Mic 205 Exam 2 Questions Answered Correctly Latest Update 2026

MIC 205 EXAM 2 QUESTIONS ANSWERED CORRECTLY LATEST UPDATE 2026 Increase in cell number - Answers though growth typically refers to increase in size of an organism, applied to microbes the term refers to an Logarithmic growth - Answers bacterial populations can increase to millions of cells in only a few hours clinical specimens considerations - Answers human materials examined or tested for presence of bacteria and other microbes; proper specimen, technique, timely delivery, proper culture methods Selective Media - Answers slightly acidic, selects for fungi by inhibiting bacterial growth Differential Media - Answers digestion of red blood cells microbes are often... - Answers classified to their nutritional and physical requirements Phototrophs - Answers acquires energy from sunlight Chemotrophs - Answers acquires energy from organic/inorganic molecules Autotrophs - Answers "self feeders"; make their own food; fixing CO2 Heterotrophs - Answers "different feeders"; get carbon from other organisms Toxic forms of oxygen initiate... - Answers chains of oxidation reactions that cause irreparable damage to a cells proteins and lipids Singlet Oxygen - Answers electrons boosted to higher energy state; aerobic metabolism Superoxide radicals - Answers incomplete reduction of oxygen in aerobic and anaerobic respiration Superoxide dismutase (SOD) - Answers removes superoxide radicals Peroxide anion - Answers formed during breakdown of lipids and in reactions catalyzed by SOD; highly reactive; removed by catalase Hydroxyl radical - Answers results from ionizing radiation and from incomplete reduction of hydrogen peroxide; most reactive form Nitrogen Fixation - Answers some gram- bacteria grow in association with plant roots, where they convert nitrogen gas in the atmosphere into ammonia; process is essential to life on Earth because most organisms cannot use gaseous nitrogen Azospirillum - Answers tropical grasses (sugarcane) Rhizobium - Answers legumes (peas, beans, clover) Phosphorus - Answers required phospholipid membranes, DNA, RNA, ATP, and some proteins Sulfur - Answers component of sulfur-containing amino acids (cysteine and methionine) and vitamins (thiamin and biotin) Trace elements - Answers minerals and inorganic ions; usually found in sufficient quantities in tap water Growth factors - Answers organic chemicals that cannot be synthesized by certain organisms (vitamins, certain amino acids, nitrogenous bases in nucleotides, NADH, cholesterol, heme, etc) Thermal energy - Answers plays a crucial role in the structure and function of a cells proteins and membranes microbes absolutely require... - Answers water to dissolve enzymes and nutrients utilized in metabolism Obligate halophiles - Answers grow in up to 30% salt Facultative halophiles - Answers can tolerate high salt concentrations Barophiles - Answers organisms that live under extreme pressure pure cultures are - Answers absent or virtually so in nature Sessile organisms - Answers microbes that are attached to a surface planktonic organisms - Answers microbes that are free living Characteristics of Biofilms - Answers microbial community attached to a surface; complex social structure; 1000x resistant to antibiotics; biofilm is a molecular filter; low metabolism Common Biofilms - Answers Plaque on teeth; contact lenses; sewage; slippery river stones 60-80% of all bacterial infections are caused by bacteria in the biofilm form - Answers pacemakers - Answers Staphylococcus aureus Cystic fibrosis pneumonia/burn patients - Answers Pseudomonas aeruginosa Urinary catheters - Answers Escherichia coli Orthopedic devices/breast implants - Answers stayphylococcus epidermidis Contact lenses - Answers many gram positive bacteria Quorum Sensing - Answers gene regulation is controlled by Cell to cell signaling - Answers allow an individual bacterium to monitor the cell density of the population of bacteria by the production of autoinducer autoinducer - Answers allow the regulation of specific genes furanones - Answers produced by red algae; block homoserine lactone signaling molecules Sterilization - Answers complete removal of all microbes aseptic - Answers producing sterile conditions in a lab/healthcare setting Disinfectant - Answers removal of most but not all microbes; heavily reduce number of microbes present on a surface/inanimate objects; uses chemicals Antiseptic - Answers removal of microbes from human surfaces; most but not al microbes Degerming - Answers physical removal of microbes via scrubbing action Sanitation - Answers disinfection of public surfaces Pasteurization - Answers disinfection by use of gentle heating stasis/static - Answers control growth; do not always kill cidal/cide - Answers agents that kill microbial agents - Answers kill a constant percentage of cells over time, rather then simultaneously killing all cells Ideal antimicrobial agent - Answers inexpensive, fast acting, stable during storage, broad spectrum, harmless to humans/animals/objects effectiveness of antimicrobials depends upon - Answers nature of site to be treated; susceptibility and number of microbes involved; environmental conditions during application fewer organisms= - Answers faster sterility High-level germicides - Answers kill ALL pathogens, including endospores Intermediate-level germicides - Answers kill fungal spores, protozoan cysts, viruses and pathogenic bacteria Low-level germicides - Answers kill vegetative bacteria, fungi, protozoa, and some viruses most resistant microorganisms - Answers prions, bacterial endospores, mycobacteria most susceptible - Answers enveloped viruses, gram + bacteria, nonenveloped viruses Action of Antimicrobial Agents - Answers alterations of cell walls/cell membranes; interference with protein and nucleic acid structure Damaged cell wall - Answers cannot prevent cell from bursting due to osmotic effects Damaged cell membrane - Answers cannot contain cytoplasm or control passage of chemicals; cellular contents leak out Proteins unfolded (denatured) - Answers by extreme heat and certain ENZYMES are unable to function Nucleic acids altered (mutated) - Answers by heat, chemicals, and radiation are fatal to reproductive cycles Diffusion Susceptibility Tests - Answers method used for testing the effectiveness of antimicrobial agents on specific microbes Effects of high temperatures - Answers denaturation of proteins, interference with integrity of cell walls and membranes, disruption of structure and function of nucleic acids Incineration - Answers Ultimate means of sterilization moist heat - Answers more effective than dry heat; water is a better conductor of heat than air Historical (batch) method - Answers 30 minutes at 63º C Flash Pasteurization - Answers 15 seconds at 72 º C ultrahigh-temperature pasteurization - Answers 1 second at 134 º C Dry heat sterilization - Answers 2 hours at 180 ºC chemical reactions occur slower at lower temps - Answers enzymes are less functional; liquid water is less readily available Which type of microorganisms would be capable of multiplying in refrigerated foods? - Answers psychrophiles Lyophilization - Answers freeze dying; can prevent ice crystal formation by removing water at cold temps hole size - Answers 0.22 um HEPA filters - Answers High Efficiency Particulate Air filters Radiation - Answers shorter wavelength equals more energy and greater penetration UV light - Answers lab applications; works well on surfaces, transparent fluid and gases Gamma rays - Answers food industry Chemical methods of microbial control - Answers Affect microbes' cell walls, cytoplasmic membranes, proteins, or DNA Phenols/Phenolics - Answers Denature proteins and disrupt cell membranes; lysol, pinesol, soap Alcohols - Answers Denature proteins and disrupt cell membranes by removing water from cells; hand sanitizer Halogens - Answers damage enzymes via oxidation or by denaturing them; clorox, Betadine Heavy metals - Answers ions that alter the 3-D shape of proteins, inhibiting or eliminating their function; Surfactants - Answers reduce surface tension of solvents to make them more effective at dissolving solutes; Tide (good degerming agent) Oxidizing Agents - Answers oxidize microbial enzymes and cell membrane lipids; H202 Aldehydes - Answers cross link with amino, hydroxyl, sulfhydryl, and carboxyl groups to denature proteins and inactivate nucleic acids; formaldehyde Gaseous agents - Answers denature proteins and DNA by cross linking functional groups; ethylene oxide Cell wall synthesis - Answers penicillins, cephalosporins, bacitracin protein synthesis - Answers erythromycin, tetracylcine, streptomycin membrane structure - Answers polymyxins nucleic acid synthesis - Answers rifampicin, novobiocin, quinolones other metabolic pathways - Answers trimethoprim, sulfanilamide DNA - Answers functions as the genetic material of all organisms and of many viruses Genome - Answers entire genetic complement of an organism; includes nucleotide sequences of genes