4. An agricultural geneticist who uses Nepenthes distillatoria (the carnivorous

Question

4. An agricultural geneticist who uses Nepenthes distillatoria (the carnivorous pitcher plant) as a model plant makes the following cross. She proceeds to take a wild type pure-breeding female pitcher plant trisomic for chromosome 2 and crosses it to a normal diploid male pitcher plant that is homozygous for a recessive 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 normal pitcher plants to those that are super hungry when you assume that v is located on chromosome 2? (2.5 marks) B] What is the ratio of normal pitcher plants to those that are super hungry when you assume that v is not located on chromosome 2? (2.5 marks)

Explanation / Answer

In F1 generation, the picher plant is heterozygous for trisomic and heterozygous for mutation (v). When you made back cross with super-hunger male parent,

a) The ratio of normal pitcher plants to those that are super hungry is 1:1 when you assume that v is located on chromosome 2

b) The ratio of normal pitcher plants to those that are super hungry is 1:1 when you assume that v is not located on chromosome 2

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