Tut 13 - Genetic Basis for Variation (Student)

St Andrew’s Junior College Genetics & Inheritance 2022 H1 Biology 1 Full Name: Civics group: 21S Index no.: Date: Core Idea 2: Genetics and Inheritance Dihybrid cross & Test Cross Tutorial 13 QUESTION 1 A homozygous white -flowered, long -stemmed tobacco plant, Nicotiana affinis , was crossed with homozygous pink flo wered, short-stemmed plant. The alleles for white flower and long stem are dominant to those for pink flower and short stem. The above cross gave rise to the F1 generation. The F1 plants were selfed to produce the F2 generation. Using suitable symbols, co nstruct a genetic diagram to illustrate the outcome of the above crosses. ………………………………………………………………………………………………..[6]

St Andrew’s Junior College Genetics & Inheritance 2022 H1 Biology 2 QUESTION 2 In rumbunnies, facial warts (W) is dominant to smooth face (w) and freckled face (F) is dominant to freckle-less face (f). Rumbunnies that are heterozygous for both facial warts and freckles were crossed with smooth-faced and freckle-less rumbunnies. The resultant offspring were as follows: Phenotype No. of rumbunnies Wild phenotype (facial warts, facial freckles) 45 Facial warts, freckle-less 48 Smooth face, freckle-less face 46 Smooth face, Facial freckles 51 (a) Draw a genetic diagram to show the cross described. ………………………………………………………………………………………………..[5]

St Andrew’s Junior College Genetics & Inheritance 2022 H1 Biology 3 (b) If you are given a Rumbunny with Facial Warts and Facial Freckles, explain how you would derive its actual genotype. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………..[5] [Total: 10]

St Andrew’s Junior College Genetics & Inheritance 2022 H1 Biology 4 QUESTION 3 Fruit flies ( Drosophila melanogaster) have been used extensively in investigation of inheritance. They are particularly suited to study because of their short life cycle and many different mutant forms. In one investigation, red -eyed females with grey bodies were crossed with brown -eyed males with black bodies. All the F1 generation had red eyes and black bodies. When these F1 flies were crossed, the following offspring were produced: Phenotype No. of flies Red-eyed, black-bodied 110 Red-eyed, grey-bodied 39 Brown-eyed, black-bodied 37 Brown-eyed, grey-bodied 13 (a) State the dominant characters for eye color and body color. ………………………………………………………………………………………………..[1] (b) State the genotypes of the parent flies, using suitable symbols. ………………………………………………………………………………………………….. ………………………………………………………………………………………………..[3] (c)