Question

Tallness (T-) is dominant over dwarfness (tt) while red flower colour (R-) is dominant over white colour (rr). A plant with genotype TtRr is crossed with a plant of genotype ttrr. Percentage of progeny having tall plants with red flowers is
A)25%
B)50%
C)75%
D)100%

Answer 1

Mendel conducted and performed artificial pollination or cross-pollination experiments using several true-breeding pea lines A true breeding line is defined as the one that having undergone continuous self-pollination, shows the stable trait inheritance and expression for several generations.

Complete answer:
Mendel selected a total of 14 true-breeding pea plant varieties, such as the height of the stem whether tall or dwarf as pairs which were similar except for one character with contrasting traits. It means, Mendel selected 7 characters that are seed shape, seed colour, pod colour in pea plant for carrying out hybridization experiments and to study inheritance.
Tallness (T-) and red flower colour (R-) are said to be dominant over dwarfism (t) and white colour (r) respectively. The occurrence of single copies of T and R alleles produce and synthesize tall plants with red flowers (T-R-) while dwarf plants with white flowers are obtained from genotypes “ttrr” only.

Phenotypic ratio that comes will be = 1 tall plant with red flowers: 1 tall plant with white flowers: 1 dwarf plant with red flowers: 1 dwarf plant with white flowers; so, the percentage of tall and red flowered progeny is, $\dfrac{1}{4}$= 25%.

Hence, the correct answer is option (A)

Note: In a typical test grows an organism that shows are dominant. Phenotype is closed with that of the recessive parent. Instead of doing the self-pollination, the progenies that come from such across can be easily analysed to predict the genotype of the test Organism. If we want to determine the Genotype of oil it flowered pee planted, it is crossed with recessive parent white flowered. People rant instead of self-crossing.