Question

Explain the inheritance of one gene with reference to stem height of Garden pea plant.

Answer 1

Gregor Mendel often regarded as the father of Genetics was the first systematic researcher in the field of genetics. Through his experiments and studies on garden pea plants, he uncovered the mysteries and key principles of heredity as well as the fundamental law of inheritance.

Complete answer:
Mendel began to conduct his experiments in 1856 on plant hybridization with garden peas (Pisum sativum) in the monastery garden. He proposed the Law of Segregation based on his experiments that showed the clear-cut differences in morphological characters by segregating a single gene during inheritance. The garden pea (Pisum sativum) which is used in his experiments contributed success by offering several advantages. He called the term “dominant trait” for the tall character which dominated and visible in the $F1$ generation, and “recessive trait” for the character of dwarfness which existed in hidden (latent) form in the $F1$ generation.
Mendel crossed a true pure breeding tall pea plant (TT) along with a true pure breeding dwarf pea plant (tt). In the $F1$ generation, the hybrids possess dominant character because all the offspring were tall (Tt). This indicated that dominance of tallness factor over dwarfness.
When he allowed the two $F1$ hybrids (Tt) to self-cross, then a variety of plants (TT, Tt, tT, tt) are obtained in $F2$ generation in an approximate ratio of 3:1. Both tall and dwarf plants are found in the $F2$ progeny in the ratio of 3 Tall plants (TT, Tt, tT) : 1 Dwarf plant (tt).

Note: Dihybrid cross refers to a cross between two different genes of pure parents that differ in two traits or character such as colour of cotyledons and texture of seed. When the tall plant with purple flower (TW) and dwarf plant with white flowers (tw) are self-crossed, then according to Mendel’s Law of Independent Assortment, the result of dihybrid cross is in the phenotypic ratio of 9:3:3:1.