In a testcross involving F1 dihybrid flies, more parental – type offspring were produced than the recombinant – type offspring. This indicates:
Answer: (C) The two genes are linked and present on the same chromosome. Answer: (C) The two genes are linked and present on the same chromosome Solution: When two genes lie on the same chromosome they tend to be inherited together (linkage), so a testcross of an F1 dihybrid yields more parental-type than recombinant-type offspring.
- 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
Correct Answer
(C) The two genes are linked and present on the same chromosome
Solution & Explanation
Answer: (C) The two genes are linked and present on the same chromosome Solution: When two genes lie on the same chromosome they tend to be inherited together (linkage), so a testcross of an F1 dihybrid yields more parental-type than recombinant-type offspring. Morgan called this physical association of genes on a chromosome 'linkage', and the higher proportion of parental combinations is its signature. NCERT Reference: NCERT Class XII, Ch 4, p.67, lines 34-39: "when the two genes in a dihybrid cross were situated on the same chromosome, the proportion of parental gene combinations were much higher than the non-parental type. Morgan attributed this due to the physical association or linkage of the two genes and coined the term linkage"