Biology - Principles of Inheritance and Variation Question with Solution | TestHub

In pea plants, tallness ($T$) is dominant over shortness ($t$), and green pod colour ($G$) is dominant over yellow pod colour ($g$).

The cross is between a pure tall plant with yellow pods ($TTgg$) and a pure short plant with green pods ($ttGG$).

The $F_1$ generation will have the genotype $TtGg$, which corresponds to tall plants with green pods.

Upon selfing the $F_1$ generation ($TtGg\times TtGg$), the $F_2$ generation is produced.

The phenotypic ratio of the $F_2$ generation in a dihybrid cross is $9:3:3:1$, which represents:
$9$ Tall, Green pods
$3$ Tall, Yellow pods
$3$ Short, Green pods
$1$ Short, Yellow pod

The double recessive phenotype is the short plant with yellow pods ($ttgg$).

Out of $16$ possible combinations in the $F_2$ generation, only $1$ plant is double recessive.

Answer: One