Question

In maize, coloured endosperm (C) is dominant over colourless (c) and full endosperm (R) is dominant over shrunken (r). When a dihybrid of $F_1$ generation was test crossed, it produced four phenotype in the following percentage
Coloured and Full = 45%
Coloured - Shrunken = 5%
Colourless - Full = 4%
Colourless - Shrunken = 46%
From these data what would be distance between the two allelic genes

• A. 48 units
• B. 9 units
• C. 4 units
• D. 12 units

Answer 1

The correct option is B 9 units

Distance between the two allelic genes
= Percentage of recombinant offsprings
= Percentage of Coloured – Shrunken offspring + Percentage of Colourless – Full offspring
= 5 + 4 Map units
= 9 Units
(Here recombinant offspring means different than $F_1$ and $F_2$.)