1. Why would soil and water be added to a compost pile? Without adding soil and water, no decomposition of the material can take place. The material would simply sit there. Soil spreads out the material in the pile. If the material is too close together, natural aeration cannot occuWe also discuss several other topics like purdue me 365
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r and decomposition stops. Water is the medium that photosynthetic organisms use to break down the organic materials in the compost pile. The organisms in the soil, along with the moisture from the water, would facilitate the natural decomposition of the material in the compost pile. 2. Which of the following soil organisms play a major role in decomposing plant matter? bacteria AND fungi protozoa AND viruses viruses AND fungi fungi AND protozoa bacteria AND viruses 3. Lichens may be an association of protozoa and bacteria. algae and fungus. virus and algae. several different fungi. 4. Why is it not surprising that AIDS patients frequently suffer a viralinduced tumor? HIV genomes integrate into the host cell chromosome. This integration might result in loss of control of the cell cycle (also known as cancer). The immune system's CD4+ T cells are directly responsible for elimination of tumor cells. HIV attacks them and eliminates them, making a person more susceptible to cancer. The therapies for HIV are highly mutagenic, which may lead to cancerous states in people taking the drug regimen. Products of an active HIV infection are highly mutagenicso, as a person's illness progresses, these mutagenic compounds build up and induce a cancerous state. 5. Haustoria are specialized hyphae used by parasitic fungi. are a form of parasitic protozoan. refers to the reproductive structure formed by slime molds. are the reproductive form of protozoans. 6. If a compost pile is turned frequently and other conditions are adequate for aerobic digestion, the composting can be completed in 1 month. six weeks. 1 day. six months. 7. Gardeners sometimes plant clover between productive growing seasons. Why would this practice be beneficial? Clover is a unique plant that is capable of atmospheric nitrogenfixation (pulling nitrogen directly out of the air and turning it into ammonia or amino acids). This directly provides nitrogen compounds for the soil for subsequent seasons of other plants' growth.Clover is consumed by a number of animals. This would encourage the animals to feed/graze on the areas, leaving behind nitrogenrich manure that would act as a natural fertilizer for subsequent seasons of other plants' growth. The beneficial effect is more for water retention and elimination of soil erosion in between growing seasons. It has nothing to do with nitrogen compounds in the soil. Several types of nitrogenfixing bacteria form a symbiotic relationship with the roots of clover. This would increase the amount of nitrogen in the soil available for subsequent seasons of other plants' growth. 8. Would you expect the number of virions to be the same if you measured them by the plaque assay or by counting using the electron microscope? Why? Nothe plaque assay only measures viable virus particles, while the electron microscope cannot distinguish between defective and viable virus. Yesonly fully functioning viruses will be released from a host cell, so the quantified number of virus particles in a plaque assay should be identical to the number of free virus particles counted by electron microscopy. Yesboth methods measure the total number of virus particles in a solution. Noyou cannot count virus particles by using a plaque assay. You can only get a relative difference in quantity from one preparation of virus particles to another with this method. 9. Streptomyces are typically found in the air. may produce antivirals. will swarm together to form fruiting bodies. may produce antibiotics. 10. Mycorrhizae increase the absorptive ability of roots AND are used in the production of wine, beer, and bread. are vital for the survival of lichens AND are vital for the survival of many plants. are used in the production of wine, beer, and bread AND are vital for the survival of lichens. are vital for the survival of many plants AND are used in the production of wine, beer, and bread. are vital for the survival of many plants AND increase the absorptive ability of roots. 11. Why are viroids resistant to nucleases? Nucleases will only digest DNA, not RNAso viroids are protected. Viroids have only been identified in plants. Plant nucleases cannot digest RNA. Having a circular RNA "genome," they are resistant to most exonucleases (that digest the free ends of RNA or DNA). Having a circular RNA "genome," with no protein shell, they are resistant to the protein degrading activities of nucleases. 12. You add an unknown phage to a mixture of F+ and F cells of E. coli and plate out the bacteria. The bacterial colonies that grow are all F. How can you explain this phenomenon? The phage bound to a receptor on the sex pilus, and therefore only infected the F+ cells (leaving the F cells alone). The phage integrated (lysogenized) the F cells, giving them a selective advantage over the F+cells. The phage bound to a receptor on the F cells, leaving only them alive and allowing the F+cells to die off. F+cells are uniquely susceptible to phage attack for unknown reasons.13. Azotobacter have a very low respiratory rate. are the chief suppliers of fixed nitrogen in grasslands. are methanogens. form symbiotic associations with algae. are the chief suppliers of fixed nitrogen in grasslands AND form symbiotic associations with algae. 14. Fungi are important because of their ability to help many plants grow. cause disease in plants. make certain foods and beverages. spoil food. All of the above. 15. Which of the following cannot be used in composting? nutrientpoor potting soil vegetable peelings grass clippings meats and fats 16. The bacteria cultured from a soil sample typically represents all the metabolically inactive bacteria. a very small number of bacteria present in that sample. all the bacteria present in that sample. all the metabolically active bacteria. 17. Why do animal viruses have envelopes and phages rarely do? Phages acquire an outer surrounding that is a part of the cell wall of the bacterium they were created in, rather than an outer surrounding of plasma membrane. Animal viruses build the envelope inside of the target cell as they are being replicated, but before the cell breaks open and releases them into the extracellular environment. The envelope is a remnant of this building process. Animal viruses will often utilize the envelope in order to fuse with the plasma membrane of a new target cell, gaining entry into the cytoplasm. Since bacteria don't have cell membranes, the bacterial viruses (phages) don't pick them up when they leave the target cells. 18. Why is it virtually impossible to stamp out a disease caused by a zoonotic virus? Many zoonotic viruses may be able to reside in more than one host organism, complicating control measures. Many viruses transmitted in this manner may utilize more than one vector organism. Many vector organisms have multiple stages of their life cycle that can carry a zoonotic virus, which complicates controlling the vectorborne transmission. All of the above are correct. You'd have to drive the vector organism extinct to do so. 19. Effective treatment of wastewater/sewage is reflected in a(n) higher BOD. unchanging BOD. lower BOD. increase in sulfur. 20. An antibiotic is added to a culture of E. coli, resulting in death of the cells. Bacteriophage are then added. Would the phage replicate in the E. colicells? Why or why not?No, because the virus would depend too much on having the active machinery of a living cell for its replication. Yes, because viruses are capable of reanimating dead cells to force them to produce more virus particles. No, because entry of the virus into the target cell is dependent on the cell being alive to conduct endocytosis of the virus. Yes, because the machinery inside the cells is most likely still active, even though the cells are no longer living. The virus could use that machinery to replicate new virus particles. 21. Algae are important environmentally as local flora. local contaminants. major producers of oxygen. major producers of carbon dioxide. 22. Fungal spores are a major cause of asthma. food spoilage. fermentation. anaerobic disease. 23. The activated sludge process is meant to convert inorganic to organic matter. is meant to increase the BOD. is used during secondary treatment of sewage. removes large objects from the sewage. is meant to convert inorganic to organic matter AND is meant to increase the BOD. 24. Why would all protozoa be expected to require large amounts of water in their habitats? Without being in water, they would quickly dehydrate (due to their small size) and die. They require water to help them during photosynthesis by providing an electron source. None of the statements is correct. They require water to move around in to seek food particles. Without water, they would be unable to move at all. 25. Truffles are a mushroom. are endomycorrhizas AND form a sheath around a root of an appropriate tree. are a lichen. form a sheath around a root of an appropriate tree. are endomycorrhizas. 26. Why would it be more difficult to treat diseases in humans caused by members of the Eukarya than diseases caused by the Bacteria? Multicellular organisms always have their own immune systems for protection so any treatment we develop needs to overcome this builtin protection mechanism in such organisms. Eukaryotic microbes use many of the same enzymes and systems as humans so we lose the ability to target certain molecules that might be present ONLY in the cell type we want to eliminate. Since bacteria are so much simpler (being singlecelled), they are naturally easier to kill off than multicellular eukaryotic microbes.Eukaryotic microbes (unlike prokaryotes) often secrete compounds that breakdown and eliminate drugs used against them. This makes them much harder to effectively eliminate than bacteria. 27. Dimorphic fungi are strictly hyphae AND are often associated with disease in humans. may grow as mycelia or yeast AND are mushrooms. may grow as mycelia or yeast AND are often associated with disease in humans. are often associated with disease in humans AND are mushrooms. 28. The terms yeast, mold, and mushrooms refers to fungal reproduction. parasites. morphology. nutrition. 29. Explain why HIV becomes resistant so quickly when a single drug is used therapeutically. The virus is an RNA genome virusby using host RNA polymerase to directly copy the genome to make more virus particles, there's no proofreading capability. This leads to a high rate of mutation of the viral genome and increased chance for drug resistance. HIV is constantly changing its genetic structure by swapping genetic elements with other virus strains. This leads to a high rate of mutation of the viral genome and increased chance for drug resistance. HIV uses reverse transcriptase to make a cDNA version of its RNA genome. This polymerase is "'sloppy," with a high rate of error and lack of a proofreading capability. This leads to a high rate of mutation of the viral genome and increased chance for drug resistance. HIV synthesizes a protein enzyme that directly cleaves antiHIV drugs, giving it a characteristically high rate of resistance to a single drug type. 30. A mutation in E. coli results in the loss of both restriction endonucleases and modification enzymes. Would you expect any difference in the frequency of gene transfer via transduction FROM Salmonella INTO this E. coli strain? Yesthe loss of the modification enzymes would leave the recipient E. coli unable to tag its own DNA as "self," leaving the viral DNA untagged and recognizable as "foreign," and targeted for destruction. This would lead to higher rates of successful transduction. Notransduction efficiency isn't affected by either restriction endonucleases or modification enzymes, so there'd be no effect on the overall rate. Nosince the Salmonella strain is normal, the rate of production of transducing virus particles would still be the same, resulting in the same frequency of gene transfer. Yesthe loss of the restriction endonucleases would leave the recipient E. coli unable to break down "invading"' viral DNA from the transducing phage. This would lead to higher rates of successful transduction. Yesthe loss of the restriction endonucleases would leave the recipient E. coli unable to break down "invading" viral DNA from the transducing phage, AND the loss of the modification enzymes would leave the recipient E. coli unable to tag its own DNA as "self," leaving the viral DNA untagged and recognizable as "foreign," and targeted for destruction. Together, these would lead to higher rates of successful transduction. 31. The problem(s) with using sludge as a fertilizer is/are the stimulatory effect it has on methane production AND presence of pathogenic organisms and viruses.inhibitory effect it has on plant growth AND stimulatory effect it has on methane production. presence of heavy metals and similar pollutants AND inhibitory effect it has on plant growth. presence of pathogenic organisms and viruses AND inhibitory effect it has on plant growth. presence of heavy metals and similar pollutants AND presence of pathogenic organisms and viruses. 32. Which of the following statements about landfills is false? Degradation of wastes is rapid and inexpensive. The excavated site has a plastic liner to prevent wastes from leaching into groundwater. Dangerous levels of methane gas can accumulate. Recycling greatly reduces the amount of wastes sent to landfills. 33. Bioaugmentation only enhances the growth, onsite, of the resident population of microbes. is typically done offsite. usually utilizes genetically engineered bacteria. adds specific microorganisms to the polluted site. 34. Which of the following involve symbiotic relationships? ruminants mycorrhizae rhizobia rhizobia, mycorrhizae AND ruminants myxobacteria 35. Pollutant degradation may be enhanced by providing dry conditions. providing adequate nutrients. maintaining an acidic pH. lowering the temperature. All of the choices are correct. 36. Why is oil not degraded when in a natural habitat underground, yet susceptible to bioremediation in an oil spill? The bacteria can't be given the right amounts or types of nutrients to foster an increase in their number deep underground. Nearer the surface, human intervention can increase the factors that will raise the microbe quantity. The high pressure the oil is subjected to underground prevents bacteria from growing and consuming it. The bacteria that degrade the oil require a higher than normal salt content, much like what is found in seawater. Underground, they lack this salt level. It IS degraded undergroundbut it happens at a much slower rate because a portion of the cycle is photosynthetic in nature. This process is dramatically increased nearer to the water's surface. 37. Most temperate phages integrate into the host chromosome, whereas some replicate as plasmids. Which kind of relationship do you think would be more likely to maintain the phage in the host cell, and why? Plasmidsthey're smaller, so they'd be easier to replicate by the host cell. Integrationbecause plasmids are frequently lost during cell division, which could leave a daughter cell without the virus genome. Integratedthe host cell would be less likely to view this DNA as "foreign" on subsequent rounds of replication, and would retain it more easily. Plasmidsthese structures often carry other genes that may give the host cell a selective advantage over cells that don't have them.38. During anaerobic decomposition of organic matter with carbon dioxide as the terminal electron acceptor, the primary gas(es) produced is/are methane. hydrogen sulfide. hydrogen. methane AND hydrogen. oxygen. 39. Protozoan classification used to be based on their means of locomotion. growth. obtaining nutrients. reproduction. 40. Is antigenic shift alone likely to lead to influenza pandemics? Noantigenic SHIFT is responsible for changes in the hemagglutinin protein, while antigenic DRIFT is responsible for changes in the neuraminidase protein. You needboth to lead to a pandemic strain. Perhapsbut it would most likely be a mixture of antigenic shift AND drift that would result in a pandemic strain. YesONLY antigenic shift can lead to the largescale mixing of gene elements required to produce a pandemic flu strain. NoONLY antigenic DRIFT can lead to the largescale mixing of gene elements required to produce a pandemic flu strain. 41. Would ID50 and LD50 necessarily be the same for a given virus? Why or why not? No, because very few viruses are lethal, yet many are highly infectious. The two values should ALWAYS be different. Yes, because the number of viruses that infect 50% of a test population should also kill 50% of that test population. No, because a virus may be highly infectious (very low ID50 value) but only marginally lethal (very high LD50 value). A prime example of this is the rhinovirus (common cold virus). Yes, because what we're actually describing here is infection/killing of individual CELLS, not of entire organisms. If a cell is infected, it will always be killed. 42. Explain how nutrientrich runoff can cause waters to become hypoxic. It doesn't. This claim is a scare tactic used by environmental extremists to prevent farmers and individuals from fertilizing their crops and lawns. There is no induction of a hypoxic state in bodies of water where runoff occurs. Algae and cyanobacteria flourish on the nutrients in the runoff, using oxygen in the process. This consumption of oxygen leads to a hypoxic state in the area. Larger animals cannot survive in the hypoxic area. Algae and cyanobacteria flourish on the nutrients in the runoff. Heterotrophic microbes then flourish on the organic molecules produced by these organisms, using oxygen in the process. This consumption of oxygen leads to a hypoxic state in the area. Larger animals cannot survive in the hypoxic area. The nutrients in the runoff often include chemicals that spontaneously oxidize in the presence of oxygen. As such, they tend to deplete the amount of oxygen present in an area simply by being present themselves. This consumption of oxygen leads to a hypoxic state in the area. Larger animals cannot survive in the hypoxic area. 43. Convergent evolutionrefers to the one organism dividing into two AND refers to two different organisms that develop similar characteristics in adaptation to similar environments. explains the morphological similarity yet major genetic differences found between slime molds and fungi AND refers to two different organisms that develop similar characteristics in adaptation to similar environments. refers to one organism dividing into two AND explains the morphological similarity yet major genetic differences found between slime molds and fungi. explains the morphological similarity yet major genetic differences found between slime molds and fungi. refers to two different organisms that develop similar characteristics in adaptation to similar environments 44. The most necessary habitat requirement of protozoa is moisture. UV light. light. 45. temperature. The organisms isolated from hydrothermal vents are typically phototrophs. phototrophs, rhizobia AND bacteroid. rhizobia. chemolithoautotrophs. bacteroid. 46. The problem of not being able to cultivate most microorganisms has led to the use of FISH. microscopy with fluorescent dyes. 16s rRNA analysis. DGGE. All of these methods help identify microorganisms in the environment 47. Which would be more likely to cause illnessa water sample that tested positive for coliforms or one that tested positive for E. coli O157:H7? Neitherthere is usually a small amount of coliforms (including E. coli O157:H7) in all water. The E. coli O157:H7 sample would be more likely to cause illness. This strain of bacterium is highly pathogenic and capable of causing kidney damage. The coliform positive sample would be more likely to cause illness. Coliforms are inherently more pathogenic than the weak O157:H7 lab strain of E. coli. Both would be equally capable of causing illnessall coliforms cause illness. 48. The organisms that convert carbon dioxide into organic matter are the secondary consumers. decomposers. producers. primary consumers. 49. Which statement regarding phage replication is TRUE? A lysogen is a bacterial cell with an integrated prophage. When integrated into host DNA, phage DNA is called a virophage.Lambda is a good example of a lytic phage. Lambda can be a lytic or a temperate phage. 50. In sewage treatment, the removal of phosphates and nitrogen compounds is achieved during advanced treatment. quaternary treatment. primary treatment. secondary treatment.