[Campbell Biology P.890] Some plant species produce male individuals with an XY genotype and... | Practice Question

Some plant species produce male individuals with an XY genotype and female individuals with an XX genotype. After double fertilization, in a cross between a male XY and a female XX plant, what would be the genotypes of the embryos and endosperm nuclei?

  • A: embryo XY/endosperm XXX or embryo XX/endosperm XXY
  • B: embryo XX/endosperm XX or embryo XY/endosperm XY
  • C: embryo XX/endosperm XXX or embryo XY/endosperm XYY
  • D: embryo XX/endosperm XXX or embryo XY/endosperm XXY

Explanation

Male XY individuals produce X and Y sperm n . Female XX individuals produce X eggs n and XX polar nuclei 2n . In double fertilization, one sperm fertilizes the egg, and the other sperm fertilizes the polar nuclei. Therefore: If an X sperm fertilizes an X egg, the embryo is XX. The other X sperm fertilizes the XX polar nuclei, so the endosperm is XXX. If a Y sperm fertilizes an X egg, the embryo is XY. The other Y sperm fertilizes the XX polar nuclei, so the endosperm is XXY. Thus, the possible embryo/endosperm pairs are XX embryo/XXX endosperm or XY embryo/XXY endosperm .