A geneticist who uses a carnivorous picther plant as a model

A geneticist who uses a carnivorous picther plant as a model plant makes the following corss. she proceeds to take a wild type pure-breeding female pitcher trisomic for chromosome 2 and crosses it to a normal dipoloid male picther plant that is homozygous for a recissive mutation (v) that makes it hungry all the time (the super hungry mutant). A trisomic F1 plant is then back-crossed to the super-hungry male parent. From this cross:
a) what is the ratio of the normal pitcher plants to those that are super hungry when you assume that v is located on chromosome 2?
b) what is the ratio of normal pitcher plants to those that are super hungry when you assume that v is located on chromosomes 2?

Solution

Answer:

a). 1:1

Explanation:

VV+1 (wild)   x (super hungry plant) vv---Parents

V, V+1                     v -----------------------------Gametes

Vv (wild), V+1v (trisomic wild)-----F1

V+1v x vv-----------Back cross

v

V+1

V+1 v (50%)

v

vv (50%)

The normal pitcher plants are 50% and super hungry plants are 50%.

Normal (1) : Super hungry pitcher plants (1)