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Question: Answered & Verified by Expert
Two linked genes a and b show 20 % recombination. The individuals of a dihybrid cross between + + / + + crossed with ab / ab shall show gametes
BiologyPrinciples of Inheritance and VariationNEET
Options:
  • A + + 80 : ab : 20
  • B + + 50 : ab : 50
  • C + + 40 : ab 40 : + a 10 : + b 10
  • D + + 30 : ab : 30 : + a 20 : + b : 20
Solution:
2849 Upvotes Verified Answer
The correct answer is: + + 40 : ab 40 : + a 10 : + b 10
Two linked genes a and b show 20 % recombination, thus linkage is 80%.  The given phenotype of parents is ++/++ and ab/ab.

The parental genotype will be ++ and ab, while the recombinant type will be +a and +b.

Since % of recombination i.e. cross over frequency is 20%, the recombinant phenotype will be 10% each.

+a: 10%
+b: 10%

Similarly, since linkage is 80%, parental types will be 80% or 40% each for ++ and ab respectively.

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