Question

a) Workout across up to F2 generation between two pure breeds plant one bearing Violet Flowers and the other bearing white Flowers.
b) Name this type of cross.
c) State the different law of Mendel that can be derived from such a cross.

Answer 1

Mendel worked on Pisum sativum for 7 year and proposed the law of inheritance in living organisms. Mendel proposes two general rules: the first law or Law of dominance and the second Law or law of segregation. Mendel worked on pisum sativum considering seven contrasting traits as pod color , seed shape , flower color , pod color , flower position , plant height , and told about recessive and dominant traits.

Complete answer:
a) According to the question the cross is made between the violet flower (VV) and white flower (vv)
F1 generation- VV X vv
The gametes produced are V X v respectively.
The offspring produced in the F1 generation is Vv or the violet flower. (considering violet as dominant).
Then the cross is again done between F1 hybrids Vv X Vv

| V| v
---|---|---
V| VV (violet)| Vv (violet)
v| Vv (violet)| Vv(white)

The F2 generation obtained as a result of the cross – Three violets and 1 white.
The phenotypic ratio as a result of the cross is 3:1
The genotypic ratio is 1:2:1

b)The cross which involves only one trait is known as monohybrid cross. This type of cross is termed as monohybrid cross.

c) LAW OF DOMINANCE: - It states that in a heterozygote, the character which is expressed is known as the dominant trait and the one which remains unexpressed is the recessive trait. In this case violet is dominant over white.
LAW OF SEGREGATION: - This law is based on the fact that the two factors of a character present in an individual do not get mixed up and both the traits are recovered as such in the F2 generation. This law defines the purity of gametes.
Note: The observable characteristics of an individual is known as its phenotype whereas the genetic makeup of an individual is called its genotype. The alleles located on the chromosome are responsible for the expression of a particular trait. Mendel proposed the genotypic and phenotypic ratio of monohybrid cross as 1:2:1 and 3:1.