Name____________________________________ Date________________ Hour________________

GENETICS COMPUTER SIMULATIONS – TESTING MENDEL

GENETICS CD - 4

Directions: Obtain a CD entitled "Biology Explorer 3.04 Genetics" and a coin from your instructor. Go quietly to the Media Center computer lab. Insert the CD and then complete the following activity. Return the CD to your instructor when finished.

PURPOSE: To investigate the process Mendel used to discover the basis of heredity.

PROCEDURE:

    1. Go to the START MENU.
    2. Place your cursor on PROGRAMS.
    3. Move your cursor to "LOGAL Biology Teacher."
    4. Click on GENETICS MAIN MENU.
    5. Click on "EXPLORATIONS."
    6. Click on "TESTING MENDEL."
    7. <<At this point, the arrows to move around through the program are at the very bottom of the screen. We may have to grab and drag the Start menu tool bar downward until we can’t see it any longer in order to uncover the arrows we need.>>
    8. Follow the directions on each page to complete the exercise. Blue "hyperlinked" words in the directions text can be clicked on to perform certain functions.

QUESTIONS AND DATA TABLES:

  1. What do you think will be the ratio of straight-eared to floppy-eared offspring in the F2 generation? Make a prediction_____________
  2. Data table one:
    3.

    DOMINANT TRAIT VARIATION

    RECESSIVE TRAIT VARIATION

    TOTAL

    100 OFFSPRING

  3. Data table two:
    4.

    PERCENTAGE

    RATIO

    DOMINANT TRAIT IN F2

    RECESSIVE TRAIT IN F2

  4. What is the average ratio?_____________________
  5. What is the observed phenotypic ratio (straight-eared to floppy-eared)______________________
  6. How might you explain these results? Think about Mendel’s idea that parents pass on discrete hereditary elements to their offspring.

    7.  

     

     

     

     

     

     

     

     

  7. Punnett square:
    8.

    A

    ½

    a

    ½

    A

    ½

    a

    ½

  8. Calculate the expected genotypic ratios:

    9.  

     

  9. Based on thes information, now calculate the expected phenotypic ratios for stright ears and for floppy ears:

    10.  

     

  10. How does the expected phenotypic ratio compare with the observed phenotypic ratio that you calculated previously?

    11.  

     

  11. Let’s say you wanted to distinguish between an Aa and an AA individual. Could you do this by looking only at their phenotypes?

    12.  

     

     

     

     

  12. Punnett square:

    13. Cross AA x AA

    Expected phenotype of this cross____________________________________

  13. Punnett square

    14. Cross Aa x AA

    Expected phenotype of this cross____________________________________

  14. Would crossing with an AA individual help make the distinction?

    15.  

  15. Design a cross that would distinguish between the AA and the Aa genotype. This is called a test cross. (make your own Punnett squares…)

    16.  

     

     

     

     

  16. How many individuals of genotype AA and Aa did you identify among the 10 F2 individuals examined?_______________________
  17. If Mendel’s hypothesis was corret, based on your F1 Punnett square, what ratio of AA to Aa individuals would you expect in F2?

    18.  

  18. <<At this point, the program suggests to pool your data with your classmates. Post the results of your 10 F2 tests.>>

    19. Now that your sample size of F2 tested individuals is larger, do your results confirm Mendel’s hypothesis?_______________________

  19. Does the ratio of AA to Aa individuals you find confirn your and your classmates’ results?_______________________
  20. How does a test cross verify Mendel’s hypothesis?