Microbiology 2124
Exam 3
April 22, 1999
David Demezas

General Instructions: Fill in the requested information including your name, social security number, class (2124) and section number (001). Answer multiple choice questions on the scantron sheet. Answer other questions in the space provided on the test sheet. Be sure that you answer the question in complete sentences. Write your name on all pages of the test.
Multiple Choice (2 pts each). Choose the most correct answer and mark the corresponding letter on your scantron sheet.

D 1. Molecular phylogeny of bacteria is based on comparative analysis of _________ sequences.
A. ribosomes
B. 23s rRNA
C. RNA polymerase
D. 16S rRNA
E. DNA polymerase

E 2. Which of the following species of phototrophic bacteria has two photosystems analogous to higher plants?
A. Green sulfur bacteria
B. sulfate reducing bacteria
C. Purple non sulfur bacteria
D. Purple sulfur bacteria
E. Cyanobacteria

D 3. Which of the following is not true about anoxygenic photosynthesis?
A. It requires anaerobic conditions.
B. ATP is formed by cyclic photophosphorylation.
C. Bacteriochlorophyll is involved in the light reactions.
D. Water is oxidized to produce electrons and oxygen is released.
E. B and D

A 4. True (A) or False (B): Methane is produced by anaerobic methanogens and oxidized by aerobic methanotrophs.

A 5. ______ oxidize ammonia to nitrite and ________ oxidize nitrite to nitrate in soil.
A. Nitrosomonas / Nitrobacter
B. Bacillus / Nitrobacter
C. Pseudomonas / Nitrosomonas
D. Nitrobacter / Nitrosomonas
E. None of the above.

B 6. Which of the following compounds would be an unlikely energy source for chemolithotrophs?
A. NH₄⁺
B. SO₄^-2
C. Fe⁺²
D. H₂
E. All of the above.

B 7. Which of the following characteristics is common to both pseudomonads and Escherichia coli?
A. They both produce endospores.
B. They are both Gram negative rods.
C. They are both enteric bacteria.
D. They both are strict anaerobes.
E. All of the above are true about pseudomonads and Escherichia coli.

B 8. Which of the following is a species of nitrogen fixing bacteria?
A. Pseudomonas
B. Azotobacter
C. Proteus
D. Chromobacterium
E. Streptococcus

E 9. Which of the following is (are) potentially pathogenic to man?
A. Escherichia coli
B. Shigella
C. Salmonella
D. Proteus
E. All of the above.

A 10. True (A) or False (B): Strains of Bacillus thuringiensis have been used to control certain plant pests such as tent caterpillar and gypsy moth.

D 11. Which of the following is not an Archaea?
A. methanogens
B. extreme halophiles
C. extreme thermophiles
D. methanotrophs
E. Thermoplasma

C 12. Extreme halophilic archaea require between _____ salt for optimal growth.
A. 0 M
B. 0.5 M
C. 2 to 4 M
D. 10 M
E. 25 M

B 13. Which of the following characteristics unifies the phylogenetic group Crenarchaeota?
A. extreme halophiles
B. hyperthermophily
C. methanotrophy
D. chemolithotrophy
E. None of the above.

D 14. ______ use a membrane associated protein, bacteriorhodopsin, to generate a proton motive force to drive ATP synthesis.
A. Pseudomonads
B. Sulfate reducing bacteria
C. Methanogens
D. Halobacterium
E. Bacillus

A 15. True (A) or False (B): Methane is generated by methanogens when they use carbon dioxide as a terminal electron acceptor in anaerobic respiration.

A 16. True (A) or False (B): Elemental sulfur can be used as either an energy source or as a terminal electron acceptor in anaerobic respiration.

A 17. Hyperthermophiles produce large amounts of ______ as an adaptation to their extreme environment.

A. 2,3 diphosphoglycerate
B. water
C. glucose
D. pyruvate
E. citrate

18-20 Matching. Match the correct description with the genus of bacteria. Only one letter matches each species.

B 21. After a virus has attached and penetrated into a host cell, no virus can be detected until the host cell is lysed. This stage of viral replication cycle is called ________.
A. penetration
B. latent period
C. budding
D. lysis
E. attachment

A 22. Which of the following human infectious diseases has been eradicated?
A. Smallpox
B. AIDS
C. Measles
D. Cholera
E. Flu

C 23. Which of the following statements about virus replication is false?
A. Virus replication involves de novo synthesis of viral proteins.
B. Viruses are obligate intracellular parasites.
C. Viruses reproduce by binary fission.
D. A and C
E. None of the above statements are false.

A 24. Which of the following is the first virus identified?
A. Tobacco Mosaic Virus
B. Human Immunodeficiency virus
C. Herpesvirus
D. Smallpox virus
E. None of the above.

E 25. Viruses can be isolated from which of the following?
A. Animals
B. Plants
C. Fungi
D. Bacteria
E. All of the above.

A 26. True (A) or False (B) Bacteriophage lambda can insert its genome into the host bacterium's genome.

A 27. True (A) or False (B) The genetic material of a retrovirus is RNA.

A 28. True (A) or False (B) The genome of some viruses consists of single stranded DNA.

A 29. True (A) or False (B) Some viruses can cause cancer.

B 30. True (A) or False (B) Viruses are larger than bacteria.

A 31. Which of the following are phototrophs?
A. algae
B. mushrooms
C. slime molds
D. protozoa
E. yeast

C 32. Crushed cell walls of diatoms (diatomaceous earth) is used to control plant pests. The cell wall is composed of ________.
A. cellulose
B. chitin
C. silica
D. xylans
E. nucleic acids

D 33. Which of the following statements about fungi is false?
A. They are heterotrophs.
B. Their cell wall is composed of chitin.
C. They do not have chlorophyll.
D. They do not contain a membrane bound nucleus.
E. They are decomposers.

B 34. Mushrooms are classified as __________.
A. Ascomycetes
B. Basidiomycetes
C. Zygomycetes
D. Oomycetes
E. Deuteromycetes

C 35. The usual mode for protozoa and slime molds to obtain food is by _____.
A. autotrophy
B. osmosis
C. phagocytosis
D. lithotrophy
E. None of the above

D 36. Which of the following groups of organisms are unicellular and lack a cell wall?
A. Fungi
B. Molds
C. Yeast
D. Protozoa
E. None of the above.

A 37. Which of the following protozoan groups causes African sleeping sickness in humans?
A. Mastigophora
B. Sarcodina
C. Ciliphora
D. Sporozoa
E. All of the above

C 38. Which of the following is an asexual spore?
A. basidiospore
B. ascospore
C. conidia
D. oospore
E. zygospore

B 39. True (A) or False (B): Sporozoa form spores as its name implies!

B 40. True (A) or False (B): All protozoa are obligate aerobes.

D 41. Which of the following characteristics would not be important for a microorganism used in an industrial process?
A. Fast growth rate
B. Genetically stable
C. Amenable to genetic manipulations
D. Must be a prokaryote
E. Must not be a plant or animal pathogen

D 42. The production of secondary metabolites occurs at or near the onset of which microbial growth phase?
A. Lag
B. Log
C. Exponential
D. Stationary
E. Death

B 43. True (A) or False (B): Secondary metabolites are essential for growth of the microorganism producing it.

C 44. Which of the following microbial products is not a primary metabolite?
A. vitamin B12
B. riboflavin
C. antibiotics
D. ethanol
E. amino acids

E 45. Important industrial products produced by microorganisms include ____.
A. the cells themselves
B. primary metabolites
C. enzymes
D. secondary metabolites
E. all of the above.

C 46. Commercial production of amino acids relies upon which of the following techniques for increasing yield of the product?
A. Obtaining mutants not subjected to feedback inhibition
B. Obtaining mutants insensitive to repression.
C. A and B
D. none of the above.

B 47. True (A) or False (B): All antibiotics are produced by fungi.

A 48. True (A) or False (B): Bioconversion is a process of transforming or modifying a chemical using bacteria to carry out the transformation.

B 49. True (A) or False (B): Viruses have no place in industrial microbiology.

B 50. Vitamin B12 is made exclusively by microorganisms. Commercially B12 is synthesized by _________.
A. Bacillus species
B. Propionibacterium species
C. Streptomyces species
D. Ashbya species
E. Rhizopus species

51. (10 pts) The 16s ribosomal RNA gene has been called a "mosaic of domains". Name and describe the three domains of the 16s rRNA gene discussed in class.
The 16s rRNA gene is composed of three domains; they are highly conserved, semi-conserved and hyper-variable domains. These domains are distributed throughout the gene. Comparison of 16s rRNA genes from many different species of bacteria revealed these domains. The highly conserved domains show very little differences between all of the compared sequences of eubacteria (Bacteria). The semiconserved sequences show some variability but are conserved among members of the same phylogenetic groups such as methanogens. The hypervariable domains show a low degree of similarity between different species examined.

52. (10 pts) Life exists at temperatures that normally denature DNA and proteins. What types of adaptations have bacteria evolved that protect (a) DNA and (b) proteins and allow extreme thermophiles to live at temperatures approaching 100oC?
DNA and proteins are denatured by high temperatures. Extreme thermophiles have evolved a number of different adaptations to these high temperatures. To protect the DNA, DNA binding proteins, which bind to DNA, are synthesized. A specific solute, 2,3-diphosphoglycerate, is produced in large amounts. This compound helps both DNA and proteins from being denatured by high temperatures. Proteins have primary structures that lead to increased stability of the secondary, tertiary and quatenary structures of proteins. Also small proteins called chaperonins are synthesized to help protect proteins.