BIO 304 Genetics Exam I Name_______KEY_______________________
For questions #1 through #35 below, select the best/most complete option that completes the sentence or answers the question. Using the scan sheet provided, completely fill in the appropriate circle beside the number for each question. Each of these questions is 2 points of the exam total 100 points.
1. Two genes located on a single chromosome
A. always exhibit linkage B. must be less than 50 m.u. apart C. can be more than 50 m.u. apart
D. must be transcribed from the same DNA strand E. none of these
2. In Morgan’s crosses demonstrating sex-linkage in Drosophila, crossing white-eyed males with red-eyed females (both from true-breeding strains) resulted in red-eyed F1 progeny. What phenotype(s) were observed among F2 animals? A. half white, half red B. all males white C. all males red
D. all females white E. all females red
3. During gene transfer in bacteria, the recipient cell’s genome is
A. the exogenote B. the endogenote C. entirely replaced by the donor cell genome
D. replaces the donor cell chromosome E. none of these
4. Most PKU alleles of the human phenylalanine hydroxylase gene are derived from
A. exon mutations B. intron mutations C. excess blood tyrosine
D. excess dietary phenylalanine E. mutations within the phenyalanine hydroxylase gene promoter
5. RFLP alleles
A. are Mendelian recessive markers B. are due to differences in chromosome number
C. differ in locations of restriction sites D. segregate in mitosis E. none of these
6. In a testcross, the phenotypes observed among the progeny directly reflect the
A. genotypes of the tested parent gametes B. phenotypes of the tested parent
C. genotypes of the tester parent gametes D. phenotype of the tester parent
E. progeny genotypes
7. In which of the following can we recover and observe all of the products of a single meiocyte?
A. Neurospora B. E. coli C. mouse D. Arabidopsis E. Drosophila
8. Consider gametes formed in an Indian muntjac (small deer; 2n=6), in the absence of crossingover. What is the likelihood that any two gametes receive an identical chromosome set?
A. 1/2 B. 1/6 C. 1/8 D. 1/64 E. 1/128
9. In which of the following organisms would you expect to find the lowest density of genes (e.g., number of genes per million base pairs of DNA)?
A. bacteria B. yeast C. fruit fly D. Neurospora E. human
10. In well-characterized model organisms, the number of linkage groups should
A. equal the number of genes B. equal the haploid chromosome set C. be more than three
D. equal the diploid chromosome set E. be less than ten
11. In which of the following organisms are males the heterogametic sex?
A. birds B. moths C. humans D. all of these E. none of these
12. What kind of cross produces a phenotypic ratio among the progeny of 1:1:1:1?
A. dihybrid selfed B. dihybrid testcross C. trihybrid testcross D. monohybrid testcross
E. none of these produces this ratio
13. Using a specialized transducing bacteriophage, we can
A. map genes far from the viral DNA in the host cell chromosome
B. map genes near the viral DNA within the host cell chromosome
C. map the entire host cell chromosome D. infect only special host cells E. all of these
14. How many nuclear DNA molecules are present in a human cell (2n=46) during metaphase II of meiosis?
A. 23 B. 46 C. 69 D. 92 E. none of these
15. The closer that genes lie on a bacterial chromosome,
A. the more likely they are to be co-transduced B. the less likely they are to be co-transformed
C. the less likely that they are encoded by opposite DNA strands
D. the more likely that they are in operons E. none of these is true
16. In class, we covered the basis for green/white color variegation in Mirabilis. What progeny do you predict from a cross: variegated female X green male?
A. all variegated B. all green C. half white; half green D. half variegated; half green
E. mostly green with a rare variegated plant
17. T.H. Morgan was awarded a Nobel Prize in 1933 for his contributions demonstrating
A. that genes are on chromosomes B. sex linked inheritance C. sex determination
D. genetic control of eye color E. that Drosophila is a model organism
18. A bacterial strain in which an F factor is inserted into the bacterial chromosome is called
A. an Hfr strain B. prototrophic C. male D. female E. auxotrophic
19. ____________ are cytologically visible structures seen in early meiosis I that correspond to genetic crossing over events in those meiocytes.
A. sister chromatids B. telomeres C. centromeres D. tetrads E. chiasmata
20. In bacteria, ____________ strains can grow on antibiotic-containing medium.
A. sensitive B. prototrophic C. F+ D. auxotrophic E. resistant
21. In plants, meiosis occurs within the
A. seed B. meristem C. phloem D. pollen E. endosperm
22. Individual plants of identical genotype and grown under identical environmental conditions are usually
distinguishable from each other due to
A. developmental noise B. gene interactions C. polygenic inheritance
D. growth temperature E. polymorphic differences
23. Entry of a virus into a host cell and propagation of new virus particles is
A. lysogenic infection B. lytic infection C. transformation D. transduction E. proviral induction
24. Null alleles of haplo-insufficient genes are ________________ alleles.
A. dominant B. lethal C. recessive D. enhancers E. co-dominant
25. Null alleles are
A. dominant negative alleles B. partial loss-of-function alleles C. gain-of function alleles
D. loss-of-function alleles E. lethal
26. ____________ is the situation in which multiple genes contribute to a single phenotype.
A. pleiotropism B. polygenic inheritance C. complementation
D. co-dominance E. gain-of-function
27. A female mouse is heterozygous for four unlinked genes (W/w; X/x; Y/y; Z/z and is crossed to a male that is homozygous for the recessive alleles for each gene. What proportion of progeny will exhibit the same phenotypes as the male parent?
A. 1/4 B. 1/8 C. 1/16 D. 1/32 E. 1/64
28. You discover two true-breeding strains of mice with white fur. All progeny from crosses between these two strains produces have black fur. You conclude that the genes for white fur in these strains
A. fail to complement each other B. are allelic C. are dominant
D. complement each other E. none of the above
A woman’s grandfather had galactosemia, a rare autosomal recessive inability to process galactose, leading to muscle, nerve, and kidney malfunction. The woman marries a man whose sister had galactosemia, and the couple is expecting their first child. Respond to questions #29-#31 based on this situation.
29. What is the likelihood that the child has galactosemia?
A. 1/4 B. 1/8 C. 1/12 D. 1/6 E. 1/3
30. If the couple’s first child is galactosemic, what is the likelihood that their second child will have galactosemia?
A. 1/4 B. 1/8 C. 1/12 D. 1/6 E. 1/3
31. If the couple’s first child is normal, what is the likelihood that their second child will have galactosemia
A. 1/4 B. 1/8 C. 1/12 D. 1/6 E. 1/3
Use the following human pedigree for a rare kidney disease to respond to questions #32-#34.
32. What is the mode of inheritance of this disease?
A. autosomal dominant B. autosomal recessive C. sex-linked dominant
D. sex-linked recessive E. none of these
33. If individuals 1 and 2 marry, what is the likelihood that their first child exhibits the disease?
A. 1/4 B. 1/2 C. 1/8 D. 0 E. 1
34. If the first child of individuals 1 and 2 exhibits the disease, what is the likelihood that their second child exhibits the disease?
A. 1/4 B. 1/2 C. 1/8 D. 0 E. 1
35. If a man of blood group AB marries a woman of blood group A whose father was of blood group O. To what different blood groups can the children of this couple belong?
A. any B. A, B or AB only C. AB or O only D. A or B only E. A, B or O only
************************ END of multiple-choice questions *********************************
Name_________________________
____ Recitation section _________________
For the following, provide the requested information, showing your work where possible (use the back of the page, if necessary).
In a generalized-transduction system using P1 bacteriophage, the bacterial donor strain is pur+ nad+ pdx- and the recipient straim is pur- nad- pdx+ The donor allele pur+ is initially selected after transduction and 50 pur+ transductants are tested for the nad and pdx markers, producing the following results:
Genotype Number of colonies
pur+ nad+ pdx+ 3
pur+ nad+ pdx- 10
pur+ nad- pdx+ 24
pur+ nad- pdx- 13
50
a. What is the cotransduction frequency for pur and nad? (2 pts.) 13/50 = 26%
b. What is the cotransduction frequency for pur and pdx? (2 pts.) 23/50 = 46%
c. Is nad or pdx closest to pur? (2 pts.) pdx is closest
d. Given the result in question c, there are two possibilities: nad and pdx on the same side or on opposite sides of pur. Which is it? (Hint: draw the possible orders and, for each order, draw the exchanges needed to produce the results; then determine which best agrees with observed frequencies) (4 pts.) nad and pdx are on the same side of pur
pur+ pdx- nad+ requires 4 crossovers to create pur+ nad+ pdx+ (the least frequent product)
pdx- pur+ nad+ requires 2 crossovers to create pur+ nad+ pdx+
A rice breeder obtained a triple heterozygote carrying the three recessive alleles for albino flower (al), brown awns (b), and fuzzy leaves (fu), all paired with their wild-type alleles. This plant was testcrossed, resulting in the following phenotypes among 1000 progeny plants:
124 wild-type 265 albino 16 brown 83 fuzzy
136 albino, brown, fuzzy 275 brown, fuzzy 24 albino, fuzzy 77 albino, brown
a. The triple heterozygote was created by crossing two true-breeding strains of rice. What were the genotypes of those true-breeding strains? (5 pts.)
homozygous al fu+ b+ and homozygous al+ fu b
b. Draw a map indicated the order and map distances separating these three genes. (10 pts.)
al fu b al-fu sco: 124+136 = 260/1000
_____________________________ fu-b sco: 83+77 = 160/1000
260+40 160+40 dco: 16+24 = 40/1000
1000 1000
30 mu 20 mu
c. What is the crossover interference value across this interval? (5 pts.)
1-(obs dco/exp dco) = 1-(40/60) = 0.33
Quick Reply
