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) crossed with White terminal (vvaa).
- Gametes: Parent 1 (VVAA) produces VA gametes. Parent 2 (vvaa) produces va gametes. 
- F\textsubscript{1 Generation:} All offspring are heterozygous (VvAa) and exhibit violet axial flowers. 
- F\textsubscript{2 Generation (Punnett Square):} 
 

- Phenotypic Descriptions in F\textsubscript{2}:
  - 9 Violet axial: Plants with dominant alleles for both flower colour (V) and position (A).
  - 3 Violet terminal: Plants with dominant flower colour allele (V) and recessive position alleles (aa).
  - 3 White axial: Plants with recessive flower colour alleles (vv) and dominant position allele (A).
  - 1 White terminal: Plants with recessive alleles for both flower colour (vv) and position (aa). 
- Phenotypic Ratio in F\textsubscript{2}: 9:3:3:1. 
- Mendel’s Law of Inheritance Demonstrated: Law of Independent Assortment: Alleles for distinct genes segregate independently during gamete formation, resulting in novel trait combinations.