Licking Heights Local School District



You are attempting to determine what inheritance pattern eye color follows in Drosophila. It is known that wild-type (red) eyes (w+) are dominant to white (w). Work the following punnett squares to predict whether this trait follows a sex-linked or autosomal pattern of inheritance. Autosomal RecessiveSex-linked RecessivePYou begin by crossing a white-eyed female with a true-breeding red-eyed male. F1280035-2806700073152036957000Expected Phenotypic Ratio:Expected Phenotypic Ratio:F1 offspring are crossed to produce the F2 generation.F2280035-2806700073152036957000Expected Phenotypic Ratio:Expected Phenotypic Ratio:You perform the above crosses and observe the following phenotypic outcomes amongst the offspring that are produced:Wild-Type FemaleWhite Female White MaleWild-Type MaleF124602900F2120131137148What conclusions can be drawn from the above data? Explain how the data support your conclusions.A new species of fly was discovered on an island in the South Pacific. Several different crosses were performed, each using 100 females and 100 males. The phenotypes of the parents and offspring were recorded.CROSS I: True-breeding bronze-eyed males were crossed with true-breeding red-eyed females. All of the F1 offspring had bronze eyes. F1 flies were crossed, and the data for the resulting F2 flies are given in the table below.F2 PhenotypeMaleFemaleBronze eyes3,7203,800Red eyes1,2601,320CROSS II: True-breeding normal-winged males were crossed with true-breeding stunted-winged females. All the F1 offspring had stunted wings. F1 flies were crossed, and the data for the resulting F2 flies are given in the table below.F2 PhenotypeMaleFemaleNormal wings1,1601,320Stunted wings3,6003,820CROSS III: True-breeding bronze-eyed, stunted-winged males were crossed with true-breeding red-eyed, normal-winged females. All the F1offspring had bronze eyes and stunted wings. The F1 flies were crossed with true-breeding red-eyed, normal-winged flies, and the F2 results are shown in the table below. F2 PhenotypeMaleFemaleBronze eyes, stunted wings2,3602,220Bronze eyes, normal wings220300Red eyes, stunted wings260220Red eyes, normal wings2,2402,180What conclusions can be drawn from cross I and cross II? Explain how the data support your conclusions for each cross.What conclusions can be drawn from cross III? Explain how the data support your conclusions for this cross.For each of the following pedigrees, determine whether the trait is following an autosomal or sex-linked inheritance pattern and whether the trait being tracked is dominant or recessive. Justify your classification with evidence and identify the genotype(s) of each individual.PedigreeInheritance PatternEvidence ................
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