In a test cross involving \(F_1\) dihybrid flies, more parentaltype offspring were produced than the recombinanttype offspring. This indicates

A the two genes are linked and present on the same chromosome
B both of the characters are controlled by more than one gene
C the two genes are located on two different chromosomes
D chromosomes failed to separate during meiosis.

Verified Solution

Answer & Solution

Correct Answer

(A) the two genes are linked and present on the same chromosome

Step-by-step Solution

Detailed explanation

(a): If in a dihybrid test cross more parental combinations appear as compared to the recombinants in \(F_2\) generation, then it is indicative of involvementof linkage. Linkage is the tendency of two differentgenes on the same chromosome to remain together during the separation of homologous chromosomes at meiosis. During complete linkage no recombinants are formed whereas in incomplete linkage few recombinants are produced along with parental combinations.

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.

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In a test cross involving \(F_1\) dihybrid flies, more parental­type offspring were produced than the recombinant­type offspring. This indicates

Step-by-step Solution

In a test cross involving \(F_1\) dihybrid flies, more parentaltype offspring were produced than the recombinanttype offspring. This indicates