Question

A plant breeder crossed a red flowered hibiscus plant with a yellow flowered hibiscus, and all of the offspring had orange flowers.

a) Of what type of inheritance is this an example? Provide the genotypes of the parents.

He then allowed the orange-flowered plants to self-fertilize.

b) Create a Punnett square and predict the genotypes AND phenotypes of the offspring from the orange-flowered plants.

Answer 1

Answer : 1) The type of inheritance shown in this case is that of an incomplete dominance.

we can have four possibilities. They are :-

a) Red flower (red is dominant to yellow) , b) Yellow flower (yellow is dominant to red),

c )Red and Yellow flower (co-dominance), d )Orange flower (incomplete dominance).

Given, Red and Yellow hibiscus makes Orange colour flowers.

Now from the question, we see all the offsprings are orange in colour (RY genotype), it means the parents must have been RR and YY genotypes. Thus,  the only way we can get all RY offspring is if the parents are RR and YY.

2 ) On crossing the offspring from the orange flower plant( two RY) , we get the following punnett square:

R Y

R RR RY

Y    RY YY

Genotype - 1:2:1 ( RR- 25 %, RY- 50% , YY - 25% )

Phenotype ratio - 3:1 ( Red : Yellow)