alleryStart learning →A Yy pea plant is self-crossed. What genotypic ratio of YY to Yy to yy is expected?
A3 to 1 to 0
B1 to 1 to 1
C2 to 1 to 1
D1 to 2 to 1
Answer & Solution
Correct answer: D. 1 to 2 to 1
1. Each Yy parent makes two kinds of gamete in equal numbers, Y and y.
2. Draw a two by two square with Y and y along the top and Y and y down the side.
3. The four boxes are YY, Yy, yY and yy.
4. The two heterozygous boxes are genetically the same, so they are grouped together.
5. Counting the boxes gives 1 YY, 2 Yy and 1 yy, a ratio of 1 to 2 to 1.
_Source: OpenStax Biology (1st ed., CC BY 4.0), Ch 12 "Mendel's Experiments and Heredity", section 12.2 Characteristics and Traits_
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