Gene Mapping The fact that Gregor Mendel decided to study pea plants was a stroke of sheer luck Not only is it a simple organism to study but the characteristics he studied assorted independently from each other which allowed him to create the foundation of modem genetics Let s quickly review independent assortment using a hypothetical plant species that has a diploid number of 4 2n 4 For this plant seed texture and plant height are controlled by two different genes Seed texture can either be rough R or smooth r and plant height can either be tall T or short t We will assume independent assortment meaning the genes for seed texture and height are on separate chromosomes the gene for seed texture is on chromosome 1 and the gene for plant height is on chromosome 2 A cross is performed between a RRTT parent and a rrtt parent 1 Predict the genotypes of the F1 progeny T Chromosome 1 R Xa 2 Using the four cells below determine the possible products of meiosis that would be generated by the F progeny the first one has been done for you OO Chromosome 2 Next a testcross is performed between an F1 individual and an individual that is rtt Use the space below to perform the cross Identify the possible phenotypes and their ratios in the offspring