Q162 / 180 · NEET 2016 (Phase 1) · Zoology

In a testcross involving F1 dihybrid flies, more parental-type offspring were produced than the recombinant-type offspring. This indicates:

  • A
    The two genes are located on two different chromosomes
  • B
    Chromosomes failed to separate during meiosis
  • Correct answer
    C
    The two genes are linked and present on the same chromosome
  • D
    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.

Hence, the correct answer is option: 'C'.

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