Question

A and B genes are linkedWhat shall be genoty of progeny in a cross between AB/ab and ab/ab? (1)AAbb and aabb 2)AaBb and aabb (3)AABB and aabb (4)aaBBx Aabb

Answer 1

Answer:

BIOLOGY

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 of the above

December 20, 2019Vikram Musale

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ANSWER

Since A and B genes are linked, the parental genotypes "AB/ab" and "ab/ab" will produce only non-cross over gametes. Recombinant gametes are not produced here; the genotype AAbb is product of fusion of recombinant gametes (Ab x Ab) which makes option A wrong. Since the second parent does not have "AB" gamete, AABB genotype cant be obtained from a cross between AB/ab and ab/ab. Thus, option C is wrong.

Parent generation  "AB/ab"   x   "ab/ab"

Gametes :

AB/ab  -->

ab/ab

  ABababAaBbaabbabAaBb      aabbOffspring genotypic ratio = 1 AaBb: 1 aabb. Hence, option B is correct.