In Colias butterflies there is a rare allele which codes for an unusual stripe o
ID: 220675 • Letter: I
Question
In Colias butterflies there is a rare allele which codes for an unusual stripe on the forewing. The S allele acts as a dominant to produce the stripe but is a recessive lethal allele acting early in larval development. The gene is also located on the Z sex chromosome. (Remember, in butterflies females are the heterogametic sex.) Which of the following statements are true if a striped male and a normal female were crossed? Choose all that apply.
a half of the female offspring would be striped
b half of the male offspring would be striped
c the male parent must be heterozygous
d only males can be striped
e there would be half as many female offspring as male offspring
Explanation / Answer
If we consider the genotype
ZX - Stripped male..
XX - Normal female..
By doing the cross.. ZX * XX
The offspring are.
ZX (STRIPPED MALE).
ZX ( STRIPPED MALE)..
XX ( NORMAL FEMALE)..
XX (NORMAL FEMALE)..
The correct option are
(a) only males will be stripped..
(b) half as male and female offspring..
(c) equal no of cell to be produced