Ch. 6 quiz

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crenation can result from a change in what?
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in microbio lab, you make three different culture plates: one general purpose plate, one selective media plate, and one differential media plate. unfortunately, you forget to label the different plates, so you do not know which is which. to determine the identity of each plate, you inoculate it with two different strains of lab bacteria. what results would indicate the plate you used was the general purpose media?
in microbio lab, you make three different culture plates: one general purpose plate, one selective media plate, and one differential media plate. unfortunately, you forget to label the different plates, so you do not know which is which. to determine the identity of each plate, you inoculate it with two different strains of lab bacteria. after inoculation, you see that a particular plate has allowed both organisms to grow, but one has changed color. what plate do you think this is?
what would you expect to be a function of MacConkey agar?change the color of some organisms based on their metabolic characteristics and inhibit the growth of certain bacteriaa particular species of bacteria has a generation time of 20 minutes. a microbiologist inoculates a broth with 1000 cells of this bacterium. under ideal growth conditions, what is the minimum amount of time required before the broth contains more than 10,000,000 cells?5 hoursmicrobial growth is at its maximum rate during what phase of the microbial growth curve?log phasewhat technique is most useful for measuring microbial reproduction when the density of a microbial population is very small?membrane filtrationa colony-forming unit is a _________single cell or group of related cells that gives rise to a colonyif it takes two hours for a population of bacteria to grow from 100 cells to 1600 cells, what is the generation time of this bacterial species?30 minutesmicrobes in the _______ phase of the microbial growth curve are most susceptible to antimicrobial drugsloga spectrophotometer is useful for what method of measuring microbial growth?turbiditywhat results when a single bacterium reproduces?two genetically identical daughter cellsif you begin with six cells, how many cells would you have after three rounds of division?48 cellswhich of the following is NOT a step in bacterial cell division? a. disappearance of nuclear envelope b. replication of the genetic material c. cell elongation d. splitting apart of two new daughter cellsawhich step of binary fission is the reason for genetically identical daughter cells?replication of the bacterial chromosomewhat enables the copied chromosomes to separate during binary fission?the chromosomes are attached to different parts of cell membrane, which elongates and thus separates the chromosomeshow long does it take for the daughter cells from one round of replication to replicate themselves?no time is required - they are ready to divide immediately after DNA replication and separation of the daughter cells is complete if conditions are rightput the following steps of bacterial replication in the correct order, starting from a parent cell. 1. cell elongation 2. septum formation 3. chromosome replication 4. separation of daughter cells a. 4, 3, 1, 2 b. 3, 1, 2, 4 c. 1, 4, 3, 2 d. 3, 1, 4, 2bwhat would happen if the septum did not form during binary fission?the parent cell would now have two copies of the chromosomestarting with three cells, how many cells would result from three rounds of replication?24what factors may affect the generation time?temperature, growth media, and bacterial specieswhat is the difference between the direct and indirect methods of determining generation time with a growth curve?in the direct method, the cells are enumerated by determining colony-forming units on a Petri dish; in the indirect method, the cell numbers are approximated using a spectrophotometerwhat is the definition of generation time?the time required for the population to double in sizewhat is happening in the cell during the logarithmic (log) phase?cells are undergoing binary fission, resulting in an exponential increase in the population sizewhat is happening in the cell during the lag phase?the cells are adjusting to their new environment; cellular metabolism is acceleratedwhat is happening in the cell during the stationary phase?the number of cells that are dividing equals the number of cells that are dyingbacteria are said to exhibit logarithmic, or exponential, growth. what does that mean about the growth rate of bacterial populations?since each and every bacterial cell is capable of reproduction, the size of a bacterial population increases by a power of two. in effect, the larger a population gets, the faster it growsquorum sensing is...a process used by bacteria to detect population density and activate genes for new characteristicswhat contributes to osmotic pressure in a cell?waterwhich of these would NOT be considered a growth factor for bacteria? a. amino acids b. phosphorus c. purines and pyrimidines d. vitaminsbwhich of the following is not a toxic form of oxygen? a. hydroxide ion b. singlet oxygen c. superoxide radicals d. peroxide anionsawhich of the following is not a characteristic of a complex medium? a. nutrient broth and trypticase soy agar are examples of complex media b. complex media are especially helpful in growing organisms whose exact nutritional requirements are unknown c. complex media are used for routine growth of many different species of bacteria d. the exact chemical composition is knownda pure culture of bacteria is typically derived from...a colony-forming unitwhy is agar a useful substance in the microbiology lab?it does not solidify until it cools to about 40 degrees Celsiusall of the following are associated with the streak plate method of isolation except a. the purpose is to isolate colony-forming units (CFUs) from one another b. a solid medium in a Petri dish is used in this technique c. colonies will be found growing at and below the surface of the medium d. a sterile inoculating loop or needed is usedcorganisms that use light as their energy source and carbon dioxide as their carbon source are consideredphotoautotrophswhich of the following is not a method for isolating bacteria in a pure culture? a. streak-plate method b. lyophilization c. serial dilutions of broth media d. pour-plate techniquebwhich of these statements does not describe differential media? a. carbohydrate fermentation tubes can be considered differential media b. it is possible for some differential media to also be selective c. blood agar is considered a differential medium d. differential media favor the growth of some organisms while inhibiting the growth of othersdwhy is NADH an important growth factor for microorganisms?it serves as an electron carrier in energy-producing pathwaysa chemostatis a device that maintains a bacterial culture in a particular phase of growthwhich of the following statements concerning nitrogen is false? a. nitrogen is rarely a growth-limiting nutrient b. all cells can recycle nitrogen from their nitrogen-containing molecules c. only a few types of bacteria can engage in nitrogen fixation d. nitrogen is essential for the production of amino acids and nucleotide basesaa psychrophile might grow best in what environment?a refrigeratorwhich growth phase occurs first, after placing an inoculum into a nutrient broth?lag phasesaprobelives on organic matter of dead organismsparasitelives on organic matter of living host; pathogensaerotolerant anaerobesdo not use aerobic metabolism; tolerate oxygen by having some of the enzymes that detoxify oxygen's poisonous forms; can grow equally well with or without oxygen; growth is evenly distributedfacultative anaerobescan grow with or without oxygen, however, their ability to use aerobic respiration pathways enhances their growth near surface; maintain life via fermentation or anaerobic respiration; however, metabolic efficiency is often reduced in the absence of oxygenmicroaerophilesrequire oxygen levels of 2%-10%; damaged by the 21% concentration of oxygen in the atmosphere since they have limited ability to detoxify hydrogen peroxide and superoxide radicalsnitrogen fixationbacteria can reduce nitrogen gas into a more usable form since nitrogen is an essential element for microorganismsdefined mediaprovides exact known amounts of nutrients for the growth of a particular microbeselective mediaeither inhibit the growth of unwanted microorganisms or favor the growth of particular microbesdifferential mediaused to distinguish among groups of bacteriaanaerobic mediafor growing anaerobes; has chemicals that trap molecular oxygen; EX: thyoglycollate bothtransport mediadesigned to move specimens safely from one location to another while maintaining the relative abundance of organisms and preventing contamination of the specimen or environmentrefrigerationbest technique for storing bacterial cultures for short periods of timedeep freezingused for long-term storage of bacterial cultures; involves freezing the cells at temperatures from -50 degrees Celsius to -95 degrees Celsius; can be restored years later by thawing them and placing a sample in an appropriate mediumlyophilizationused for long-term storage of bacterial cultures; involves removing water from a frozen culture using an intense vacuum; can last for decades and are revived by adding lyophilized cells to liquid culture medialogarithmic growththe rapidly growing exponential growth phase of a cell culture; during this bacterial growth phase, the number of new cells appearing are proportional to the populationbinary fissiona form of asexual reproduction in single-celled organisms by which one cell divides into two cells of the same sizegeneration time of bacteriatime required for a single cell to grow and dividelag phasefirst phase of bacterial growth curve; population remains unchanged; cells increasing metabolic activity, making enzymeslog (exponential) phasesecond phase of bacterial growth curve; cells dividing by binary fission; growing by geometric progression, constant rate; most sensitive to drugs and radiationstationary phasethird phase of bacterial growth curve; growth becomes limited by nutrients, inhibitory metabolites or end products, and space; not necessarily quiescence, secondary metabolites, sporulationdeath phaselast phase of bacterial growth curve; death exceeded division; viable cell population declines; exponential declinephotoautotrophsuse carbon dioxide as a carbon source and light energy to make their own foodchemoautotrophsuse carbon dioxide as a carbon source but catabolize organic molecules for energyphotoheterotrophsphotosynthetic organisms that acquire energy from light and acquire nutrients via catabolism of organic compoundschemoheterotrophsuse organic compounds for both energy and carbonorganotrophsacquire electrons for redox reactions from organic sourceslithotrophsacquire electrons from inorganic sourcesobligate aerobesrequire oxygen molecules as the final electron acceptor of their electron transport chains; grow next to airobligate anaerobescannot tolerate oxygen and must use an electron acceptor other than oxygen; grow at bottom away from oxygenosmophileslive in habitats with high solute concentrationhalophilesprefer high salt concentrationsobligate halophilesgrow optimally in solutions of 25% NaCl but require at least 9% NaCl for growthpsychrophilesgrow best at temperatures below 15 degrees Celsius and can even continue to grow at temperatures below 0 degrees Celsius; die at temperatures much above 20 degrees Celsiusmesophilesgrow best in temperatures ranging from 20-40 degrees Celsius, though they can survive at higher and lower temperatures; EX: human pathogensthermophilesgrow at temperatures above 45 degrees Celsius in habitats such as compost piles and hot springshyperthermophilesgrow in water about 80 degrees Celsius; others live at temperatures above 100 degrees Celsius