Chapter 13 Metabolic Diversity of Microorganisms,100% CORRECT

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) The metabolic diversity of photosynthetic bacteria stems from different A) bacteriochlorophylls and pigments they contain. B) chlorophylls they can have and organic compounds they can produce. C)... light-harvesting complexes, electron donors, and organic compounds they produce. D) unrelated taxa capable of photosynthesis. 2) Whether an organism is classified as a photoheterotroph or a photoautotroph depends on its A) energy source. B) carbon source. C) oxygen requirements. D) carbon and energy sources. 3) In photosynthesis, NADH and NADPH are produced from NAD+ and NADP+ by A) oxidation reactions. B) reduction reactions. C) both oxidation and reduction reactions. D) neither oxidation nor reduction reactions. 4) Bacteriochlorophyll and chlorophyll contain ________ as a cofactor. A) iron (II) B) iron (III) C) magnesium D) manganese 5) In contrast to chlorophylls, carotenoids function A) as accessory pigments that enable absorption of energy from higher wavelengths. B) primarily as photoprotection (but they also transfer some absorbed energy into reaction centers). C) to convert reactive oxygen species into usable energy. D) to quench toxic oxygen species. 6) Proteomic analysis of a microbial community indicated an abundance of phycobiliproteins. Which phototrophic group is likely active and abundant in this community? A) cyanobacteria B) eukaryotic phototrophs C) green bacteria D) prochlorophytes 7) At some of the lowest light concentrations, ________ can still grow well due to their ________, which effectively harvest photons for energy. A) green bacteria / antenna pigments B) green bacteria / chlorosomes C) purple bacteria / antenna pigments D) purple bacteria / chlorosomes 8) Light energy passes from phycobiliproteins to reaction centers in A) cyanobacteria. B) green sulfur bacteria. C) purple bacteria. D) most photosynthetic bacteria. 9) Two separate photosystems involved in electron flow is a hallmark of A) anoxygenic phototrophs. B) green sulfur bacteria. C) oxygenic phototrophs. D) purple bacteria. 10) Intracytoplasmic membrane systems housing vesicles known as chromatophores, which function in photosynthesis, are commonly found in A) algae. B) green sulfur bacteria. C) most autotrophic organisms. D) purple phototrophic bacteria. 11) "Special pair" is the name given to the ________ in the photochemical complex of the purple bacteria. A) two bacteriochlorophyll a molecules B) two bacteriochlorophyll b molecules C) two quinones D) two reaction centers 12) What will happen to a cyanobacterium that has its photosystem II (PSII) blocked? A) Additional electron acceptors, such as NADP+, will be required to oxidize oxygen and overcome the lost PSII process. B) Anoxygenic photosynthesis only using photosystem I (PSI) could occur by using cyclic photophosphorylation and an alternative electron donor such as H2S. C) It will die from being unable to obtain energy for photosynthesis. D) Photons will generate excessive reactive oxygen species and the cyanobacterium will die as a consequence. 13) Which group of microorganisms would the Calvin cycle LEAST likely be found in? A) anoxygenic Bacteria B) chemolithotrophic Bacteria C) cyanobacteria D) hydrocarbon catabolizing Bacteria 14) The process by which electrons from the quinone pool are forced against the thermodynamic gradient to reduce NAD+ to NADH is called reverse A) proton motive force. B) reduction. C) electron transport. D) energy flow. 15) The path of electron flow in oxygenic phototrophs is referred to as the ________ scheme. A) E B) S C) Q D) Z 16) Plastocyanin is a A) membrane-bound sac found in certain bacteria. B) photosynthetic pigment found in some bacteria. C) copper-containing protein in photosystem II that donates electrons to photosystem I. D) blue-green bacterium known for its unusual photoreactive complex. 17) The Calvin cycle A) is responsible for the fixation of CO2 into cell material. B) utilizes both NAD(P)H and ATP. C) requires both ribulose bisphosphate carboxylase and phosphoribulokinase. D) uses CO2, NAD(P)H, and ATP to make biomass with ribulose bisphosphate carboxylase and phosphoribulokinase. 18) Regarding CO2 fixation mechanisms in the autotrophic green sulfur bacteria, A) Chlorobium uses the reverse citric acid cycle, and Chloroflexus uses the hydroxypropionate pathway. B) Chlorobium uses the hydroxypropionate pathway, and Chloroflexus uses the reverse citric acid cycle. C) both Chlorobium and Chloroflexus use the reverse citric acid cycle. D) both Chlorobium and Chloroflexus use the hydroxypropionate pathway. 19) In most cases, the final product of sulfur oxidation is A) hydrogen sulfide. B) elemental sulfur. C) sulfate. D) thiosulfate. 20) Identifying carboxysomes in a bacterium suggests it A) contains the reverse citric acid cycle. B) has a deficient Calvin cycle and accumulated CO2. C) is in a carboxylic acid rich environment and is storing excess quantities for potentially harsh conditions. D) will use the Calvin cycle convert the concentrated CO2 into biomass. 21) Ferrous iron (Fe2+) oxidation generally occurs in environments with A) alkaline conditions. B) high H+ concentrations. C) high oxygen content. D) little or no light present. 22) Alternative autotrophic routes to the Calvin cycle such as the reverse citric acid cycle and the hydroxypropionate pathway are unified in their requirement for A) CO2. B) coenzyme A. C) NAD(P)H. D) organic compound(s) formed. 23) The aerated upper layer of soil is likely to have ________ concentrations of H2 for aerobic H2-oxidizing Bacteria, so these bacteria likely ________. A) high / thrive in such conditions by not competing with chemoorganotrophs B) high / generate important reducing equivalents as byproducts for other microorganisms in the soil C) low / do not occur in such habitats D) low / will need a chemoorganotrophic way to grow as well 24) What metabolic advantage do cells have in storing the elemental sulfur byproduct from sulfide oxidation? A) The cells avoid producing transport energy waste to secrete the sulfur. B) The byproduct serves as an electron reserve for subsequent oxidation. C) Sulfur decreases the intracellular acidification for non-acid-tolerant sulfide oxidizers. D) The byproduct can be used for other biosynthetic pathways that use sulfur, such as Rieske Fe-S proteins. 25) A cell that lacks sulfite oxidase but can still oxidize sulfur for energy could be identified by A) adenosine phosphosulfate reductase coupled with substrate-level phosphorylation. B) electrons being transferred to cytochrome c prior to shuttling them into the electron transport chain. C) identifying an alternative quinone, flavoprotein, or cytochrome. D) quantifying the release of sulfate byproduct. 26) The only organisms that perform photosynthesis are ones that produce some form of A) chlorophyll or bacteriochlorophyll. B) carotenoids. C) phycoerythrin. D) phycocyanin. 27) Which of the following are NOT found within the photosynthetic gene cluster of Rhodobacter (a purple phototrophic bacterium)? A) genes encoding reaction center and light-harvesting photocomplexes B) genes encoding proteins involved in phycobiliprotein biosynthesis C) genes encoding proteins involved in bacteriochlorophyll biosynthesis D) genes encoding proteins involved in carotenoid biosynthesis 28) Anammox is an anaerobic process that generates energy from ________ and forms N2. A) ammonia B) ammonium C) ammonia and nitrate D) ammonia and nitrite 29) What would likely occur if an anammox bacterium was unable to use ladderane lipids? A) Ammonium rather than ammonia would be used due to ammonia toxicity to other cellular processes. B) It would require a different source for carbon assimilation. C) Rates of anammox would be considerably slower due to a lack of localized metabolism. D) Reactive nitrogen species would kill the cell. 30) Which of the following reactions is classified as a heterofermentation? A) hexose 2 lactate + 2 H+ B) HCOOH H2 + CO2 C) glucose lactate + ethanol + CO2 + H+ D) fructose 3 acetate + 3 H+ 31) Glucose fermentation by Clostridium spp. produce ATP only when acetate and butyrate are produced. Why do these organisms produce acetone and butanol after strong initial activity of generating ATP with acetate and butyrate byproducts? A) Acetate and butyrate accumulation creates a deadly acidic environment, which acetone and butanol do not. B) Acetate and butyrate are no longer needed for biosynthetic pathways. C) Acetone and butanol serve as better sources for NAD(P)+ reduction. D) Acetone and butanol production is favored for stability to store intracellular carbon sources for potential nutrient poor conditions. 32) The foul-smelling putrescine byproduct suggests activity of A) amino acid fermentation by clostridia. B) secondary fermentation. C) sulfur-oxidizing bacteria. D) syntrophic carbohydrate metabolism. 33) A bacterium that catabolizes a compound by linking ion pumps to establish a proton or sodium motive force for energy A) can circumvent substrate-level and oxidative phosphorylation. B) makes insufficient energy to grow but enough for cellular maintenance to survive. C) requires a second bacterium to cooperatively drive the gradient. D) still requires another carbon substrate to provide a carbon source. 34) Which metabolic strategy’s existence suggests rapid growth is NOT always the best strategy to survive in the environment? A) anaerobic fermentation B) disproportionation C) methylotrophy D) syntrophy 35) Obligate anaerobes can often use ________ electropositive redox couples than facultative anaerobes, and ________ metabolism is most common in this group as well. A) lower / assimilative B) lower / dissimilative C) higher / assimilative D) higher / dissimilative 36) In Bacteria, the MOST common oxidized form of nitrogen is ________ and of sulfur is ________. A) nitrate / sulfate B) nitrate / sulfite C) nitrite / sulfate D) nitrite / sulfite 37) Anaerobic fermentation often provides CO2, which can be used by ________ as an electron acceptor for energy. A) acetogens B) methanotrophs C) methanogens D) acetogens and methanogens 38) How is ATP made by an acetogen during CO2 fixation? A) Electrons from metal cofactors energize the electron transport chain and drive the proton motive force to activate ATP synthase. B) Substrate-level phosphorylation of ADP occurs when coenzyme A is removed from acetyl-CoA. C) It is made by substrate-level phosphorylation and a Na+-translocating ATPase. D) The energized CO-CH3 complex during thioesterification drives a Na+-translocating ATPase. 39) A researcher lacked the necessary equipment to measure methane production so instead monitored CO2 concentration as the unknown archaeon grew and produced methane. Why might CO2 NOT decrease but methane still increase? A) An alternative carbon source such as methanol was used. B) CO2 is not a carbon source used by methanogens. C) CO2 was used an electron donor but not as a carbon substrate. D) Methanogenic Archaea containing carboxysomes likely made measuring small losses of CO2 difficult to conclude. 40) Methanogens that use methyl-CoM for biosynthesis use ________ as a substrate. A) acetate B) carbon monoxide C) methane D) methanol 41) The serine pathway and ribulose monophosphate pathway can both be used by ________ as a way to incorporate carbon into biomass. A) acetogens B) anoxygenic hydrocarbon fermenters C) methanogens D) methylotrophs 42) What products would be expected to form during anoxic degradation of the seven-carbon compound benzoate following reduction and cleavage of the aromatic ring? A) 1 three-carbon compound and 1 four-carbon compound B) 1 three-carbon compound and 2 two-carbon compounds C) 2 three-carbon compounds and CO2 D) 3 two-carbon compounds and CO2 43) Organisms that aerobically catabolize methane use the intermediate ________ for biosynthesis and produce ________ when oxidizing the substrate for energy. A) CH2O (formaldehyde) / CO B) CH2O (formaldehyde) / CO2 C) HCOO− (formate) / CO D) HCOO− (formate) / CO2 44) Which of the following is NOT a potential reason anoxic methane-oxidizing Archaea have not also acquired the ability to reduce sulfate? A) An individual electron acceptor such as sulfate is not always present where methane is. B) Minimizing the metabolic requirements of the archaeon's genome size provides flexibility to interact with other reducing bacteria, such as nitrate reducers. C) The archaeon-bacterium relationship yields more energy from methane oxidation/sulfate reduction when performed together than separately. D) The methane-oxidizing Archaea will not easily acquire this metabolic capability from the bacterial partner 45) What metabolism would be favored when there is a lack of electron acceptors? A) anaerobic fermentation B) anoxygenic photosynthesis C) anoxic ammonia oxidation D) acetogenesis True/False Questions 1) The conversion of light into chemical energy is called photoautotrophy. 2) The light-harvesting pigments in Bacteria are classified as bacteriochlorophylls. 3) Reaction centers ONLY indirectly receive photon energy via light-harvesting molecules. 4) Chlorosomes are present in purple bacteria but absent in green sulfur and nonsulfur bacteria. 5) Carotenoids are hydrophobic accessory pigments and vary widely in the color they can absorb. 6) Each chlorophyll and bacteriochlorophyll type is distinguished by its absorption spectrum. 7) Photooxidation reactions can lead to the production of toxic forms of oxygen and the destruction of the photosynthetic apparatus. 8) The Calvin cycle provides autotrophs the ability to convert inorganic carbon into biomass and generate energy during this process. 9) A bacterium that uses CO2 as an electron source but CANNOT use it as a carbon source is considered a mixotroph. 10) Phototrophic purple bacteria such as Rhodobacter species grow ONLY by photosynthesis, using bacteriochlorophylls to harvest light. 11) Despite being called the reverse citric acid cycle, it is currently identified as the most ancient autotrophic pathway. 12) Chemolithotrophs that obtain electrons from donors such as sulfide use the same electron transport chains to obtain energy as chemoorganotrophs. 13) Photosystem I is responsible for splitting a water molecule in the first step of oxygenic electron flow. 14) RubisCO converts ribulose bisphosphate and CO2 into two molecules of 3-phosphoglyceric acid (PGA). 15) Organisms grown with CO2 as its sole carbon source must have energy in the form of ATP as well as reducing power. 16) Iron-oxidizing bacteria grow better in alkaline environments where protons are less likely to abiotically convert Fe2+ into Fe3+. 17) Some sulfur-oxidizing bacteria can simultaneously reduce nitrate, which enables them to grow anaerobically. 18) Due to a chemical equilibrium, a syntrophic relationship can be disrupted if the product from the first partner's metabolism is removed too quickly. 19) Because H2 levels in oxic environments are transient, it is likely that aerobic hydrogen bacteria shift between chemoorganotrophy and chemolithotrophy depending on levels of organic compounds and hydrogen in their habitats. 20) Some anaerobic bacteria not only use organic compounds as a carbon source but can also use them for energy as well. 21) Heterofermentation CANNOT be differentiated from homofermentation based on the compound fermented. 22) A monooxygenase can always be distinguished from a dioxygenase by incorporating only one oxygen atom from O2 into the substrate rather than both. 23) Reductive dechlorination involves chlorinated organic compounds serving as electron donors and releasing the chloride in inorganic forms. 24) Fermentation of organic compounds, such as acetate, produces NADH and ATP. 25) The acetyl-CoA pathway is a primary route for carbon source utilization. 26) When elemental sulfur is provided externally as an electron donor, the organism must attach itself to the sulfur particle because of the extreme insolubility of elemental sulfur. 27) One result of the oxidation of reduced sulfur compounds is a rise in the pH of the medium. 28) Bacteria that are capable of oxidizing both iron and sulfur usually have a strong preference for sulfur oxidation because it yields more energy. 29) Beta-oxidation exclusively removes two carbons at a time to catabolize fatty acids regardless of the carbon chain length. 30) Bacteria that degrade aromatic compounds with reductions steps rather than oxygenase activity prior to ring fission are likely to be anaerobes. Essay Questions 1) Compare and contrast the prokaryotic and eukaryotic light-gathering machinery function and spatial organization. Why do various chlorophylls show different absorption spectra? 2) What is the difference between chlorophyll and bacteriochlorophyll, and which organisms contain each? 3) Explain the Calvin cycle process that produces a full molecule of glucose and regenerates the ribulose bisphosphate molecule. 4) In what types of organisms are carboxysomes found and what advantage do they provide for a cell? 5) Describe what occurs when elemental sulfur is provided externally as an electron donor and how energy is obtained. 6) Illustrate the reaction center of a purple bacterium with the following features highlighted: antenna pigments, the special pair, protein H, protein L, protein M, quinone pool, and ATPase. Also explain the importance of proximity for these components within a reaction center. 7) Explain why it is unlikely an iron-oxidizing bacterium would thrive in a cold stream with a neutral pH. Also propose an experiment that would test whether iron-oxidizing bacteria are present in the stream. 8) Propose why it would be advantageous for a photosynthetic microorganism to have more than one type of chlorophyll or bacteriochlorophyll. 9) Under what circumstances does oxygenic photophosphorylation use non-cyclic photophosphorylation and when does it use cyclic photophosphorylation? Also describe what occurs during each process. 10) Why does an organism that is able to respire both aerobically and anaerobically preferentially undergo aerobic respiration? 11) Explain why most iron-oxidizing bacteria are obligately acidophilic, and discuss some of the environments where these organisms are found. 12) Explain why the discovery of iron-oxidizing phototrophs has important implications for both understanding the evolution of photosynthesis and explaining the large deposits of ferric iron (Fe3+) found in ancient sediments on Earth. [Show More]

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