Micro Lab Final 1012-91 Al-Dujaili LSUE

Micro Lab Final 1012-91 Al-Dujaili LSUE Cotton plugs or screw caps are used in test tubes containing sterile media or pure cultures to... - ✔✔-prevent unfiltered air or dust particles from entering the tubes -maintain ...

Micro Lab Final 1012-91 Al-Dujaili LSUE Cotton plugs or screw caps are used in test tubes containing sterile media or pure cultures to... - ✔✔-prevent unfiltered air or dust particles from entering the tubes -maintain anaerobic conditions -and prevent culture from spilling *all of the above* If the pH of the medium is higher than 7.0, you can adjust to 7.0 by: - ✔✔adding drops of HCL to *lower* it or NaOH to *raise* it The pH indicator in Simmons Citrate agar is what? - ✔✔Bromothymol blue bacteria that show no preference, grow equally well in aerobic or anaerobic conditions are - ✔✔facultative what protein gives milk its white color? - ✔✔casein (from the milk biology handout) beef extract is a source of: - ✔✔-salt -carbohydrates -vitamins *all of the above* bacteria that grow in the dark and in media composed mainly of organic compounds are - ✔✔heterotrophic media that allows *one type* of bacteria to grow on them while preventing growth of other types of bacteria is called - ✔✔selective media a medium that contains substances whose exact chemical composition is known is called a - ✔✔synthetic medium a microorganism that grows in the presence of a very low concentration of free oxygen is known as a *they are poisoned by high concentrations of oxygen. They gather in the upper part of the test tube but not the very top.* - ✔✔microaerophile which of the following statements is most nearly true of heterotrophic organisms compared to autotrophs? - ✔✔heterotrophs have greater synthetic ability the ability of organisms to hydrolyze starch is accompanied with the enzyme: - ✔✔amylase If a microbe produces gas when it utilizes glucose, the presence of this gas can be determined by: - ✔✔use of a Durham tube a fluid thioglycollate medium is one that determines the ________ __________ of bacteria - ✔✔oxygen requirements When talking about the VP test, butanediol fermentation takes place and acetone is one of the products formed. What is the chemical nomenclature of an acetoin end product? - ✔✔2,3 butanediol (yes, it is supposed to be a comma) Which of the following can you detect from an SMI test? - ✔✔-if the bacteria inhibits motility -can produce sulfate -form indoles (from the amino acid tryptophan) *all of the above* lactose fermentation is indicated on a phenol red lactose medium turning a ________ color - ✔✔yellow what is the action of breaking down protein? - ✔✔proteolysis what problem could occur if we made all inoculations for the single tube given to us? - ✔✔-contamination -aging of the culture -microbes in the culture may die *all of the above* yeast broth is a combination of - ✔✔yeast extract and nutrient broth in general, all cellular activities are mediate by which of the following? - ✔✔enzymes organisms that use carbon dioxide as their sole or principle source of carbon are - ✔✔autotrophs Media containing some ingredients of unknown chemical composition are called __________ media. - ✔✔complex Growth media that are supplemented by rich nutrient sources in order to support the growth of organisms with fastidious culture requirements are called __________ media. - ✔✔enriched media *none of the above on exam* which of the following can be used to isolate pure cultures of bacteria from mixtures: - ✔✔-spread plate -streak plate -pour plate *all of the above* __________ are the compounds most widely used by fermenting organisms - ✔✔sugars (glucose) the solidity material used in solid or semi-solid media is: - ✔✔agar fastidious microorganisms have - ✔✔complex nutritional requirements a common product of glycolysis is - ✔✔Pyruvic acid Solid culture media from isolation of bacteria was first used in the laboratory of ______ - ✔✔Koch which of the following would *not* be a product of fermentation? - ✔✔Pyruvic acid during aerobic respiration, the final hydrogen acceptor molecule is - ✔✔oxygen suppose that you see a (Gram-stained) field of red rods and blue cocci through the microscope. You can most safely conclude that you have - ✔✔made a mistake in staining/ the sample has a mixed culture you are trying to identify an unknown Gram-negative bacterium. Which of the following stains is not necessary: - ✔✔acid-fast and endospore stain you have isolated a Gram-negative rod. The next thing you should do is determine - ✔✔whether it is motile the visible accumulations of bacterial cells on a solid medium's surface are called - ✔✔colonies the enzyme that catalyzes the reaction: 2H2O2--> 2H2O + O2 is... - ✔✔catalase the black precipitate that may form on the test tube containing SIM medium consists of: - ✔✔H2S also called ferrous sulfate An inverted vial, the Durham tube is placed in each carbohydrate broth to collect ___ - ✔✔gas For separating bacteria and allowing them to grow into isolated colonies, microbiologists utilize ___ media. - ✔✔solid gram positive cells in old cultures will generally - ✔✔-exhibit greater permeability to the crystal violet -decolorize more readily -tend to show more gram negative adequate anaerobic culture can be achieved by which of the following? - ✔✔Both A and B; -Removal of free oxygen from a microorganism's immediate environment -Maintenance of a low oxidation-reduction potential gas production in a liquid carbohydrate medium can be detected with the use of which of the following: - ✔✔Durham tube Name the indicator used in the prepara