Homework SourseA peaproducing farmer carried out a genetic cross using the
A pea-producing farmer carried out a genetic cross using the following true-breeding plants: a round, yellow pea and a wrinkled, green pea. The resulting F1 generation was allowed to self-cross to produce F2 generation. The following data were obtained:
F1 generation: all offspring were round and yellow
F2 generation: 205 round and yellow, 65 round and green, 95 wrinkled and yellow, 35 wrinkled and green
a) What is one hypothesis you can generate with respect to Mendel’s law of dominance and law of independent assortment?
b) Test the goodness of fit between the data and your hypothesis using a chi square test.
c) Explain what your calculated chi square results mean – do you accept your hypothesis based on your calculated chi square results and why?
Solution
a) What is one hypothesis you can generate with respect to Mendel’s law of dominance and law of independent assortment?
The above two characters are showing complete dominance and independent assortment.
b) Test the goodness of fit between the data and your hypothesis using a chi square test.
Null hypothesis: The observed values are not deviating from the 9:3:3:1 ratio.
Category
round and yellow
round and green
wrinkled and yellow
wrinkled and green
Total
Observed values
205
65
95
35
400
Exptected Ratio
9
3
3
1
16
Exprected Values
225
75
75
25
Deviation
-20
-10
20
10
D^2
400
100
400
100
D^2/E
1.777778
1.333333
5.333333
4
12.44444
X^2
12.44444
Degrees of freedom
4-1
3
Inference: The calculated chisquare values 12.4 is grater than the table values at 0.05 probability and 3 DF i.e. 7.82. Hence null hypothesis rejected.
c) Explain what your calculated chi square results mean – do you accept your hypothesis based on your calculated chi square results and why?
The calculated chisquare values 12.4 is grater than the table values at 0.05 probability and 3 DF i.e. 7.82. Hence null hypothesis rejected.
| Category | round and yellow | round and green | wrinkled and yellow | wrinkled and green | Total |
| Observed values | 205 | 65 | 95 | 35 | 400 |
| Exptected Ratio | 9 | 3 | 3 | 1 | 16 |
| Exprected Values | 225 | 75 | 75 | 25 | |
| Deviation | -20 | -10 | 20 | 10 | |
| D^2 | 400 | 100 | 400 | 100 | |
| D^2/E | 1.777778 | 1.333333 | 5.333333 | 4 | 12.44444 |
| X^2 | 12.44444 | ||||
| Degrees of freedom | 4-1 | 3 |
