercise works best with an overhead projector.
Materials Pieces of brown and colorless acetate samples. (4)
Collecting Data
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A. Make a large Punnett Square and use the acetate pieces to represent a dominant trait. Record.
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B. Show result of a cross of two each with one recessive gene (colorless). Record.
Conclusion
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1. Explain the results.
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2. Research some diseases of dominance inheritance and diseases caused by recessive inheritance.
Problem How often do certain human traits manifest themselves?
Procedure Two traits to be studied are the ability to roll one’s tongue and how the earlobe is attached. The ability to roll one’s tongue is dominant over the inability and will be assigned the capital R. The inability will be designated by the small r. The small r is recessive.
Earlobes are either free or attached to the jaw. The free earlobes are dominant and represented by the capital letter E. The attached earlobes are recessive and represented by the small e.
The data will be shown for earlobe attachment in three ways; (a) by a human pedigree chart, (b) by a Punnett square, (c) and by a genotype-phenotype chart.
Free
(figure available in print form)
Attached
(figure available in print form)
Rolled tongue
(figure available in print form)
(figure available in print form)
Conclusion
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1. Explain the results of your experiment.
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2. Try to get so results from family or other friends.