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Question
Given below is a schematic representation of the inheritance of the shape of the seeds of garden peas. Answer the questions that follow:
- Which is the dominant and recessive allele of the trait?
- What does the ratio 3 : 1 in the F2 generation represent?
- State Mendel's Law of Dominance.
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Solution
- The dominant allele is R (for round seeds), while the recessive allele is r (for wrinkled seeds). This is obvious because only round seeds develop in F1, whereas the wrinkled characteristic is entirely concealed.
- 3:1 indicates that three of the four seeds are spherical and one is wrinkled. That is, 75% of the F2 progeny have round seeds (the dominant characteristic), but only 25% have wrinkled seeds (the recessive trait).
- Mendel's law of dominance states that if an organism has two distinct alleles for a trait, the dominant allele will be expressed, hiding the recessive allele. This means that only the dominant allele determines the organism's phenotype.
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