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Select the correct statement from the ones given below with respect to dihybrid cross.
A
Tightly linked genes on the same chromosome show very few recombinations
B
Tightly linked genes on the same chromosome show higher recombinations
C
Genes far apart on the same chromosome show very few recombinations
D
Genes loosely linked on the same chromosome show similar recombinations as the tightly linked ones
Detailed Solution
Morgan's dihybrid crosses in $Drosophila$ showed that genes on the same chromosome tend to be inherited together (linkage).
The closer two genes lie on a chromosome, the less likely a cross-over is to occur between them, so tightly linked genes show very few recombinants.
Example: the genes for white eye and yellow body were very tightly linked and showed only 1.3% recombination, whereas white eye and miniature wing, which are farther apart, showed 37.2% recombination.
Thus genes far apart (loosely linked) show higher recombination, not lower or the same.
Hence the correct statement is that tightly linked genes on the same chromosome show very few recombinations.
The closer two genes lie on a chromosome, the less likely a cross-over is to occur between them, so tightly linked genes show very few recombinants.
Example: the genes for white eye and yellow body were very tightly linked and showed only 1.3% recombination, whereas white eye and miniature wing, which are farther apart, showed 37.2% recombination.
Thus genes far apart (loosely linked) show higher recombination, not lower or the same.
Hence the correct statement is that tightly linked genes on the same chromosome show very few recombinations.