Question

In fruit flies, long wing is dominant to vestigial wing. When heterozygous long-winged flies were crossed with vestigial-winged flies, $192$ offsprings were produced. If an exact Mendelian ratio had been obtained, then the number of each phenotype would have been

	Long-winged	Vestigial-winged
(a)	$64$	$128$
(b)	$96$	$96$
(c)	$128$	$64$
(d)	$192$	$0$

• A. a
• B. b
• C. c
• D. d

Answer 1

Answer: (B)

A cross between heterozygous long-winged flies and (homozygous) vestigial winged flies represents an example of test cross, in which the exact Mendelian ratio of $1:1$ is obtained, i.e. $96$ long-winged flies and $96$ vestigial winged flies.