A variety of pure-breeding snapdragons produces a tall plant with green seeds (W
ID: 253802 • Letter: A
Question
A variety of pure-breeding snapdragons produces a tall plant with green seeds (WWSS). A second variety of pure-breeding snapdragons produce a short plant with white seeds (wwss). The two varieties are crossed, and the resulting seeds are collected. All of the seeds are green and when planted, they produce all tall plants (WwSs). These tall F1 plants are allowed to self-fertilize. The results for seeds and plant height in the F2 generations are as follows. What is the ?2
value, and the degrees of freedom for this experiment?
F2 Plant phenotype
Observed #
Green seed, tall
588
White seed, tall
155
Green seed, short
162
White seed, short
95
Total
1000
?2 = 27.1, df = 1
?2 = 27.1, df = 3
?2 = 3.1, df = 3
?2 = 3.1, df = 4
?2 = 3.1, df = 1
?2 = 27.1, df = 4
F2 Plant phenotype
Observed #
Green seed, tall
588
White seed, tall
155
Green seed, short
162
White seed, short
95
Total
1000
Explanation / Answer
The answer is ?2 = 27.1, df = 3
For explanation find the below calculation...
Null hypothesis: The observed values are not deviating from the F2 ratio of the mendilian dihybrid cross ratio i.e. 9:3:3:1
Test static:
Category
Green seed, tall
White seed, tall
Green seed, short
White seed, short
Total
Observed values (O)
588
155
162
95
1000
Exptected Ratio (ER)
9
3
3
1
16
Exprected Values (E)
562.5
187.5
187.5
62.5
Deviation (O-E)
25.5
-32.5
-25.5
32.5
D^2
650.25
1056.25
650.25
1056.25
D^2/E
1.156
5.633333
3.468
16.9
27.15733
X^2
27.15733
Degrees of freedom
4
-
1
3
Inference: The calculated chisquare value i.e. 27.15 is greater than the table value i.e. 7.82 at 3 DF and 0.05 probability, hence the null hypothesis is rejected.
Category
Green seed, tall
White seed, tall
Green seed, short
White seed, short
Total
Observed values (O)
588
155
162
95
1000
Exptected Ratio (ER)
9
3
3
1
16
Exprected Values (E)
562.5
187.5
187.5
62.5
Deviation (O-E)
25.5
-32.5
-25.5
32.5
D^2
650.25
1056.25
650.25
1056.25
D^2/E
1.156
5.633333
3.468
16.9
27.15733
X^2
27.15733
Degrees of freedom
4
-
1
3
Related Questions
drjack9650@gmail.com
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.