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A and B genes are linked. What shall be genotype of progeny in a cross between AB/ab and ab/ab : -
A
AAbb and aabb
B
AaBb and aabb
C
AABB and aabb
D
None
Detailed Solution
With complete linkage, the heterozygote AB/ab forms only parental gametes: AB and ab.
The homozygous recessive parent ab/ab forms only ab gametes.
Progeny: AB $\times$ ab = AB/ab (AaBb) and ab $\times$ ab = ab/ab (aabb), in a 1 : 1 ratio.
(If crossing over occurred, a few recombinants Aabb and aaBb would also appear.)
So the progeny genotypes are AaBb and aabb.
The homozygous recessive parent ab/ab forms only ab gametes.
Progeny: AB $\times$ ab = AB/ab (AaBb) and ab $\times$ ab = ab/ab (aabb), in a 1 : 1 ratio.
(If crossing over occurred, a few recombinants Aabb and aaBb would also appear.)
So the progeny genotypes are AaBb and aabb.