AP Biology Genetics Practice Alternative Modes of Inheritance

Transcription

1 AP Biology Genetics Practice Alternative Modes of Inheritance Name: Blk: Please put all answers on a separate sheet of paper and SHOW ALL WORK! 1. In snapdragons red flower color (R) is incompletely dominant to white flower color (W) and the heterozygote has pink flowers. Green leaves (G) are dominant to purple leaves (g). A pink flowered, purple leafed snapdragon is crossed with a pink flowered snapdragon heterozygous for leaf color. If the two loci are not linked, what proportion of the progeny should be pink flowered, purple leaved plants? 2. In some plants, a true breeding red flowered strain gives all pink flowers when crossed with a white flowered strain: RR (red) x rr (white) à Rr (pink). If flower position (axial or terminal) is inherited as it is in peas, what will be the ratios of genotypes and phenotypes of the F1 generation resulting from the following cross: axial-red (true breeding) x terminal white? What will be the ratios in the F2 generation? 3. There is a rare genetic trait called sickle cell anemia which is due to an incompletely dominant gene. Persons who suffer this genetic disease have misshaped blood cells, suffer severe pain and frequently die prematurely. However, these symptoms only occur when the person has two sickle cell genes. Heterozygous individuals usually have no symptoms since the normal gene causes production of enough normal hemoglobin, and of course, persons with two normal genes are asymptomatic as well. If two people marry who are heterozygous for the sickle cell trait, what are the chances that any of their children will have sickle cell anemia? How many will be carriers? Now many will be normal? 4. Roan is the name for a peculiar color in cows and horses. It is a mixture of red and white hairs, demonstrating co-dominance. When a red cow is mated to a white bull, what will be the genotypic and phenotypic ratios to expect? What would be the outcome for the F 2 generation genotypically and phenotypically? 5. Radish roots may be long, round or oval. A farmer plants a crop of radishes which all came from seeds of the same two parents. When the crop was harvested, 2023 long radishes were produced, 1997 were round ones, and 4011 were oval. What were the genotypes of the parents? Test your prediction using Chi Square. Degrees of p= 99% 95% 80% 50% 20% 5% 1% Freedom Look at the cross below. The bottom 4 are all white, while still having the genes for a brown or black coat. How can this be explained?

2 Blood Types representing Multiple Alleles and Co-dominance Blood Type (Phenotype) Genotype Can donate blood to: Can receive blood from: O OO A,B,AB and O (universal donor) O AB AB AB A,B,AB and O (universal receiver) A AA or AO AB, A O,A B BB or BO AB,B O,B 7. The probability that a mother with blood type O and a father with genotype i B i would have a child with blood type O is. 8. The probability that a father with genotype ii and a mother with blood type AB would have a son with blood type B is. 9. In a maternity ward, four babies become accidentally mixed up. The ABO blood types of the four babies are known to be: Baby Jane is O, Baby John is A, Baby Christopher is B, and Baby Robin is AB. The ABO types of the four sets of parents are determined as such: The Andersons are AB and O, the Browns are A and O, the Christiansons are A and AB, and the Dietrichs are O and O. Indicate which baby belongs to each set of parents. 10. Color pattern in a species of duck is determined by one gene with three alleles. Alleles H and I are co-dominant, and allele i is recessive to both. How many phenotypes are possible in a flock of ducks that contains all the possible combinations of these three alleles? 11. In rabbits a grey coat color is produced by the dominant allele C. The C ch allele produces a silver grey coat color when present in the homozygous condition called chinchilla. When C ch is present with a recessive gene, a light silver grey color is produced. The allele C h produces a white color with black extremities called Himalayan. An allele C a is recessive to all genes and results in the albino (non-pigmented condition). The dominance hierarchy is: C > C ch > C h > C a. a. Indicate the genotypes and phenotypes of the F1 generation from the mating of a heterozygous Himalayan coat rabbit with an albino coat rabbit. b. The mating of a full colour rabbit with a light grey rabbit produces two full color offspring, one light grey offspring, and one albino offspring. Indicate the genotypes of the parents. 12. Plutonian Tickle-bellies have a sex determination system just like mammals. Hairy Snout is a holandric trait (carried on the Y chromosome). Rocco, a handsome male Tickle-belly, has lovely orange hair on his snout. He and his mate, Orggy, have six offspring, three boys and three girls. Please answer the following questions about this family. a. How many of Rocco s and Orggy s offspring have hairy snouts? Can you predict which ones? b. Their eldest son, Bob, marries and has a son. What is the chance that Bob s son will also have a hairy snout? c. Joco, Rocco s and Orggy s youngest daughter, marries a male who has a smooth, hairless purple snout. She has eight offspring, each one lovelier than the last, and all boys. What percentage of these offspring do you expect to have hairy snouts? Explain. 13. Earl has normal color vision, while his wife Erma is colorblind.. Colorblindness is an X-linked trait, and the normal allele is dominant to the colorblindness allele. If they have a large family, in what ways should the colorblindness trait affect their children? 14. Ethan is colorblind. His wife, Edna, is homozygous for the normal color vision allele. If they have eight children, how man of them would you expect to be colorblind? Using Punnett s squares, derive and compare the genotypic and phenotypic ratios expected for the offspring of this marriage and those expected for the offspring of the marriage described in III.3.

3 15. Marian s father is colorblind, as is her maternal grandfather (her mother s father). Marian herself has normal color vision. Marian and her husband, Martin, who is also colorblind, have just had their first child, a son they have named Mickey. Please answer the following questions about this small family. a. What is the probability that this child will be colorblind? b. Three sources of the colorblindness allele are mentioned in this family. If Mickey is colorblind, from which of these three men (Marian s grandfather, Marian s father, or Martin) did he inherit the allele? c. Using proper pedigree format, diagram the available information about the four generations of this family described, assuming that Mickey is colorblind. d. If Martin were not colorblind, how would this affect the prediction about Mickey? 16. In fruit flies (Drosophila), one eye color gene is X-linked, with a recessive white allele and a dominant red allele. If whiteeyed female flies are bred to red-eyed male flies, describe the expected offspring (assume all parental flies are true-breeding). What results do you expect if you do the reciprocal cross (reverse the phenotypes of the parent flies)? 17. In cats, there is a coat color gene located on the X chromosome. This gene is a different gene from the black/siamese gene discussed in earlier problems. This gene has two alleles orange and black. A heterozygous cat has tortoiseshell color (a splotchy mixture of orange and black). Predict the genotypic and phenotypic frequencies among the offspring of the following crosses. Pay careful attention to the genders of the offspring. a. Black female X Orange male b. Orange female X Black male c. Tortoiseshell female X Black male d. Tortoiseshell female X Orange male Pedigrees 18. Determine the most likely mode of inheritance of the indicated diseases in each of the following pedigrees and answer the questions that apply in each. Hypercholesterolemia a. What is the pattern of inheritance for hypercholesterolemia? b. What is the genotype of I1? c. What is the genotype of I2? d. What is the genotype of II2? e. What is the genotype of III3? Hunters Syndrome a. What is the pattern of inheritance for Hunters Syndrome? b. What is the genotype of I1? c. What is the genotype of I2? d. What is the genotype of II2? e. What is the genotype of II6? f. What is the genotype of III4? Alkaptonuria a. What is the pattern of inheritance for Alkaptonuria? b. What is the genotype of I3? c. What is the genotype of II3? d. What is the genotype of II4? e. What is the genotype of III1?

4 19. The following pedigree traces the inheritance of two independently assorting genes in a family. A dot represents the occurrence of an extra finger, a condition known as polydactyly. A shaded symbol represents the occurrence of an eye disease, red green color blindness. None of the individuals have BOTH conditions. a. What is the pattern of inheritance for an extra finger? b. What is the pattern of inheritance for the eye disease? c. What is the genotype of I1 (mother)? d. What is the genotype of I2 (father)? 20. Using the pedigree in the image, what type of inheritance pattern is most likely? 21. Using the pedigree in the image, what type of inheritance pattern is most likely? 22. Using the pedigree in the image, what type of inheritance pattern is most likely?

5 23. Using the pedigree in the image, what type of inheritance pattern is most likely? 24. The pedigree below traces the inheritance of alkaptonuria, a biochemical disorder. Affected individuals indicated here by the filled-in circles and squares, are unable to break down a substance called alkapton, which colors urine and stains body tissue. Does alkaptnuria appear to be caused by a dominant or recessive allele? Fill in the genotypes of the individuals whose genotypes you know. What genotypes are possible for each of the other individuals?