Biology of Microorganisms - Test One Answers | BY 271, Exams of Biology

Download Biology of Microorganisms - Test One Answers | BY 271 and more Exams Biology in PDF only on Docsity! BY 271 Test #1 9/23/2010 1. The sum total of all chemical reactions occurring in a cell is called _____. A. anabolism B. catabolism C. metabolism D. none of the choices A. is wrong because it is only one component of metabolism. Anabolism is the sythesis of complex organic molecules from smaller inorganic and organic compounds. It requires energy from fueling reactions (catabolic reactions). B. is wrong because it is only one component of metabolism. Catabolism consists of fueling reactions and energy-conserving reactions that provide ready source of reducing power (electrons) and generate precursors for biosynthesis. C. is correct because metabolism is defined as the total of all chemical reactions in the ell and is divided into two parts: catabolism and anabolism. CHAPTER 9 2. Some archaeal cells have a cell membrane composed of a monolayer of lipids. A. True B. False Archael membranes are composed of unique lipids (isoprene units [five C, branched] and ether linkages rather than ester linkages to glycerol). Some archaea have a monolayer structure instead of a bilayer structure. CHAPTER 3 3. The plasma membrane of eukaryotes contains all of the following except: A. phosphoglycerides B. sphingolipids C. sterols D. peptidoglycan Eukaryotic cell envelopes consist of the plasma membrance and all coverings external to it. The plasma membrane is a lipid bilayer whose major membrane lipids include phosphoglycerides, sphingolipids, and cholesterol, all of which contribute to strength of membrane. D. is wrong because peptidoglycan (aka murein) is unique to Domain Bacteria in their cell walls. CHAPTER 4 4. Which is not true of viruses? A. They can exist in an intracellular or extracellular phase B. They infect animal and plant cells only C. They can be observed with an electron microscope. D. They are acellular. E. They replicate only inside host cells. A. is true since viruses (aka virions, which means a complete virus particle) must replicate and assemble new virions inside cells (intracellularly). Some viruses that enter the lytic cycle are released from the cell and float about outside the cell until the next potential host (extracellular phase). B. is false since virions can infect all cell types (bacteriophages are bacterial viruses; archael viruses; and the most characterized are eukaryotic viruses). C. is true since most viruses MUST be viewed with an electron microscope. D. is true since viruses, or virions, fall under the category of acellular agents. E. is true since viruses cannot reporduce independent of living cells nor carry out cell division (although they can exist extracellularly). CHAPTER 5 5. The _____ is a group of proteins needed for DNA synthesis that assembles at the origin of replication. A. septum B. replisome C. prospore D. none of the above A. is false because the septum is a partition or cross-wall that occurs between two cells in a prokaryotic or fungal filament, or which partitions structures such as spores. A septum also divides a parent cell into two daughter cells during binary fission. B. is correct since the replisome is a group of proteins needed for DNA synthesis during chromosome replication. The replisome pushes daughter chromosomes to opposite ends. C. is false since a prospore is a double-membraned structure that extends from the cytoplasmic face of the spindle pole bodies to encompass the spindle pole bodies and the four nuclear lobes that are formed during meiosis. It helps isolate the meiotic nuclei from the cytoplasm during spore formation and serves as a foundation for the formation of the spore walls. Not only is C really wrong, it’s not even mentioned in the friggin book. CHAPTER 7 6. Cells carry out three major types of work; which of the following involves the synthesis of macromolecules as well as the breakdown of substances for their energy? A. Chemical work B. Transport work C. Mechanical work D. None of the above. A. is correct since chemical work is the synthesis of complex molecules (anabolism). B. is wrong since transport work is the take up of nutrients, elmination of wastes, and maintenance of ion balances. C. is wrong since mechanical work is involved in cell motility and the movement of structures within cells (e.g. chromosomes). CHAPTER 9 7. A complete virus particle is called a _____. A. capsid B. nucleocapsid C. virion D. cell. A. is wrong since the capsid, or protein coat enclosing the virion’s genetic material, makes up only a portion of a complete virus particle. Capsids are large macromolecular structures which serve as protein coats of viruses. They protect viral genetic material and aids in its transfer between host cells. They are made of protein subunits called protomers. B. is wrong since a nucleocapsid is only one component of an entire complete virus particle. The nucleocapsid is the entire genome of a virus. It varies between naked or enveloped viruses. C. is right because a virion by definition is a complete virus particle that consists of the nucleocapsid and the capsid. D. is wrong because… well you better know this one. CHAPTER 5 8. Bacterial cells that are variable in shape are called _____. A. vibrio B. pleomorphic C. coccobacilli D. hyphal A. is wrong since vibrio describes any bacterial cells that resemble comma-shaped rods. B. is correct since pleomorphic is defined as organisms that are variable in shape. Pleo- means many/multiple and morphic refers to shape. C. is wrong since coccobacilli describes bacterial cells that resemble very short rods. D. is wrong since hyphal means rootlike and refers to fungi. CHAPTER 3 9. Protein filaments with a diameter of about 10 nm that are major components of the cytoskeleton are called: A. microtubules B. microfilaments C. intermediate filaments D. mycelia A. is wrong because microtubules are cytoskeletal structures that are shaped like thin cylinders and measure about 25 nm in diameter. Microtubules consist of alpha and beta tubulin proteins. They help maintain cell shape, involved with microfilaments in cell movements, and participate in intracellular transport processes. B. is wrong since microfilaments (which are made of actin proteins) are the smallest cytoskeletal structures. Microfilaments are minute protein filaments measuring 4-7 nm in diameter. They are involved in cell motion and shape changes. C. is wrong because murein/peptidoglycan is found in both gram + and – cell walls. CHAPTER 3 17. Microorganisms are most nearly uniform in terms of chemical and physiological properties during _____ phase. A. lag B. exponential C. stationary D. decline A. is wrong because the lag phase is involved in synthesizing new components for the cell (replenish spent materials and adapt to new medium or other conditions). Lag phases vary in length; in some cases, they can be very short or even absent. B. is correct because the exponential phase (aka the log phase) is where the rate of growth and division is constant and maximal. During this phase, the population is most uniform in terms of chemical and physical properties. C. is wrong because the stationary phase is a closed system population growth that eventually ceases, although the total number of viable cells remain constant. The active cells stop reproducing. The reproductive rate is balanced by death rate. D. is wrong because… well it is… The growth curve is observed when microorganisms are cultivated in batch culture. It has 4 distinct phases – lag, exponential, stationary, senescence, and death. I think the decline phase could be senescence. CHAPTER 7 18. Proteins are synthesized on structures called _____. A. mesosomes B. lysosomes C. ribosomes D. chromosomes A. is wrong because a mesosome is not even involved in translation. It is an organelle of bacteria that appears to be an invagination of the plasma membrane and is a site of localization of respiratory enzymes. B. is wrong because lysosomes are membrane-bound vesicles found in most eukaryotes. They are involved in intracellular digestion and contain hydrolases, enzymes that hydrolyze molecules and function best under slightly acidic conditions. They maintain an acidic environment by pumping protons into their interior. C. is correct because ribosomes are the site of protein synthesis and consist of a small and large subunit. D. is wrong because chromosomes are the densely compacted form of histone proteins and DNA. CHAPTER 12 19. Larger populations generally are killed as rapidly as smaller populations. A. True B. False I honestly cannot find the reasoning behind this one supported in his powerpoints but it has to be a who is bigger Daniel or Goliath type of question. Anyways lemme know if you find anything 20. Immersion oil is used to prevent a specimen from drying out. A. True B. False Immersion oil is used to increase microscope resolution. If air replaced with immersion oil, many light rays that did not enter the objective due to reflection and refraction at the surfaces of the objective lens and slide will now do so. This results in an increase in resolution and numerical aperture. CHAPTER 2 21. The change in _____ is the amount of energy in a system that is available to do work. A. entropy B. enthalpy C. free energy D. synergy SELF EXPLANATORY in CHAPTER 9 22. Proteins that are embedded within the cytoplasmic membrane and not easily extracted are called _____ proteins. A. peripheral B. integral C. external D. internal A. is wrong because peripheral proteins are membrane proteins that are loosely connected to the membrane and can be easily removed. B. is correct because integral proteins are amphipathic (amphipathic molecules contain both hydrophilic and hydrophobic regions) proteins embedded within the membrane. CHAPTER 3 23. Who of the following provided the evidence needed to discredit the concept of spontaneous generation? A. Pasteur B. Koch C. Semmelweiss D. Lister A. is correct because Pasteur conducted an experiment that involved putting broth in curved, long necked flasks. B. is wrong because Koch established the relationship between Bacillus anthracis and anthrax and developed Koch’s postulates. He did not have anything to do with spontaneous generation. C. is wrong because I have never heard of him. D. is wrong because Joseph Lister provided indirect evidence that microorganisms were the causal agents of disease. He used phenol to prevent microorganisms from entering wounds and treat instruments and surgical dressings. CHAPTER 1 24. Which of the following environmental factors generally do(es) not have an impact on the efficiency of an antimicrobial agent? A. pH B. presence or absence of a biofilm C. concentration of organic matter D. refractive index A, B, and C all play a role in the efficiency of an antimicrobial agent. Local environmental factors, such as pH, viscosity, and concentration of organic matter, can profoundly impact effectiveness. Heat is more effective in an acidic environment. Organisms in biofilms (organix matter) are physiologically altered and less susceptible to many antimicrobial agents. D. is correct because refractive index has absolutely nothing to do with controlling microbe growth. CHAPTER 8 25. Lipids with polar and nonpolar ends are said to be _____. A. amphipathic B. amphibolic C. bilateral D. none of the choices. A. is correct because amphipathic means to have polar ends (hydrophilic) and nonpolar ends (hydrophobic) ends. Amphibolic is used to describe a biochemical pathway that involves both catabolism and anabolism. CHAPTER 3 26. The instrument that produces a bright image of the specimen against a dark background is called a (n) _____ microscope. A. phase-contrast B. electron C. bright-field D. dark-field A. is wrong because phase-contrast microscopes convert slight differences in refractive index and cell density into easily detected variations in light intensity. These are perfect for observing living cells (motility and intracellular structures). B. is wrong because electron microscopes use electrons instead of light as the illuminating beam. The wavelength of electron beam is much shorter than light, resulting in much higher resolution. C. is wrong because bright-field microscopes produce a dark image against a brighter background. D. is correct because dark-field microscopes form images by light reflected or refracted by the specimen. It produces a bright image of the object against a dark background. CHAPTER 2 27. Lysosomes maintain an acidic environment by actively pumping protons into their interior. A. True B. False NUFF SAID but it’s found in CHAPTER 4 28. Antiseptic surgery was pioneered by _____. A. Pasteur B. Lister C Jenner D. Kitasato I have explained what the other guys have talked about. Kitasato, along with Emil von Behring, developed antitoxin for diphtheria and tetanus. 29. Moist heat sterilizes by _____. A. causing the formation of thymine dimers B. denaturing proteins C. causing production of singlet oxygen D. all of the choices Moist heat sterilization destroys viruses, fungi, and bacteria. The process involves boiling for 10 minutes and will destroy vegetative cells and eukaryotic spores. It does not kill bacterial spores. Boiling does not sterilize but can disinfect. Moist heat degrades nucleic acids, denatures proteins, and disrupts membranes. A is wrong because UV radiation causes thymine dimmers, preventing replication and transcription. 30. The _____ is the electron donor in a redox reaction. A. reductant B. oxidant C. enzyme D. product Oxidation-reduction reactions (redox) transfer of electrons from a donor (reducing agent) to an acceptor (oxidizing agent). 31. The series of enzymatic steps that fixes carbon dioxide into carbohydrate is called the _____. A. Pentose phosphate pathway B. Embden-Meyerhoff pathway C. Calvin cycle D. Entner-Doudoroff pathway A and B are both amphibolic pathways involved in the breakdown of glucose to pyruvate. D is a catabolic pathway involved in the breakdown of glucose to pyruvate. C is right because the Calvin cycle, an anabolic pathway, involves the fixation of CO2 by autotrophs. The Calvin cycle is used by most autotrophs to fix CO2. The Calvin cycle is also called the reductive pentose phosphate cycle. Summary: 6CO2 + 18ATP + 12NADPH + 12H+ + 12H2O => glucose + 18ADP + 18Pi + 12NADP+ CHPTER 11 32. Gram-positive bacteria have a structurally and chemically more complex cell wall than gram-negative bacteria. A. True B. False Gram positive bacteria stain purple and have thick peptidoglycan cell wall. Gram negative bacteria stain pink or red and have a thin peptidoglycan cell and outer membrane. Gram-negative cell walls are more complex than G+; they consist of a thin layer of peptidoglycan surrounded by an outer membrane composed of lipids, lipoproteins, and lipopolysaccharide (no teichoic acids). CHAPTER 3 33. The first product to be commercially treated by pasteurization was _____. A. milk B. wine C. beer D. cheese Pasteur developed the process of pasteurization to preserve wine during storage. CHAPTER 1 34. Which of these methods can be used to determine the number of viable microorganisms in a sample? A. light scattering in a spectrophotometer B. measuring total cell mass C. measuring colony forming units per ml D. counting a known volume of cells in a hemocytometer Measurement of microbial growth can measure changes in number of cells in a population and can measure changes in mass of population. Direct cell counts involve counting chambers, electronic counters, and on 43. Basic dyes such as methylene blue bind to cellular molecules that are _____. A. hydrophobic B. negatively charged C. positively charged D. aromatic. Dyes make internal and external structures of cell more visible by increasing contrast with the background. Have 2 common features: chromophore groups (chemical groups with conjugated double bonds and give dye its color) and ability to bid to a part of a cell. Ionizable dyes have charged groups. Basic dyes have positive charges and acid dyes have negative charges. In a simple staining, only a single stain is used. Methylene blue is a type of basic dye and therefore must bind to negative particles. 44. _____ membranes allow some molecules to pass but not others. A. Permeable B. Inverted monolayer C. Selectively or semi-permeable D. Impermeable Self-explanatory BUT if you have anything to add just tell me 45. Organisms that grow well at 0C and have optimum growth temperatures of 15C or lower are called: A. psychrotrophs B. psychrophiles C. zerophiles. D. mesophiles. psychrophiles – 0o C to 20o C psychrotrophs – 0o C to 35o C mesophiles – 20o C to 45o C thermophiles – 55o C to 85o C hyperthermophiles – 85o C to 113o C CHAPTER 7 46. _____ media contains some ingredients of unknown chemical composition. A. undefined B. complex C. defined D. synthetic Defined or synthetic media is media in which all components and their concentrations are known. Complex media contain some ingredients of unknown composition and/or concentration. CHAPTER 6 47. Which of the following can be used as electron acceptors during anaerobic respiration? A. nitrate B. sulfate C. carbon dioxide D. all of the choices An example of anaerobic respiration is dissimilatory nitrate reduction, which uses nitrate as terminal electron acceptor. Denitrification is the reduction of nitrate to N gas. Anaerobic respiration involves any final electron acceptor is NOT oxygen: nitrate, sulfate, carbon dioxide, iron, and SeO4^-2. Organic acceptors (fumarate or humic acids) may also be used. CHAPTER 10 48. The reduction of atmospheric nitrogen to ammonia is called _____. A. ammonification B. nitrification C. denitrification D. nitrogen fixation. A. is wrong because I don’t even know if it exists. B. is wrong because nitrification might also be fake. C. is wrong because denitrification is the reduction of nitrate to nitrogen gas. In soil, this causes loss of soil fertility. D. is right because nitrogen fixation involves the reduction of atmospheric nitrogen (N2) to ammonia (NH4) CHAPTER 10 49. A growth medium that distinguishes among different groups of bacteria on the basis of their biological characteristics is called a _____ medium. A. selective B. differential C. enrichment D. transport A. is wrong because selective media favors the growth of some microorganisms and inhibit growth of others (ex. MacConkey agar selects for gram-negative bacteria). B. is correct because differential media distinguishes between different groups of microorganisms based on their biological characteristics (ex. Blood agar distinguishes hemolytic versus nonhemolytic bacteria). C. is wrong because enrichment media’s general purpose is media supplemented by blood or other special nutrients (ex. Blood agar). NO such thing as transport media. CHAPTER 6 50. Construction of flagella and/or cilia is directed by the _____. A. axoneme B. tubulin C. centriole D. basal body An axoneme is a set f microtubules in a 9+2 arrangment. Tubulin is the protein that makes up microtubules. Centrioles are involved in cellular division and along with microtubules, make up the centrosome (aka the microtubule organizing center). D. is correct because basal body, which is at the base of flagellum or cilium, directs synthesis of flagella and cilia. 51. Purines and pyrimidines are precursors for synthesis of _____. A. fatty acids B. nucleic acids C. proteins D. peptidoglycan A. Fatty acids are synthesized then added to other molecules to form other lipids such as triacylglyerols and phospholipids. B. Nucleic acid examples are DNA and RNA. They are made up of purines and pyrimidines. C. Proteins (also known as polypeptides) are organic compounds made of amino acids arranged in a linear chain and folded into a globular form. The amino acids in a polymer are joined together by the peptide bonds between the carboxyl and amino groups of adjacent amino acid residues. D. peptidoglycan (aka murein) is a meshlike polymer of identical subunits forming long strands with two alternating sugars (NAG or N-acetylglucosamine and NAM or N-acetylmuramic acid) and alternating D and L amine acids. CHAPTER 3 52. Fatty acids are metabolized by the _____ pathway. A. alpha-oxidation B. beta-oxidation C. gamma-oxidation D. delta-oxidation In lipid catabolism, triglycerides (common energy sources) are hydrolyzed to glycerol and fatty acids by lipases. Glycerol is degraded via glycolytic pathway. Fatty acids often oxidized via beta-oxidation pathway. CHPTER 10 53. The Gram-staining procedure is an example of _____. A. simple staining B. negative staining C. differential staining D. fluorescent staining A simple staining procedure involves only one stain (basic dyes). Negative staining involves capsules that are colorless against a stained background. Capsule staining is used to visualize capsules surrounding bacteria. C. is correct because differential staining divides microorganisms into groups based on their staining properties (ex. Gram stain and acid-fast stain). Differential staining is used to detect the presence or absence of structures or components (endospores, flagella, capsules). Gram staining is the most widely used differential staining procedure. Fluorescent involves fluorescent dyes as tags. 54. All fastidious microorganisms require which of the following for growth? A. oxygen B. temperatures near normal for the human body C. extra nutrients (such as whole blood) D. iron The key word to remember here is fastidious. Fastidious in microbiology refer to microbes having complicated nutritional requirements, usually they require extra nutrients. 55. The genetic code is expressed differently in bacterial and archaeal cells than in eukaryotic cells. A. True B. False The genetic code (DNA) is universal across all species. 56. Although heavy metals are no longer widely used as germicides, _____ is still used to prevent ophthalmic gonorrhea. A. lead acetate B. copper sulfate C. silver nitrate D. mercuric chloride Heavy metals (mercury, silver, arsenic, zinc, and copper) are usually very effective in treatment but usually toxic. Silver nitrate (1% sol) is used to prevent ophthalmic gonorrhea. Silver sulfadiazine is used on burns. Copper nitrate is an effective algicide in lakes. CHAPTER 8 57. If an enzyme consists of a protein component and a non-protein component, the protein component is referred as the _____. A. apoenzyme B. coenzyme C. holoenzyme D. prosthetic group. An apoenzyme is a protein component of an enzyme. A cofactor is a nonprotein component of an enzyme (prosthetic group – firmly attached; coenzyme – loosely attached). A holoenzyme is an apoenzyme + cofactor. CHAPTER 9 58. Organisms that require high levels of sodium chloride in order to grow are called barophilic organisms. A. True B. False Barotolerant microbes are adversely affected by increased pressure, but not as severely as nontolerant organisms. Barophilic (peizophilic) organisms require or grow more rapidly in the presence of increased pressure. These organisms change membrane fatty acids to adpt to high pressures. Baro refers to pressure. However, halophiles grow optimally in the presence of NaCl or other salts at a concentration above about 0.2 M. Extreme halophiles require salt concentrations of 2M and saturation; they also live in extremely high concentrations of potassium. CHAPTER 7 59. Enzymes catalyze a reaction by _____. A. decreasing the amount of energy released by the reaction B. increasing the amount of energy released by the reaction C. decreasing the activation energy of the reaction D. increasing the activation energy of the reaction. Self-explanatory but the chapter is 9 60. Which of the following diseases is (are) caused by prions? A. scrapie B. mad cow disease C. kuru and Creutzfeldt-Jakob Disease D. all of the choices Prions are proteinaceous infectious particles. They cause a variety of degenerative diseases in humans and animals, such as scrapie in sheep, bovine spongiform encephalopathy (BSE) or mad cow disease, kuru, and Creutzfeldt-Jakob disease (CJD) and variant CJD.