BIO313 Exam(2) Practice Questions SP2024

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BIO313 Exam (2) SP2024 Practice Questions 1. Breast development in mammals is typically only seen in females and the trait is inherited on the autosomes. This is an example of a A. Y-linked trait B. X-linked trait C. sex-influenced trait D. sex-limited trait 2. The color of sunflower pollen can be orange, yellow, or white-cream. Crosses reveal that true- breeding orange is dominant to both yellow and white-cream. However, a cross between true-breeding white-cream and yellow plants produced F1 plants with orange pollen. The F2 populations of this cross resulted in a ratio of 12 orange: 3 white-cream: 1 yellow. a) What is the genotype of the orange progeny? b) What is the genotype of the white-cream progeny? c) What is the genotype of the yellow progeny? d) Draw the pathway describing the required actions and substrates. 3. In Drosophila melanogaster, short wings are caused by an allele (X s ) that is X linked and recessive to an allele for normal wings (X + ). White eyes are caused by an allele (w) that is autosomal and recessive to an allele for gray eyes (w + ). A female fly that is homozygous for normal wings and gray eyes mates with a male fly that has short wings and white eyes. The F 1 are intercrossed to produce the F 2 . What will the phenotypes and proportions of the F 2 flies be from the cross? 4. All forms of extranuclear inheritance involve _____. a) DNA carried by organelles other than the nucleus b) endosymbiotic cells carried in the cytoplasm c) gene products carried by the ooplasm d) transmission from the maternal parent to all offspring e) transmission of information via the cytoplasm 5. With which of the following would hemizygosity most likely be associated? A) codominance B) incomplete dominance C) trihybrid crosses D) X-linked inheritance E) sex-limited inheritance 6. In foxes, two alleles of a single gene, P and p , may result in lethality ( PP ), platinum coat ( Pp ), or silver coat ( pp ). What ratio is obtained when platinum foxes are interbred? A) 1/2 platinum; 1/2 silver B) 1/3 platinum; 2/3 silver C) 3/4 platinum; 1/4 silver

D) 2/3 platinum; 1/3 silver E) 1/4 platinum; 3/4 silver 7. Bill and Betty have two children with Down syndrome. Bill’s brother has Down syndrome and his sister has two children with Down syndrome. On the basis of these observations, which of the following statements is most likely correct? A) Bill has 47 chromosomes B) Betty has 47 chromosomes C) Bill and Betty’s children each have 47 chromosomes D) Bill’s sister has 45 chromosome E) Betty has 45 chromosomes 8. Answer: 9. For the follow pedigree state whether the affected condition is inherited by autosomal dominant, autosomal recessive, X-linked recessive or X-linked dominant. 10. If an affected male has all affected daughters but no affected sons, the trait is likely to be an A. X-linked dominant trait B. autosomal recessive trait C. autosomal dominant trait D. X-linked recessive trait 11. While working in a genetics lab over the summer, you isolated a true-breeding strain of wingless Drosophila . After sharing your results with your mentor, you learn that six other true-breeding strains of Drosophila with the same mutant phenotype have been isolated independently in your lab. Your mentor asks you to determine if the mutants belong to the same complementation group. What is true about flies that belong to the same complementation group? A) They all have the same mutation in the same wing- development gene. All flies in a complementation group have identical DNA sequences for this gene.

B) They all have some mutation in the same wing-development gene. Each strain may have a different mutation, but the same gene is mutated in all strains in a complementation group. C) They all have some mutation in some wing-development gene. Each strain may have a different mutation in a different gene, but all strains within a complementation group have the same phenotype. D) None of the above is correct 12. Mendelian ratios are modified in crosses involving autotetraploids. In wheat, the brown seed trait is dominant to white seeds. A true-breeding brown seed plant (genotype WWWW) is crossed to a true-breeding white seed plant (genotype wwww). If F1 progeny (genotype WWww) are crossed to true-breeding white seed plants (wwww), what proportion of the F2 progeny do you expect to have white seeds? Assume that a single dominant W allele is sufficient to produce brown seeds, and that synapsis between any two chromosomes carrying a W or w allele is equally likely. A) 1/36 B) 1/18 C) 1/6 D) 1/3 E) 1/2 13. In chick, feather colors are produced by the interactions between two different loci (A and B). These two loci are not sex-linked and independently assorted. When a heterozygous male is crossed with a heterozygous female, F 2 progeny are produced in the following ratio of their genotypes and phenotypes: A_B_: (yellow); 9/16 A_bb: (green); 3/16 aaB_:(white); 3/16 aabb:(white); 1/16 Which the following gene interaction could be used to explain the genotypic and phenotypic ratios of the F 2 progeny? A) B) C) D) 14. A boy with Klinefelter syndrome (47,XXY) is born to a mother who is phenotypically normal and a father who has the X- linked skin condition called anhidrotic ectodermal dysplasia. The mother’s skin is completely normal with no signs of the skin abnormality. In contrast, her son has patches of normal skin and patches of abnormal skin. A) The father must have contributed the abnormal X-linked gene. B) Both parents must have contributed the abnormal X-linked gene. C) The mother must have contributed the abnormal X-linked gene.

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D) Cannot be determined 15. The following diagram represents two nonhomologous chromosomes where “*” represent the centromere: AB*CDEFG RS*TUVWX What type of chromosome mutation would produce the following chromosomes? AB*CD RS*TUVWXEFG A) paracentic inversion B) duplication C) non-reciprocal translocation D) pericentric inversion E) reciprocal translocation 16. 17. On the basis of this pedigree of inheritance for Nance-Horan syndrome, what is the probability of couple of II-1 and II-2 to have another child with Nance-Horan syndrome? A chromosome with genetic markers A, B, C, D, E, and F is shown below: A B centromere C D E F ---------------------O--------------------------------------------------- Another chromosome is found to contain a b centromere e d c f ---------------------O--------------------------------------------------- If the two chromosomes are paired during meiosis, a single crossover take places between D and E. How would the expected recombinant chromosomes look like?

18. Species I is diploid (2n=4) with chromosomes aabb; related species II is diploid (2n=6) with chromosomes ccddee. Give the chromosomes (all possible situations) that would be found in individuals with allotetrapolyploidy including species I and II. Answer: 18a) Allotetrapolyploid : ______________________________________ 18b) Allotetrapolyploid: _________________________________________ 18c) Allotetrapolyploid: _________________________________________ 19. Wild-type bacteria can grow on minimal medium. Four mutants that cannot grow on minimal medium but can grow on minimal medium supplemented with the nutrient “C” are isolated. It is suspected that metabolites A, B, C, and D are in the biochemical pathway for synthesis of C, so each mutant is tested for the ability to grow on minimal medium supplemented with these metabolites. Mutant (1) can grow on minimal medium with A, but not with B or D. Mutant (2) is unable to grow on minimal medium supplemented with A, B, or D. Mutant (3) is able to grow on minimal medium supplemented with B, or A, but not D. Mutant (4) can grow on minimal medium supplemented with A, B, or D. Use this information to determine the order of metabolites A, B, and D in the C biosynthetic pathway, and indicate which step in the pathway is defective in each of the bacterial mutants. 20. In the accompanying pedigree of inheritance, determine the mode of transmission. A) Autosomal Rescessive B) Autosomale Dominant C) X-linked Recessive D) X-linked Dominant E) Y-linked 21. Duchenne muscular dystrophy is caused by a recessive X-linked allele. A man with this disorder _____. a) could have inherited it from either parent b) must have inherited it from his mother c) must have inherited it from both parents d) can pass it along to all of his children e) can pass it along to only his sons 22. A color-blind woman with Turner syndrome (XO) has a father who is color blind.

Given that the gene for the color-blind condition is recessive and X-linked, provide a likely explanation for the origin of the color-blind and cytogenetic conditions in the woman. a) woman inherited an X rg chromosome from the father b) Nondisjunction in the female (either at meiosis I or II) c) Turner syndrome condition is produced by the fertilization of the X rg -bearing sperm d) a and b e) a, b and c 23. Which of the following is a feature of X-linked dominant inheritance? A) parental consanguinity B) male to male transmission C) transmission only by females D) transmitted by males only to females 24. From the provided pedigree below, it shows the inheritance of a rare trait in humans. What is the probability that the individual shown by the “?” will not be affected by this trait? (X-linked recessive) A) 1/2 B) 1/4 C) 3/4 D) 1 E) 0 25. Many of the color varieties of summer squash are determined by several interacting loci: AA or Aa gives white, aaBB or aaBb gives yellow, and aabb produces green. Assume that two fully heterozygous plants are crossed. Give the phenotypes (with frequencies) of the offspring. A) 12 (white):3 (yellow):1 (green) B) 9 (white):3 (yellow):4 (green) C) 9 (white):6 (yellow):1 (green) 26. Which mode of chromosomal rearrangement with crossover would generate dicentric chromosome in cells? a) paracentic inversion b) duplication c) non-reciprocal translocation d) preicentric inversion e) reciprocal translocation

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BIO313 Exam(2) Practice Questions SP2024

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