Question

Define ${F_1}$ and ${F_2}$ generations.

Answer 1

Hint: To check the pattern of inheritance of a certain trait between two parental organisms and their offsprings, an analysis is done using a pedigree chart. The cross created in the chart gives rise to generations through which the inheritance pattern is deduced. Each generation can give rise to another generation and using the pedigree chart, the presence or absence of a trait is observed.

Complete answer:
${F_1}$ generation refers to the first filial generation and ${F_2}$ refers to the second filial generation in a pedigree analysis chart.
So, the first filial generation arises from the initial cross and consists of the offsprings of the parents. When the members of the first generation are crossed with other individuals or crossed among themselves, it results in the second filial generation.
Now let us understand this concept with the help of an example – Mendel’s pea experiment.
Gregor Mendel crossed a pure tall pea plant with a pure dwarf pea plant.
In the first filial generation, the phenotype of all plants was tall.
Then the pea plants of the first generation were crossed among themselves. This resulted in the formation of the second filial generation.
In the second generation, both tall and dwarf plants were produced in a 3:1 ratio respectively.

Note:
The following inferences were made by observing the inheritance pattern in the first and second generation:
> Tallness is a dominant trait.
> Dwarfness is a recessive trait.
Mendel made various other observations for different traits by conducting experiments on pea plants. He then came up with the following laws:
> Law of dominance
> Law of segregation
> Law of independent assortment