question_answer

Differentiate between monohybrid cross and dihybrid cross.

Or

Explain how test cross helps in identifying the genotype of the organism.

Answer:

Differences between monohybrid cross and dihybrid cross are as follows

Monohybrid cross	Dihybrid cross
It is a cross between two individuals taking a single contrasting trait at a time.	It is a cross between two individuals taking two contrasting traits at a time.
It helps to study the inheritance of a pair of allele.	It helps to study the inheritance of two pairs of alleles.
The phenotypic ratio in \[{{F}_{2}}\]- generation is 3 : 1	Phenotypic ratio in \[{{F}_{2}}\]- generation is 9 : 3 : 3 : 1.
The genotypic ratio in \[{{F}_{2}}\]- generation is 1 : 2 : 1.	The genotypic ratio in \[{{F}_{2}}\]- generation is 1 : 2 : 1 : 2 : 4 : 2 : 1 : 2 : 1.
Or
Test cross is a type of cross made between unknown dominant genotype and the recessive parent. For example, when \[{{F}_{1}}\] hybrid (Tt) is crossed with or a pure dwarf plant (tt), 1 : 1 ratio is obtained among progenies.