Solve this:
Two genes A and B present on same chromosome show 30% recombination frequency, then what will be the percentage of gamete (aB) for the plant having genotype AaBb in cis arrangement :

(1) 40%                                 (2)70%
(3) 20%                                 (4) 15%

Dear Student,

Option 4 is correct.
There is 30% crossing over of A and B present on the same chromosome that means the probability of occurring of crossing over is 30/100 that is 0.3
Now if the cell has genotype AB/ab in cis arrangement then it has four types of gametes i.e AB, Ab, aB, ab. In which two gametes are of recombinant type and other is of parental type.
Considering aB as recombinant gamete of the plant having genotype Aa Bb is cis arrangement, therefore the probability of occurrence of aB is 1/2 i.e 50% or 0.5 Hence, the percent of gamete aB formed is 0.3 X 0.5 that is 1.5 So, the probability is 1.5 that is 15%.


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