Year 13 Inherited change 11 1a. Construct a genetic diagram to predict the genotype and phenotypes of the offsprings produced by a cross between a short haired smooth coated guinea pig that is heterozygous for the hair length gene and a short haired, rough coated guinea pig that is heterogygous at both gene loci. A/a -length of hair, A- short hair a- long hair; B/b-type of hair ,B- rough hair,b- smooth hair A02 4 MARKS Click or tap here to enter text. (b) What are the expected ratios of the different phenotypes in the offsprings of this cross? AO1 2 MARKS Click or tap here to enter text. (c) Imagine that you have a guinea pig with short, rough hair. What type of guinea pig would you cross your short haired, rough guinea pig with to know its genotype? AO1 2 MARKS Click or tap here to enter text. / (d) Explain how you would use the offspring phenotypes to work out the genotype of the short, rough haired parent. You might want to use a genetic diagram to help your explanation. AO1 2 MARKS Click or tap here to enter text. 2 2.Below are the components that control the translation f the gene for B-galactosidase in the bacterium Escherichia coli. Number them as they are organised in the bacterial chromosome. AO1 1 MARKS Promoter for regulatory gene B- galactosidase Operator Promoter for structural gene regulatory gene 3 3.A plant with red flowers and serrated leaves which was heterozygous at both loci was crossed with a plant with yellow flowers and smooth leaves. By means of a genetic diagram, predict the ratios of the phenotypes in the offspring from these two plants assuming that the two genes are on the chromosome and are close together. Use the symbols R/r for the flower colour gene and T/t for the leaf shape gene. AO2 4 MARKS Click or tap here to enter text. 4 4.A bull with horns and with red hair was bred on several occasions with a cow with horns and white hair. Six calves were born. All calves were roan ( a mixture of red hair and white hair).Two of the offspring had horns and 4 did not. What is the genotype of the bull and the cow? Use a genetic cross to show the genotype and phenotype of the offspring. AO2 4 MARKS Click or tap here to enter text. 5. Outline the effects of mutant alleles on the phenotype in Huntington’s disease. AO1 3 MARKS Click or tap here to enter text.
