What percentage of progeny carry recessive traits in the F2 generation of a typical monohybrid cross conducted by Mendel if the parents are pure lines for the character considered?
[ 1 mark]
What percentage of progeny carry recessive traits in the F2 generation of a typical monohybrid cross conducted by Mendel if the parents are pure lines for the character considered?
[ 1 mark]
The correct option is B 25%
Gregor Johann Mendel conducted experiments in garden pea (Pisum sativum).
A cross involving alternate forms of one trait is called a monohybrid cross. A trait is a specific characteristic of an organism.
A typical monohybrid cross conducted by Mendel is given below:
Pure lines are selected as parents. Pure lines are homozygous for the character considered in the cross. After crossing the parents, the resulting generation is called F1.
The F1 hybrids are allowed to undergo selfing to produce the F2 generation.
Below given is the monohybrid cross by considering the character height.
Tall trait is dominant over dwarf.
Allele for tall trait is T, allele for dwarf trait is t.
The parents considered in the cross are pure for tall and dwarf trait. They differ in one character. The rest of the characters are same in both of them.
The representation of the monohybrid cross is as follows: -
Genotypic ratio in F2 generation -
TT : Tt : tt = 1 : 2 : 1
Phenotypic ratio in F2 generation -
Tall plants : Dwarf plants = 3 : 1
⇒ Out of 4 plants, no. of dwarf plants = 1
⇒ Out of 100 plants, no. of dwarf plants =14×100=25
Hence, 25% of plants in the F2 generation will be dwarf. So option b is correct.
Gregor Johann Mendel conducted experiments in garden pea (Pisum sativum).
A cross involving alternate forms of one trait is called a monohybrid cross. A trait is a specific characteristic of an organism.
A typical monohybrid cross conducted by Mendel is given below:
Pure lines are selected as parents. Pure lines are homozygous for the character considered in the cross. After crossing the parents, the resulting generation is called F1.
The F1 hybrids are allowed to undergo selfing to produce the F2 generation.
Below given is the monohybrid cross by considering the character height.
Tall trait is dominant over dwarf.
Allele for tall trait is T, allele for dwarf trait is t.
The parents considered in the cross are pure for tall and dwarf trait. They differ in one character. The rest of the characters are same in both of them.
The representation of the monohybrid cross is as follows: -
Genotypic ratio in F2 generation -
TT : Tt : tt = 1 : 2 : 1
Phenotypic ratio in F2 generation -
Tall plants : Dwarf plants = 3 : 1
⇒ Out of 4 plants, no. of dwarf plants = 1
⇒ Out of 100 plants, no. of dwarf plants =14×100=25
Hence, 25% of plants in the F2 generation will be dwarf. So option b is correct.
