The sex of birds, some insects, and other organisms is determined by a ZW chromosomal arrangement in which the males have like sex chromosomes (ZZ) and females are ZW (similar to XY in humans). Assume that a recessive lethal allele on the Z chromosome
causes death of an embryo in birds. What sex ratio would result in the offspring if a cross were made between a male heterozygous for the lethal allele and a normal female?
A) 4:1 male to female
B) 3:1 male to female
C) 2:1 male to female
D) 1:1 male to female
E) 1:2 male to female
Answer: C
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