Question

A test cross of $F_1$ flies ++/cd produced the following offspring :

$++/cd$	$8$
$cd/cd$	$8$
$+c/cd$	$42$
$c+/cd$	$42$

This cross represents.

• A. Trans arrangement
• B. No crossing over
• C. Cis arrangement
• D. Complete linkage

Answer 1

The correct option is B No crossing over

Since recombination frequency is directly proportional to distance between genes, the values are used to locate genes on a chromosome number. Here the parental genotype is =c/=d. Presence of both wild type and mutant alleles of a gene on the same chromosome is known as trans arrangement. Here, the genes are in trans arrangement.