1.A variety of pea plant called Blue Persian produces a tall plant with blue see
ID: 51594 • Letter: 1
Question
1.A variety of pea plant called Blue Persian produces a tall plant with blue seeds. A second variety of pea plant called Spanish Dwarf produces a short plant with white seeds. The two varieties are crossed and the resulting seeds are collected. All of the seeds are white and when planted, they produce tall plants. These tall F1 plants are allowed to self-fertilize. The results for seed color and plant stature in the F2 generation are as follows:
F2 Plant Phenotype Number
Blue seed, tall plant 97
White seed, tall plant 270
Blue seed, short plant 33
White seed, short plant 100
a) Which phenotypes are dominant and which are recessive?
b) What is the expected distribution of phenotypes in the F2 generation?
c) State the hypothesis being tested in this experiment.
d) Examine the data in the table by the chi-square test and determine whether they conform to expectations of the hypothesis. Be sure to state your p value.
2.
Organisms with the genotypes AABbCcDd and AaBbCcDd are crossed. Loci independently sort. What are the expected proportions of the following progeny?
a) A_B_C_D_
b) AabbCcDd
c) a phenotype identical to either parent
d) A_B_ccdd
Explanation / Answer
The dominant phenotypes are white and tall. Recessive phenotypes are blue and short.
The expected distribution of phenotypes in the F2 generation is 9:3:3:1 for White tall : blue tall : white short : blue short
The hypothesis being tested is if the genotypes follow the Mendelian pattern of inheritance.
The following is the calculation of chi square for the given values:
Exp (E)
Obs (O)
(O-E)
(O-E)2
281.25
270
11.25
126.6
93.75
97
-3.25
10.6
93.75
100
-6.25
39.1
31.25
33
-1.75
3.06
500
179.36
P value = 0.78
Exp (E)
Obs (O)
(O-E)
(O-E)2
281.25
270
11.25
126.6
93.75
97
-3.25
10.6
93.75
100
-6.25
39.1
31.25
33
-1.75
3.06
500
179.36
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