Question

On the planet, PSEG, Rhinoceros Beetles are chosen for leadership positions in government based on their ability to sing Beetle songs. Most Beetles cannot sing at all (wild-type). A single autosomal gene, FRANK, with alleles F(dominant) and f (wild-type) determines whether the individual beetles have this singing phenotype. In a cross between two singing Rhinoceros Beetles, a large F1 progeny is generated. The ratio of singing Beetles to non-singing Beetles in this progeny is 2:1, irrespective of gender. The most likely mode of inheritance for the singing phenotype is:

Answer 1

Answer:

homo-zygous lethal dominant

Explanation:

A homo-zygous lethal pattern is a type of inheritance where an allele is lethal in homo-zygous individuals. In normal dominance, the expected genotype ratio when F1 heterozygous individuals are crossed is 1:2:1 (i.e. 1 homo-zygous dominant: 2 heterozygous individuals and 1 homo-zygous recessive), while the phenotypic ratio is 3:1 (3 individuals expressing the dominant allele: 1 individual only expressing the recessive allele). In this case, the homo-zygous lethal allele changes the expected F2 phenotypic ratio to 2:1 (i.e., 2 heterozygous singing Beetles : 1 homo-zygous recessive non-singing Beetles), where the partially dominant allele is lethal in homo-zygous individuals.