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 becauseA. 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 granulesB. gas vacuolesC. sporesD. chromosomes____ An organism described as a chemolithoautotroph A. gets energy and carbon from oxidation of organic compoundsB. gets energy from inorganic compounds and carbon from organic compoundsC. gets energy from inorganic compounds and carbon from carbon dioxideD. 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 oxidationB. carbon dioxide fixationC. methanogenesisD. methanol production____ Sulfate reducing bacteria dominate in which of the following environments?A. anoxic freshwater sedimentsB. oxic freshwater sedimentsC. anoxic marine sedimentsD. 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 lightB. oxygen, carbon and lightC. oxygen, carbon and sulfurD. carbon, sulfur and light____ Anoxygenic phototrophs can use all but which of the following compounds as a source of electrons?A. sulfideB. waterC. organic carbonD. 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 isA. even after excitation by a photon of light, the bacteriochlorophyl is not electronegative enough to reduce NADPB. they have to get rid of extra electronsC. sulfide is not a good reductantD. 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 divisionB. differentiation into heterocystsC. production of toxinsD. 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 becauseA. there is no oxygen availableB. there is no organic carbon availableC. high levels of sulfides produced by the black smokers are toxic for most living organismsD. 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 theA. the gillsB. the plumeC. the sheathD. the trophosome____ The enzyme that enables Vibrio fischeri to produce light is calledA. oxidoreductaseB. fatty acid reductaseC. luciferaseD. 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 plasmidB. 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. nitrificationB. denitrificationC. nitrogen fixationD. ammonification____ The enzyme that catalyzes the reduction of nitrogen gas to ammonia is calledA. ammonia lyaseB. ammonia monooxygenaseC. nitrate reductaseD. nitrogenase____ Leghomoglobin is described as a truly symbiotic enzyme becauseA. 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. bacteroidsB. leghemoglobinC. flavonoidsD. infection threads____ The DNA that is transferred from Agrobacterium tumefaciens to its host cell is calledA. T-DNAB. S-DNAC. Opine-DNAD. 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 toxinB. Clostridium tetanus toxinC. Bacillus subtilis toxinD. 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 cultureB. able to grow on inexpensive substratesC. isolated directly from natureD. genetically stable____ Which of the following is a characteristic of a secondary metabolite?A.