Mendel's Hybridisation experiment

• Mendel selected 22 varieties of pea plant for his experiments.

• Mendel studied  total 7 characters of inheritance in which each character is having two contrasting forms but consider only one contrasting character at a time.

• He took a pure tall pea plant and pure dwarf pea plant and cross pollinated them. that is the pollen grains of tall plant are dusted over the stigma of Dwarf plant and vice versa.

• Plants produce from these generation were all tall.
  

• All plants of first generation were called first filial generation or F1 generation by Mendel.

• Now when tall plants of F1 generation are self pollinated and the seeds obtained  were sown then all plants were not tall but there were dwarf plants also.

• The phenotypic ratio of these tall plants and  dwarf plants was 3:1 that  is 75% plants were tall and 25% plants were dwarf.

• Offsprings obtained from F1 Generation were called second filial generation or F2  generation by Mendel.

• The genotype of 3 tall plants and 1 dwarf plant in F2 generation is

1 Pure Tall (TT)

2 Hybrid tall (Tt)

1 Pure dwarf (tt)

• And the genotypic ratio was 1:2:1

• Mendel drew some conclusions from his experiments:-

1. Whatever may be the parents, reciprocal crosses always gives same results. For example, In original or basic cross between tall male and dwarf female all F1 generation plants were tall and in reciprocal cross between dwarf male and tall female the F1 generation plants  were also tall.
2. Out of two contrasting characters, only one is expressed in F1 Generation and other remain hidden and on self pollinating plants of F1 generation, the hidden characters will reappeared in F2 generation.
3. This experiment all revealed that the dwarf character only remain hidden in F1 generation but not completely disappeared because they reappeared in F2 generation.

• Traits which appeared in F1 generation are called Dominant characters and the characters which is hidden in F1 generation and reappeared in F2 generation is called recessive character.