Explain the monohybrid cross, with a diagram and describe the interpretation of Mendel on monohybrid cross.

Explanation

Crosses involving inheritance of only one pair of contrasting characters are called monohybrid cross. It is a cross between two forms of a single trait like a cross between tall and dwarf plant. In monohybrid cross, a pure breeding all plant and a pure breeding dwarf plant, results, tall and monohybrids in `F_(1)` generation.
In `F_(2)` generation, selfing of the `F_(1)` monohybrids resulted in tall and dwarf plants in the ratio of 3:1. External expression of a particular trait is known as phenotype. So the phenotypic ratio is 3:1.
In the `F_(2)` generations 3 different types were obtained.
Tall Homozygous - TT (pure) - 1
Tall Heterogygous - Tt - 2
Dwarf Homozygous - tt - 1
So the genotypic ratio 1:2:1. A genotype is the genetic expression of an organism.
Mendel.s interpretation on monohybrid cross:
Factors are passed on from one generation to another, factors are referred as genes. Tallness and dwarfness are determined by a pair of contrasting factors tall plant T, a dominant character and a plant is dwarf .t., recessive character in pairs. Pure breeding tall plants (TT) and pure dwarf plants (tt) are called homozygous. If they are unlike, (Tt) they are referred as heterozygous.
(i) Two factors make up a pair of contrasting characters are called alleles or alleomorphs. One member of each pair is contributed by one parent.
(ii) When two factors of a trait are brought together, by fertilization, only one expresses itself (tallness), masking the expression of the othe (dwarfness). The character which express itself is called dominant and the character, which is masked is called recessive.
(iii) The factors for tallness [T] adn dwarfness (t) are separate entities, and in a gamete either T or t is present. When `F_(1)` hybrids are self crossed the two entities separate and then unite independently, forming tall and dwarf plants.