Question

Assertion (A): In dihybrid crosses involving sex-linked genes in \(\textit{Drosophila}\), generation of non-parental gene combinations are observed 
Reason (R): Two genes present on different chromosomes show linkage and recombination in \(\textit{Drosophila.}\)

• A. \(( \text{Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).} )\)
• B. \(( \text{Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).} )\)
• C. \(( \text{Assertion (A) is true, but Reason (R) is false.} )\)
• D. \(( \text{Assertion (A) is false, but Reason (R) is true.} )\)

Answer 1

The Correct Option is C

Assertion is true. In dihybrid crosses involving sex-linked genes in \textit{Drosophila}, non-parental gene combinations (recombinant types) are indeed observed in the offspring. This is due to crossing over (recombination) that occurs during meiosis in the heterozygous female. Reason (R) is false. Two genes present on different chromosomes assort independently and do not show linkage. Linkage refers to the physical association of genes on the same chromosome. Genes on different chromosomes undergo independent assortment, leading to new combinations of traits. Recombination also occurs between genes located on the same chromosome due to crossing over. Therefore, the statement that genes on different chromosomes show linkage is incorrect.