Question

(a) Work out a dihybrid cross up to F₂ generation between pea plants bearing violet-colored axial flowers and white-colored terminal flowers using Punnett’s square. Give their F₂ phenotypic ratio. State the Mendel’s law of inheritance that was derived from such a cross.

Hint:

The dihybrid cross demonstrates the Law of Independent Assortment, showcasing how genes for different traits segregate independently during gamete formation.

Answer 1

- Parents: Violet axial (VVAA) × White terminal (vvaa). 
- Gametes: Parent 1 (VVAA): VA. Parent 2 (vvaa): va. 
- F\textsubscript{1 Generation:} All offspring are heterozygous (VvAa), bearing violet axial flowers. 
- F\textsubscript{2 Generation (Punnett Square):} 
 

- Phenotypic Ratio: - 9 Violet axial: Plants with dominant traits for flower colour (V) and position (A). - 3 Violet terminal: Plants with dominant colour (V) and recessive position (aa). - 3 White axial: Plants with recessive colour (vv) and dominant position (A). - 1 White terminal: Plants with recessive traits for both colour (vv) and position (aa). 
- Phenotypic Ratio: 9:3:3:1. 
- Mendel’s Law of Inheritance Derived: Law of Independent Assortment: Alleles of different genes assort independently during gamete formation, leading to new combinations of traits.