BioSc221/325
Exam 5
Name ______________________________
Multiple choice. (1 point each) Choose the one best answer to each of the following questions.
____ Fluorescent in situ hybridization (FISH) has become a valuable tool for environmental microbiologists because
A. FISH made it possible to observe microbes in their natural environment in association with other microbes.
B. FISH made it easier to obtain pure cultures of individual microbes.
C. FISH could be used to demonstrate the diversity of microbes in an environment.
D. FISH could be used to detect rare rRNA sequences over a large area.
____ Which of the following bacterial structures do not appear "phase bright" when observed through a phase contrast
microscope?
A. sulfur granules
B. gas vacuoles
C. spores
D. chromosomes
____ An organism described as a chemolithoautotroph
A. gets energy and carbon from oxidation of organic compounds
B. gets energy from inorganic compounds and carbon from organic compounds
C. gets energy from inorganic compounds and carbon from carbon dioxide
D. gets energy from organic compounds and carbon from carbon dioxide
____ Which of the following metabolic processes uses a unique set of cofactors found only in the archaea as carbon carriers?
A. methane oxidation
B. carbon dioxide fixation
C. methanogenesis
D. methanol production
____ Sulfate reducing bacteria dominate in which of the following environments?
A. anoxic freshwater sediments
B. oxic freshwater sediments
C. anoxic marine sediments
D. oxic marine sediments
____ Microbial mat communities such as those found in the Great Sippiwisset salt marsh contain layers of phototrophs created
by a combination of which gradients?
A. oxygen, sulfur and light
B. oxygen, carbon and light
C. oxygen, carbon and sulfur
D. carbon, sulfur and light
____ Anoxygenic phototrophs can use all but which of the following compounds as a source of electrons?
A. sulfide
B. water
C. organic carbon
D. hydrogen
____ Some anoxygenic phototrophs (specifically the purple bacteria) have to use a process referred to as reverse electron flow
in order to make NADPH. The reason they have to do this is
A. even after excitation by a photon of light, the bacteriochlorophyl is not electronegative enough to reduce NADP
B. they have to get rid of extra electrons
C. sulfide is not a good reductant
D. they cannot produce PMF which is needed to reduce NADP
____ Single celled cyanobacteria are being used as model organisms to study circadian rhythms. For what process do these
organisms use circadian rhythms?
A. cell division
B. differentiation into heterocysts
C. production of toxins
D. temporal separation of photosynthesis and nitrogen fixation
____ Cyanobacteria require exposure to sunlight for photosynthesis. How do they avoid the damaging effects of UV rays?
A. They produce special pigments that absorb UV light minimizing DNA damage.
B. They produce high levels of very active DNA repair enzymes.
C. They produce heterocysts that absorb UV light minimizing DNA damage.
D. They produce toxins that kill other organisms that they can use as a protective coating.
____ Finding a high concentration of living organisms around "black smokers" is surprising because
A. there is no oxygen available
B. there is no organic carbon available
C. high levels of sulfides produced by the black smokers are toxic for most living organisms
D. the temperature is always too hot for most living organisms
____ The endosymbionts that enable Riftia to survive in the harsh environment around hydrothermal vents are found in the
A. the gills
B. the plume
C. the sheath
D. the trophosome
____ The enzyme that enables Vibrio fischeri to produce light is called
A. oxidoreductase
B. fatty acid reductase
C. luciferase
D. bug lite
____ Buchnera aphidicola is a bacterial endosymbiont of aphids. It provides the aphid with amino acids such as tryptophan.
How does B. aphidicola manage to by-pass the feedback inhibition that normally prevents overproduction of amino acids?
A. The amino acid biosynthetic genes are present on a multicopy plasmid
B. They produce a modified form of tryptophan that can be used by the aphid but does not feedback inhibit biosynthesis.
C. They no longer have the genes that repress tryptophan biosythesis.
D. They are located in specialized cells called bacteriocytes.
____ Which of the following reactions of the nitrogen cycle is catalyzed only by microbes?
A. nitrification
B. denitrification
C. nitrogen fixation
D. ammonification
____ The enzyme that catalyzes the reduction of nitrogen gas to ammonia is called
A. ammonia lyase
B. ammonia monooxygenase
C. nitrate reductase
D. nitrogenase
____ Leghomoglobin is described as a truly symbiotic enzyme because
A. it carries oxygen from the plant to the bacterium.
B. the protein component comes from the plant and the heme component comes from the bacterium.
C. the protein component comes from the bacterium and the heme component comes from the plant.
D. leghemoglobin is used to attract bacteria to the roothairs of the plant.
____ Rhizobia are attracted to the roothairs of plants by
A. bacteroids
B. leghemoglobin
C. flavonoids
D. infection threads
____ The DNA that is transferred from Agrobacterium tumefaciens to its host cell is called
A. T-DNA
B. S-DNA
C. Opine-DNA
D. Recombinant-DNA
____ Which of the following is not a problem encountered when trying to use bacteria to produce large quantities of foreign
(i.e. human) protein?
A. Inclusion bodies made up of insoluble foreign protein are often formed.
B. Human genes have introns and bacterial genes do not.
C. Foreign proteins are often toxic for the bacterium.
D. Human genes are not arranged in operons like bacterial genes.
____ Plants resistant to crop pests can be produced by introducing a gene that codes for ___ into the plant genome.
A. Clostridium botulinum toxin
B. Clostridium tetanus toxin
C. Bacillus subtilis toxin
D. Bacillus thuringiensis toxin.
____ Which of the following is not a potential drawback to genetically modified plants?
A. The insect toxin might be a human allergen.
B. The insect toxin is a threat to non-pests such as monarch butterflies.
C. Antibiotic resistance genes might escape the plant in the digestive tract and enter intestinal bacteria.
D. Genetically modified plants contain genes and naturally bred plants do not.
____ Which of the following is not a key characteristic of most industrial organisms?
A. pure culture
B. able to grow on inexpensive substrates
C. isolated directly from nature
D. genetically stable
____ Which of the following is a characteristic of a secondary metabolite?
A. essential for growth and replication
B. biosynthetic enzymes are regulated along with primary metabolites
C. usually produced via simple pathways involving only a few steps
D. sensitive to growth conditions and growth stage
____ The production phase during the growth of an industrial microorganism is referred to as the
A. trophophase
B. idiophase
C. log phase
Short answer. (1 point each)
What is one reason beer making is more complex than wine making?
What kind of microbial enzyme is of interest to the detergent industry?
What is the difference between assimilatory and dissimilatory sulfate reduction?
Bacteriochlorophyls have a wide variety of absorption spectra. What advantage does this provide?
What is one potential disadvantage of using denitrification to remove nitrate from farm runoff?
What benefit does the tube worm Riftia probably supply to its endosymbiont?
How is the filamentous cyanobacterium Anabaena capable of both oxygenic photosynthesis (an oxygen producing process) and
nitrogen fixation (a process that is inhibited by oxygen)?
Describe two main differences between oxygenic and anoxygenic photosynthesis.
Why is sulfide oxidation of mine drainage containing high sulfide ores dangerous to wildlife?
The photosynthetic machinery of phototrophs is typically associated with intracytoplasmic vesicles. Why?
Why do syntrophic bacteria require an organism such as a methanogen or a sulfate reducer for growth?
Short Essay Questions. Please answer four of the following five short essay questions (6 points each - 6 bonus points possible
for answering all 5 questions)
Your textbook describes three major types of microscopy commonly used in the microbiology laboratory. Name those three
types of microscopy, and the advantages/disadvantages of each.
Describe the pathway of electrons through the Z-scheme used in oxygenic photosynthesis.
Three types of microbe-microbe or host-microbe relationships were described in class. Name those three types of relationships
and give one example of each.
What are the primary oxidation states of nitrogen in the nitrogen cycle? Name the processes that connect them.
List six biotechnological applications of microorganisms.