Question

In a Mendelian monohybrid cross, which generation is always completely homozygous?
(a)${F}_{1}$ generation
(b)${F}_{2}$ generation
(c)${F}_{3}$ generation
(d)P generation

Answer 1

Hint: It is the first set of ancestors crossed. The Monohybrid cross is employed by geneticists to watch how homozygous offspring express heterozygous genotypes inherited from their parents.

Complete answer:
Hybridization may be a cross between two organisms with different variations at one genetic chromosome of interest. The character(s) being studied during a hybridization are governed by two or multiple variations for one locus.
A cross between two parents possessing a pair of contrasting characters is understood as hybridization. To hold such a cross, each parent is chosen to be homozygous or true breeding for a given trait (locus). Parents are pure homozygous TT (Tall) when crossed with Tt (Dwarf), it will give Tt (Heterozygous tall) in the ${F}_{1}$ generation. On selfing with heterozygous tall (Tt ) with (Tt). In the ${F}_{2}$ generation, we will get TT, Tt, Tt, tt. We get a phenotypic ratio- 3 tall: 1 dwarf. And genotypic ratio- 1 homozygous tall: 2 heterozygous tall: 1 homozygous recessive. Therefore the parent generation is usually homozygous, that is TT or tt.

Additional Information: Generally, hybridization is employed to work out the dominance relationship between the two alleles. The cross begins with the parental generation. The parental generation (P) is that the first set of oldsters crossed. The ${F}_{1}$ (first filial) generation consists of all the offspring from the oldsters. The ${F}_{2}$ (second filial) generation is made up of the offspring from the cross of ${F}_{1}$individuals.

So, the correct answer is ‘P generation’.

Note: Mendel tested his hypothesis with a kind of backcross called a testcross. An organism has an unknown genotype which is one among two genotypes (like RR and Rr) that produce an equivalent phenotype. The results of the test identify the unknown genotype.