Question

In the garden pea Pisum sativum, round pea texture (R) is dominant over wrinkled pea texture (r). A female that is homozygous recessive for pea texture is crossed to a male that is heterozygous for pea texture. Please answer the following questions (show your calculations):

1. A) genotype of the female (1 point)

B) list the types of gametes the female can produce (2 points)

C) do the cross in a Punnett square (4 points).  

D) What is the phenotypic ratio of the cross? (1 point)

Answer 1

A)

Answer –

As, given in the question the allele for round pea texture (R) is dominant over allele for wrinkled pea texture (r). Also, homozygous recessive pea female (rr) is crossed to a heterozygous male (Rr).

Therefore, the genotype of female is rr.

B)

Answer –

As the female has a genotype of rr. Then, she can only make gametes with genotype r.

Therefore, the female can produce only one type of gamete with genotype r.

C)

Answer –

The following cross occurs

Parent genotype                Homozygous recessive, female    X    Heterozygous male

Parent genotype                                                       rr             X             Rr

Gamete genotype                                                     r              X          R       r

Offspring – Punnett square

Female/male gametes	R	r
r	Rr Round-pea	Rr Wrinkle-pea

D)

Answer –

From the Punnett square,

Phenotypic ratio – Round-pea: Wrinkled-pea = 1:1