Question

Following are the observations of Morgan’s dihybrid cross. Fill in the blanks with the most appropriate findings.
1. The genes responsible for white eye color and that for yellow body were very ____i____ linked. _____ii____ of the $F_2$ generation had parental phenotype while __iii_______ of $F_2$ offspring had the recombinant phenotype.
2. The genes responsible for white eye color and miniature wings were ___iv_____ linked. Percentage of $F_2$ progenies showing parental and recombinant phenotypes were ____v_____ and ____vi_____ respectively.

• A. i-tightly, ii-1.3%, iii-37.2%, iv-loosely, v-62.8%, vi-98.7%
• B. i-loosely, ii-1.3%, iii-98.7%, iv-loosely, v-62.8%, vi-37.2%
  
• C. i- tightly, ii-98.7%, iii-1.3%, iv-loosely, v-62.8%, vi-37.2%
• D. i-loosely, ii-98.7%, iii-37.2%, iv-loosely, v-62.8%, vi-1.3%

Answer 1

The correct option is C i- tightly, ii-98.7%, iii-1.3%, iv-loosely, v-62.8%, vi-37.2%

T.H. Morgan conducted his experiment on Drosophila melanogaster (commonly known as fruit fly). He carried out several dihybrid crosses using Drosophila to study the pattern of inheritance of certain genes. The crosses were similar to the dihybrid crosses carried out by Mendel in peas, however, the outcomes were quite different.
Morgan conducted a dihybrid cross for the following pairs of characters in Drosophila:-
A. Flies with wild type and mutant phenotypes for body colour and eye colour.
B. Flies with wild type and mutant phenotypes for eye colour and wing size.
$\begin{array}{ccccc}\text{Character}& \text{Wild type trait}& \text{Allele}& \text{Mutant trait}& \text{Allele}\\ \text{Body-colour}& \text{Brown}& y^{+}& \text{Yellow}& \text{y}\\ \text{Eye colour}& \text{Red}& w^{+}& \text{White}& \text{w}\\ \text{Wing size}& \text{Normal}& m^{+}& \text{Miniature}& \text{m}\end{array}$