In a testcross involving F 1 dihybrid flies, more parental-type offspring were produced than the…

In a testcross involving F1 dihybrid flies, more parental-type offspring were produced than the recombinant-type offspring. This indicates:
  1. The two genes are located on two different chromosomes
  2. Chromosomes failed to separate during meiosis
  3. The two genes are linked and present on the same chromosome
  4. Both of the characters are controlled by more than one gene

Solution

If a plant with genotype AaBb is crossed with that with aabb, then independent assortment would result in the production of 4 types of offsprings in equal proportion.
AaBb - gametes: AB Ab aB ab
Aabb - gametes: ab ab ab
Offspring according to independent assortment:
AaBb Aabb aaBb aabb
1 : 1 : 1 : 1
(Parental) (Recombinants) (Parental)
Since parental percentage is more than recombinants, it is due to linkage between genes A and B.

Asked in: NEET 2016 (Phase 1)

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