Question

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
• C. The two genes are linked and present on the same chromosome
• D. Both of the characters are controlled by more than one gene

Answer 1

Answer: (C)

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.