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Question: Answered & Verified by Expert
The linkage map of $\mathrm{X}$-chromosome of fruitfly has 66 units, with yellow body gene $(y)$ at one end and bobbed hair $(B)$ gene at the other end. The recombination frequency between these two genes $(y$ and $b$ ) should be:
BiologyPrinciples of Inheritance and VariationNEETNEET 2003
Options:
  • A $66 \%$
  • B $>50 \%$
  • C $\leq 50 \%$
  • D $100 \%$
Solution:
2254 Upvotes Verified Answer
The correct answer is: $\leq 50 \%$
The yellow body gene (y) and bobbed hair (B) gene are present 66 map unit apart which means that there is $ < 50 \%$ chances of recombination between them (recombination frequency).
Related Theory
One map unit is equal to $1 \%$ recombination frequency. This linear relationship holds true for lower values only; as the recombination frequency increases beyond $50 \%$, the linear relationship does not hold true owing to double and multiple cross overs and recombination frequency is always less than map distance and never exceeds than $50 \%$.

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