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Course: Middle school biology - NGSS  > Unit 7

Lesson 5: Reproduction and genetic variation
Science
Middle school biology - NGSS
Inheritance and variation
Reproduction and genetic variation
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Problem

In a population of pea plants, some plants have yellow seeds and others have green seeds. The gene for seed color has two possible alleles. One allele is for yellow seeds (Y), and the other allele is for green seeds (y).
The Punnett square below models the results of a cross between two pea plants. One of the plants is homozygous for green seeds (yy). The other plant is heterozygous (Yy).
A Punnett square shows a square with four boxes filled in with genotypes. Across the top of the square from left to right are lowercase y and lowercase y. Along the left side of the square from top to bottom are uppercase Y and lowercase y. The filled-in boxes of the square show the following genotypes. Top-left box: uppercase Y and lowercase y. Top-right box: uppercase Y and lowercase y. Bottom-left box: lowercase y and lowercase y. Bottom-right box: lowercase y and lowercase y.
What is the expected ratio of offspring with yellow seeds to offspring with green seeds?
Choose 1 answer: