3 A-:1 aa 2. The following are dihybrid testcross data. Do these data approximat
ID: 190634 • Letter: 3
Question
3 A-:1 aa 2. The following are dihybrid testcross data. Do these data approximate the ratio one for independent assortment? Complete the table, calculate the , and answer the questions related to your calculations. Phenotype o O-E 4-bh 61 aaB aabb Totals 551 degrees of freedom a. In interpreting this ' value, you have b. In this case, do you accept/reject the hypothesis that these data approximate the dihybrid test cross ratio with independent assortment? c. What is the probability that the deviations are due to chance alone? d. Complete the following table for the data given in this problem. Note that the data in this prob- lem are dihybrid testcross data. Now, determine whether cach gene pair is behaving individu- ally as you would expect in a monohybrid testcross. Each trait considered individually should be expected to approximate a 1:1 ratio as a consequence of Mendel's law of segregation. Accept or reject hypothesis Hypothesis value P valucExplanation / Answer
Null hypothesis: The observed values are not deviating from the mendilian dihybrid testcross ratio i.e. 1:1:1:1.
Test static – Chisquare test:
Category
A_B_
A_bb
aaB_
aabb
Total
Observed values
102
61
71
97
331
Exptected Ratio
1
1
1
1
4
Exprected Values
82.75
82.75
82.75
82.75
Deviation
19.25
-21.75
-11.75
14.25
D^2
370.5625
473.0625
138.0625
203.0625
D^2/E
4.478097
5.716767
1.668429
2.453927
14.31722
X^2
14.31722
Degrees of freedom
4
-
1
3
Inference: The calculate chisquare value i.e. 14.31 is greater than the table value i.e. 7.82 at 3 DF and 0.05 probability. Hence the null hypothesis is rejected.
Category
A_B_
A_bb
aaB_
aabb
Total
Observed values
102
61
71
97
331
Exptected Ratio
1
1
1
1
4
Exprected Values
82.75
82.75
82.75
82.75
Deviation
19.25
-21.75
-11.75
14.25
D^2
370.5625
473.0625
138.0625
203.0625
D^2/E
4.478097
5.716767
1.668429
2.453927
14.31722
X^2
14.31722
Degrees of freedom
4
-
1
3
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