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Q.
How many genotypes are represented only once in the Mendelian dihybrid $F_{2}$ generation?
NTA AbhyasNTA Abhyas 2020
Solution:
In Mendelian dihybrid cross homozygous dominant pea plant (Yellow, Round seeds) is crossed with homozygous recessive pea plant (green, wrinkled).
Parental genotype- $\left(\right.YYRR\left.\right)\times \left(\right.yyrr\left.\right)$
The $F_{1}$ generation of this cross produces Yellow, Round phenotype pea plant having genotype- $\left(\right.YyRr\left.\right)$
In $F_{2}$ generation number of progeny formed $=16$
The genotypic ratio of dihybrid cross is - $1:2:1:2:4:2:1:2:1.$
Hence, the genotype which appears only once is - $4$
