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Microbiology Exam #2
Chapters 7-9 and 33
| Question | Answer |
|---|---|
| The average generation time of most bacteria under optimum conditions is 24-48 hours. T/F | False |
| At what phase of growth are bacteris best for testing biochemical reactions? At what phase are they most susceptible to antibiotics? | Log phase |
| What counting methods can differentiate between live and dead cells? | Direct microscopic count with a vital stain, such as methylene blue stain, can differentiate between live and dead cells |
| All organic molecules can move freely across the cell wall and membrane. T/F | False |
| Water requires a specialized membrane protein in order to enter or exit a cell. T/F | True |
| A ___________ environment has a higher concentration of solutes outside the cell than. | hypertonic |
| Every microorganism prefers a concentration of 0.5% NaCl in their environment. T/F | False |
| A microorganism with an internal concentration of 5% NaCl, when placed in a concentrations of 0% NaCl, is in ________ environment | hypotonic |
| Obligate _________ inhabit places that are very salty. | halophiles |
| A ___________ can grow in the presence of oxygen but does not require it. | facultative anaerobe |
| Which types of microbes require special culture environments for oxygen? | microaerophiles |
| Quorum sensing changes organism's gene expression when cell density is low. T/F | False |
| What are the major examples of quorum sensing molecules? | autoinducers |
| Bacterial species can only detect other bacteria of the same species. T/F | false |
| An example of a place where quorum sensing occurs is ____________. | biofilms |
| ___________ is disinfection on a living surface. | antisepsis |
| Which shoule be more "harsh" or work better: antisepsis or sanitization? | antisepsis |
| Put in the following in order from most resistant to least resistant: Fungal spores Protozoan cysts Gram positive bacteria Mycobacteria Endospores Enveloped viruses | Endospores mycobacteria protozoan cysts fungal spores gram positive bacteria enveloped viruses |
| Describe the difference between a bactericidal agent and a bacteriostatic agent | bactericidal agents-chemical agents that actively kill bacteria and bacteriostatic agents are chemical agents that inhibit the growth and reproduction of bacteria without necessarily killing them |
| List and describe four factors that affect microbial death rate | -a higher initial population of microbes requires a longer time to be eliminated -environ factors; presence of organic matter can inhibit the action -temp; higher temps increase the effectiveness -conc or dosage of the agent; results in faster death |
| What are the four cellular targets of physical and chemical agents? | -cell wall -cell membrane -cellular synthetic processes -proteins |
| Lower temperatures can be used with dry heat than moist heat. T/F | False |
| The lowest temperature required to kill all of the microbes in a sample in 10 minites is the _______ ________ ________. | thermal death point |
| Cold kills most microbes. T/F | False |
| Filtration is not a method of sterilization. T/F | False |
| Ultraviolet radiation produces ___________ dimers that affect growth by causing _______. | thymine mutations |
| Osmotic pressure achieves sterilization. T/F | False |
| Describe four desirable qualities of a germicide | -rapid action in low conc -solubility in water or alcohol and long term stability -broad spectrum microbial action w/out being toxic -penetration of inanimate surfaces to sustain persistent action |
| Describe 3 factors that affect the actions of a germicide | -number of microorganisms present -the concentration of the germicide -the mode of action of the germicide |
| The most extensively used of all chlorine compound is __________. | hypochlorites |
| Phenol is still extensively used as a disinfectant, T/F | False |
| A higher concentration of alcohol is more effective than a lower concentration. T/F | False |
| List 2 acids used in food preservation. | acetic acid propionic acid |
| Describe four characteristics of an ideal antimicrobial drug. | -should be selectively toxic to the microbe -should be microbial rather than microbiostatic -should remain potent and not be inactivatted -should be reasonably priced and readily available |
| The ______ ______ test shows antimicrobial susceptibility using large agar plates, a bacterial lawn, and antibiotic-infused discs. | kirby-bauer |
| Each species of bacteria has the same susceptibility to a particular drug. T/F | False |
| Identification of the species of bacteria in an infection is necessary to accurately determine antibiotic susceptibility. T/F | True |
| An antibiotic with a therapeutic index of 4 is less toxic than one with a therapeutic index of 40. T/F | False |
| Microbial susceptibility is the only factor in choosing the right drug. T/F | False |
| The type of drug that inhibits cell wall synthesis is a ____ drug. Describe how it works… | beta lactum |
| An antibiotic that acts on the bacterial cell wall will have little effect on a human cell. T/F | True |
| Describe some ways that protein synthesis inhibitors might work… | -binding to the 30S ribosomal subunit to block attachment -binding to 50S ribosomal subunit to prevent formation of peptide -interfering w/ the translocation of the ribosome along the mRNA |
| An antibiotic that acts on the bacterial ribosome will have no effect on a human cell. T/F | False |
| Describe some adverse reactions to antimicrobials. | -toxicity-damage to organs -allergies-hypersensitivity reactions -disruption of the normal microbiota |
| The _______ account for the greatest number of drug allergies. | penicillins |
| Overgrowth of certain microbes due to antibiotic therapy that cause infection is known as _____. | superinfection |
| The LEAST selectively toxic antibiotics are… | polymyxins |
| Bacteria can be resistant to antibiotics without ever encountering the drug. T/F | True |
| List and describe the five mechanisms of antibiotic resistance. | -inactivation of the drug -decreased permeability -activation of drug pumps -modification of the target -use of alternative metabolic pathways |
| What is a superbug? | strain of bacteria that has developed resistance to multiple types of antibiotics, making it very difficult to treat w/conventional drugs |
| Many antibiotics prescribed to humans are for viral infections. T/F | False |
| Nearly 80% of all antibiotics in the US are given to ________. | livestock |
| ________ are a novel treatment that have been used to target specific bacteria and effectively treat bacterial infections. | Bacteriophages |
| A patient presents to your clinic with abdominal pain, photosensitivity, dizziness, and several rashes. He recently began a course of trimethoprim for an uncomplicated middle ear infection. This description most likely describes: | side effects of the antibiotic trimethoprim |
| Your gut biota can partially determine your mood and mental health. T/F | True |
| How do species of the microbiota become pathogenic? | Opportunistic pathogens |
| Babies born by caesarian section are colonized by the same biota as babies born vaginally. T/F | False |
| A skewing of the microbiota populations in the body that leads to disease is called __________. | dysbiosis |
| What are sites in the body that are known to have microbiota? Sites where we suspect there is, but detection is difficult? | skin, gut, oral cavity, RT, and Urogenital tract difficult detection in the placenta, fetal gut, and breast tissue |
| What are current possible treatments that adjust the microbiota? | Probiotics, prebiotics, and fecal microbiota transplantation |
Created by:
vtlove116
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