Self Assessment Question # 2
for Lesson 10

by Dr Jamie Love © 2002 - 2010
Genetics Course

Here are the results of a dihybrid cross involving roses. There is no need to tell you their history other than to say they are the result of a proper dihybrid cross. The F2s produced had these phenotypes and in these numbers.
Red and tall = 30
White and tall = 65
Red and short = 83
White and short = 206
Use the chi-square to determine if these results are what you would expect for the dihybrid cross.
Note and warning! This will take you more time and effort than the other chi-square, in the first SAQ of this section, so take it one step at a time and be sure you remind yourself that there are now four categories. You might want to set this up as a neatly organized table to follow because it gets pretty complicated!
2 = [(O - E)2/E]

Degrees of Freedom 5 % Significance Levels
1
3.84
2
5.99
3
7.81
4
9.49

Don't give up. If you get confused take a break, go back to read the section about chi-square again, or review the workshop.

Go to the ANSWER