MENDEL'S LAWS OF INHERITANCE (CBSE 10TH BIOLOGY)

• Gregor Johann Mendel, known as the Father of Genetics, proposed two fundamental laws based on his experiments with pea plants.

• Law of Dominance

• Definition: In a pair of contrasting traits, only one trait (dominant) is expressed in the F₁ generation, while the other (recessive) remains hidden.
• Example:
• Cross between pure tall (TT) and pure dwarf (tt) pea plants:
• F₁ generation: All plants are tall (Tt) because tallness is dominant over dwarfness.

• Law of Segregation (Law of Purity of Gametes)

• Definition: During the formation of gametes, the two alleles of a gene segregate (separate) from each other so that each gamete receives only one allele.
• Example:
• In F₁ plants (Tt), the gametes formed will carry either T or t, not both.
• Selfing of F₁ (Tt × Tt) gives F₂ generation with genotypes: TT, Tt, tT, tt (in 3:1 ratio phenotypically).

Monohybrid Cross Summary:

• Generation	Cross	Genotype	Phenotype
  P (Parents)	TT × tt	Tall × Dwarf	—
  F₁	Tt	All Tall	100% Tall
  F₂	Tt × Tt	TT, Tt, tt	3 Tall : 1 Dwarf