Question

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

• A. 40%
• B. 70%
• C. 20%
• D. 15%

Answer 1

The correct option is D 15%

There is just 30% crossing over between genes A and B on same chromosome which means the probability is 30/100 or 0.3. If the plant has genotype AaBb in cis arrangement, then it will have four types of gamete as AB, Ab, aB and ab.
here, aB will be considered as recombinant gamete of the plant having genotype AaBb in cis arrangement and hence, the probability of occurrence of aB is just the half. , meaning, 50% or the probability as 0.5. Hence, the percentage of gamete aB formed is 0.5 x 0.3 = 1.5 or 15%.
Hence, the correct answer is '15%'.