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?
Correct answer: B. All round yellow
- 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.
This question appeared on the UHS MDCAT 2025 paper, which you can sit online with every answer explained.
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About Mendel's Laws of Inheritance
Mendelian inheritance explains how alleles separate into gametes and assort during reproduction, producing predictable genotype and phenotype ratios. Questions cover dominance, recessiveness, homozygous and heterozygous conditions, the laws of segregation and independent assortment, monohybrid and dihybrid crosses, test crosses and the limits caused by linked genes.
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