Question

The phenotypic ratio of trihybrid cross in F2 generation is?
A. \[27{\text{ }}:{\text{ }}9{\text{ }}:{\text{ }}9{\text{ }}:{\text{ }}9{\text{ }}:{\text{ }}3{\text{ }}:{\text{ }}3{\text{ }}:{\text{ }}3{\text{ }}:{\text{ }}1\]
B. \[9{\text{ }}:{\text{ }}3{\text{ }}:{\text{ }}3{\text{ }}:{\text{ }}1\]
C. \[1{\text{ }}:{\text{ }}4{\text{ }}:{\text{ }}6{\text{ }}:{\text{ }}4{\text{ }}:{\text{ }}1\]
D. \[27{\text{ }}:{\text{ }}9{\text{ }}:{\text{ }}3{\text{ }}:{\text{ }}3{\text{ }}:{\text{ }}9{\text{ }}:{\text{ }}1{\text{ }}:{\text{ }}2{\text{ }}:{\text{ }}1\]

Answer 1

Hint: A trihybrid cross is a cross between individuals of the same type who are heterozygous for three pairs of alleles at three different loci. The number of possible genotypic combinations is 64.

Complete Answer:
The F1 generation refers to the first generation of a cross between two parents. Filial generations are the designation given to successive sets of offspring. The letter 'P' is designated for the parent generation. The first set of offspring from these parents is known as the F1 generation. The generation of F1 can reproduce to create the F2 generation, and so on.
For a dihybrid cross, the phenotypic ratio is \[9{\text{ }}:{\text{ }}3{\text{ }}:{\text{ }}3{\text{ }}:{\text{ }}1\] .
The chart below represents a cross of F2 generation between organisms with genotype AaBbCc.

As shown in the figure the phenotypic ratio of a trihybrid cross in F2 ​generation will be \[27{\text{ }}:{\text{ }}9{\text{ }}:{\text{ }}9{\text{ }}:{\text{ }}9{\text{ }}:{\text{ }}3{\text{ }}:{\text{ }}3{\text{ }}:{\text{ }}3{\text{ }}:{\text{ }}1\] .
Thus, the correct answer is option A i.e., \[27{\text{ }}:{\text{ }}9{\text{ }}:{\text{ }}9{\text{ }}:{\text{ }}9{\text{ }}:{\text{ }}3{\text{ }}:{\text{ }}3{\text{ }}:{\text{ }}3{\text{ }}:{\text{ }}1\] .
Note: A monohybrid cross is a genetic mixture between two individuals who have homozygous genotypes or genotypes that have completely dominant or completely recessive alleles, resulting in opposite phenotypes for a certain genetic trait. The dihybrid cross is a cross between two organisms with two different observable traits.