CBSE Class 12-science Answered

Limitations of dihybrid cross:

• Co-dominance between two dominants coming together as seen in blood group inheritance.
• Occurrence of non-allelic gene interaction like epistasis, inhibiting factors, presence of comple­mentary gene and additive factors, etc.
• Linkages between closely situated genes.
• Non-disjunctions (non-separation of homologous chromosomes) of chromo­somes during the time of formation of gametes.
• Multiple factor that may or may not be allelic, for a single trait (e.g. skin color, height and weight of human) and their inheritance.
• Pleiotropic effect of a gene i.e. a gene having influences on more than one trait.
• Allelism i.e. the presence of a series of alternative genes at a given locus in a chromosome.
• Presence of a lethal gene, i.e. an allele of a gene that renders inviable an organism.