Mendel crossed a plant with round yellow seeds (RRYY) and a plant with wrinkled green seeds (rryy), what was the phenotype of all F1 offspring?

  • A. All round green
  • B. All round yellow
  • C. All wrinkled yellow
  • D. All wrinkled green

Explanation

Every offspring receives R and Y from one parent and r and y from the other, so all are RrYy and both dominant characters show, giving round yellow seeds. The recessive wrinkled and green phenotypes reappear only in the F2, in the familiar 9:3:3:1 ratio. This uniform F1 is what Mendel's law of dominance describes.

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