Week 10, Chapter 7 -- Digging Deeper Course home | Weekly schedule | Announcements | Instructor Info | Desire2Learn | MasteringBiology® | Honor Code | FAQs | HELP!

Introduction:

One of the thorniest questions in the science of inheritance is "Is this trait a product of genes, environment, or both?" This week's reading has tried to explain that most interesting human traits are a product of both genes and the environment. Teasing apart their relative contributions is very difficult, and sometimes impossible. Your job this week will be to try to devise an experiment that will help you learn about the methods -- and limitations -- for measuring the heritability of the trait of your choice.

Instructions:

Choose a continuously variable (quantitative) trait in humans or any other organism (see your text for definitions.) With the exception of traits with simple Mendelian inheritance, most features fit this description. (You can tell if it is Mendelian if there are only two or three possible phenotypes). Let your mind be free. Go beyond the obvious features like human skin color, IQ, height, and weight. Think about tail length in cats, the weight of tomatoes produced per plant, the number of mushrooms produced per individual in a particular type of fungus. Think about anything you can observe about any organism – you can choose almost any trait you want, as long as its inheritance is quantitative, not qualitative.

For this assignment, your overall job is to design an experiment that would help you determine the heritability of the trait you chose. For full credit, your assignment must include the following components:

• A description of the trait you chose, why you chose it, and three environmental (not genetic) factors that might influence expression of the trait.
• The approach you have chosen for your experiment. Your textbook lists three basic ways to do this: artificial selection, correlation, and twin studies. Choose one as the basis for your experiment, and explain why you chose it (as opposed to the other two methods).
• Describe your basic experimental design (including sample size and duration) and how you will measure the expression of the trait you chose.
• Predict the outcome of your experiment if heritability is high and if it is low.
• What are the limitations of your proposed study?

You must include correctly cited links to all references (if any) you used in creating your installment.

The word count should be 450 words or more; you can view a sample assignment here.

Part 2:

Use D2L's spell checker (or the one on your word processor software, which will give you a word count as well). Proofread it yourself too, because spell checkers don't catch everything. When you are satisfied, post your completed assignment in the Digging Deeper forum for this week at the D2L discussion board.

Part 3:

Respond to at least two other students’ explanations. (If you are the first or second person to post, you will have to check back later to complete this part of the assignment). Your response should address whether the experiment would test for heritability and whether the limitations are adequately described.

• Just as you spell checked and proofread your original post, you should do the same for your responses.
• Please respond to posts with 0 responses first; once every post has at least one response, you are free to choose any post to respond to.
• When you respond, please use the name of the student you are responding to. That is, say "Hi Trudy" or "Hi Paul" so that you can get used to the names of the people in class. (You can find a list of "real" names and D2L names at the D2L discussion board).
• In your response, be sure you mention something specific that the writer did well. Also, specifically address anything you find that seems incorrect to you (phrased in a constructive way -- use the same language you would want someone else to use in telling you something you did wrong). I don't mean spelling errors and typographical errors. I mean more substantive comments. You may wish to argue with (or critique) what the student wrote, request supporting evidence, evaluate the student's argument, add new information, make a factual correction, or explain why you agree. Check out this page for more on the topic of good and bad responses.

After you have posted your assignment AND responded to two other students, go to Desire2Learn and complete the Gradebook Declaration for this week's Digging Deeper assignment. (Your Gradebook Declaration is subject to the Honor Code.)

Contemporary Issues in Biology -- BIOL 1003 Mariëlle H. Hoefnagels, Ph.D. © 2004-2015. biology1003 at OU dot edu (at = @, dot =.) Last Updated August 5, 2014 11:02 PM