[Campbell Biology P.345] WHAT IF? Suppose the eye color gene in Morgan's experiment were loc... | Practice Question

WHAT IF? Suppose the eye color gene in Morgan's experiment were located on an autosome instead of the X chromosome. What would be the expected phenotypic outcome in the F2 generation?

  • A: The results would be identical to what Morgan observed.
  • B: A 3:1 ratio of red-eyed to white-eyed flies, with the white-eyed trait appearing in both males and females.
  • C: A 1:1 ratio of red-eyed to white-eyed flies.
  • D: All offspring would have red eyes.

Explanation

If the gene were on an autosome, it would follow standard Mendelian inheritance patterns, independent of sex. The F1 generation would be heterozygous Ww . A cross between two F1 heterozygotes Ww x Ww would produce offspring with genotypes in a 1 WW : 2 Ww : 1 ww ratio, and phenotypes in a 3 dominant red-eyed : 1 recessive white-eyed ratio. Crucially, this 3:1 ratio would be expected in both males and females.