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Assertion : When yelow bodied, white eye...

Assertion : When yelow bodied, white eyed Drosophila females were hybridised with brown-bodied, red eyeed males , and `F_(1)` progeny was intercrossed, `F_(2)` ratio deviated from `9:3:3:1`
Reason : When two genes in a dihybrid are on same chromosome, the proportion of parental gene combinations are much higher than the non-parental type

A

If both the assertion and reason are true and reason is the correct explanation of assertion

B

If both assertion and reason are true but reason is not the correct explanation of assertion

C

If assertion is true but reason is false

D

If both assertion and reason are false

Text Solution

Verified by Experts

The correct Answer is:
A
In Drosophila, the genes for body and eye colour are located on X chromosome. When two genes in a dihybrid cross are situated on the same chromosome, the proportion of parental gene combination are higher than non-parental type. This occurs due to physical association or linkage of the two genes while non-parental gene combinations due to recombination between genes. Thus, linkage and recombination deviates the ratio form Mendelian ratio of a dihybrid cross `(9:3:3:1)`
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Morgan hybridised yellow-bodied, white-eyed females to brown-bodied red-eyed males and intercrossed their F_(1) progeny. He observed that (a) F_(2) ratio was deviated very significantly from the 9:3:3:1 ratio (b) Both genes did not segregate independently of each other (c) Recombinant types are not obtained in F_(2) generation (d) Both genes segregate independently of each other Select the correct set of statements :

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