Question

Study the given table and answer the following questions:

Parents	F1	F2
A pea plant with red flowers was crossed with a pea plant with white flowers.	30 seeds were sown and all bore plants with red flowers.	44 seeds were sown, 33 plants bore red flowers and 11 plants bore white flowers.

1. Depict the information given in the table in the form of a cross.
2. Deduce the F₂ phenotypic ratio/F₂ ratio showing external look aв well as genotypic/genetic makeup, ratio.

Answer 1

a. To depict the cross, let us assume:

R = Dominant allele for red flowers

r = Recessive allele for white flowers

For parental generation (P):

Phenotype: Red flower × White flower

Genotype: RR × rr

Gametes: (R) and (r)

For the first filial generation (F₁​):

Genotype: Rr (Heterozygous Red)

Phenotype: All Red flowers (30 plants)

Selfing of F₁​ (Rr × Rr):

Gametes: (R), (r) and (R), (r)

For the second filial generation (F₂​):

Gametes	R	r
R	RR	Rr
r	Rr	rr

b. Based on the F₂​ data provided (33 red and 11 white plants) and the Punnett square above, we can deduce the following:

F₂ phenotypic ratio (External look):

This ratio is based on the observable physical traits.

Red flowers : White flowers

33 : 11

The simplified Ratio is 3 : 1.

F₂ genotypic ratio (Genetic makeup):

This ratio is based on the genetic combinations (RR, Rr, and rr).

Pure Red (RR) : Hybrid Red (Rr) : Pure White (rr)

According to Mendelian principles for a monohybrid cross:

The ratio is 1 : 2 : 1.