Instructions: • Answer the questions based on your knowledge of the first law of Mendel. • Keep the presentation of your homework ordered and clean. • Do it yourselve, do your best and ask questions during the next class. It is your knowledge and understanding what matters. DBQ: coat color in the house mouse In the early years of the 20th century, many crossing experiments were done in a similar way to those of Mendel. The French genetist Lucien Cuénot used the house mouse, Mus musculus, to see whether the principles that Mendel had discovered also operated in animals. He crossed normal grey-colored mice with albino mice. The hybrid mice that were produced where all grey. These grey hybrids were crossed together and produced 198 grey and 72 albino offspring. 1. Calculate the ratio between grey and albino offspring, showing your working (2) 2. Deduce the color of coat that is due to a recessive allele, with two reasons for your answer (2) 3. Choose suitable symbols for the alleles for grey and albino coat and list the posible genotypes of mice using your symbols, together with the phenotype and each genotype (3) 4. Using hte headings shown to the right, explain how the observed ratio of grey and albino mice was produced (5) 5. Suggest how one gene can determine wheter the mice had grey fur and black eyes or White fur and red eyes (2) Key to alleles: Parental phenotypes Parental genotypes Alleles in gametes Hybrid phenotype Hybrid genotype Alleles in gametes Genotypes and phenotypes of offspring of hybrid mice, shown using a punnett grid.