Question

If $F_2$ generation of a Mendelian dihybrid cross $(TTRR\times ttrr)$ takes

• A. Tall plants and violet flowered plants are obtained in $1:1$ frequency
• B. Ratio of parental and non-parental plants is $1:15$
• C. Recombinant plants are obtained in $1:1$ frequency
• D. Both A and C

Answer 1

The correct option is A Tall plants and violet flowered plants are obtained in $1:1$ frequency

In the given question, tall plants (T) are dominant over short plants (t). Similarly, violet flowers (R) are dominant over white flowers (r). The gametes produced by TTRR and ttrr plants will be TR and tr respectively. The genotype of offsprings of F${}_1$ generation will be TtRr and phenotype will be tall and violet flowered plants. When this F${}_1$ is crossed, the F${}_2$ generation will have phenotypic ratio of 9:3:3:1 where 9 parts are tall and violet flowered plants, 3 parts are tall and white flowered plants, 3 are short and violet flowered plants and 1 part is short and white flowered plants. Hence, in F${}_2$ generation, 12 parts will be tall and 12 parts will violet flowered plants. That is their frequency will be 1:1. The ratio of parental plants (tall and violet flowered and short and white flowered) and non-parental plants (tall and white flowered and short and violet flowered) will be 10:6.

Thus, the correct answer is 'Tall plants and violet flowered plants are obtained in 1:1 frequency.'