Biology 0610 · IGCSE · Chromosomes, genes and proteins

Chromosomes, genes and proteins — practice question

Fruit flies may have either red eyes or white eyes. This is a sex-linked characteristic, and the gene controlling eye colour is found on the X chromosome. The allele for red eyes ($R$) is dominant over the allele for white eyes ($r$). A fruit fly with genotype $X^R X^r$ was crossed with a fruit fly with genotype $X^R Y$. What percentage of the offspring will have red eyes?

  • A$25\%$
  • B$50\%$
  • C$75\%$
  • D$100\%$

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