. In an experiment, AaBb (F1) was test crossed with aabb In the progeny, genotypes Aabb, aaBb were more frequent than AaBb and AABB


In an experiment, AaBb (F1) was test crossed with aabb In the progeny, genotypes Aabb, aaBb were more frequent than AaBb and AABB. The genotypes of the parent of F1 should be

A.         AABB and aabb.                                

B.         AAbb and aaBB.

C.         AAbb and AABB.                               

D.         AABB and aaBB.

Best Answer

B.    This is due to ‘trans’ (AAbb X aaBB) arrangement of genes, which produces more recombinants. Coupling (Cis arrangement) of genes (AABB X aabb) brings more of parental types.

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