Download MICROBIOLOGY MIDTERM EXAM QUESTIONS 2025 and more Exams Nursing in PDF only on Docsity!
QUESTIONS 2025
Lab safety protocol - correct answers - eating, drinking, and smoking are NOT allowed
- long hair must be tied back
- no sleeveless tops/ thighs should be covered
- must know all exits of the lab
- lab benches must be sprayed with bleach before and after use
- put away all staining reagents IMMEDIATELY after use Nosocomial infections - correct answers hospital acquired infections Nosocomial infections' role in the spread of contagious diseases - correct answers nosocomial infections are infections that develop as a result of a stay in the hospital or are produced by microorganisms and viruses acquired during hospitalization Why is agar a good ingredient for converting liquid media to solid media - correct answers agar remains solid during bacterium incubation and generally bacteria cannot breakdown agar as an energy/ carbon source using agar slants for long-term storage of microbial cultures - correct answers - Slants have screw-cap that prevents the agar from drying out
- the tube can be tightly capped for relatively long term storage of an isolate with low risk of contamination
QUESTIONS 2025
using broth (liquid medium) tubes for growing microorganisms and generating cultures for experimental use - correct answers in broth a species may display motility and/or a characteristic pattern of association among individual cells, such as chains or clusters, that is not as obvious in agar microbe - correct answers a microorganism, especially a bacterium causing disease or fermentation bacterial media - correct answers allows us to isolate bacterium, identify morphology bacterial colony - correct answers site of bacterial growth; cluster of microorganism growing on agar surface bacterial culture - correct answers bacterial growth contamination - correct answers accidental introduction of infectious material sterilization - correct answers utilizing equipment such as a spirit lamp, bactincinerator, and an autoclave, we can sterilize and reuse Aseptic methods - correct answers in order to prevent contaminating microbes from entering cultures, we use aseptic methods to prevent such. The streak for isolation technique is the most common aseptic technique used to obtain discrete colonies of bacteria given in a mixed broth
QUESTIONS 2025
sterile swab - correct answers for collecting bacteria from surfaces labeling for media - correct answers label test tube on the top near the cap label the plate on the side with the following: lab sections, name of bacterial growth, own name reason for flaming the inoculating loop before and after each inoculation - correct answers to prevent cross contamination from microorganisms previously in contact, to kill unwanted bacteria for a new use and prevent cross contamination holding the test tube caps in the pink finger - correct answers to prevent the contamination of the test tube caps by unwanted microorganism from the table, from which the whole culture can be contaminated afterwards. Cooling the inoculating loop before obtaining the inoculum - correct answers the hot loop may create aerosols when it touches the culture. When the hot loop touches the liquid broth culture, it will cause some of the broth and bacteria to boil briefly, creating a bacteria-containing aerosol. these airborne bacteria could enter the student's respiratory tract or long on her skin. if you hear a hissing sound when you place the loop into the broth culture, you'll know you haven't cooled the loop sufficiently. hot inoculating loop will kill bacteria, which will be collected with it.
QUESTIONS 2025
Flaming the mouth of the test tube immediately after uncapping and again before recapping - correct answers this ensures that no microorganisms enter the mouth of the vessel to contaminate the culture or the medium. passing the moth of the bottle through a flame produces a convection current away from the opening, and helps prevent contamination. to eliminate the air which may be contaminated with unwanted organisms. Explain why an inoculating wire is used to inoculate an agar deep tube - correct answers the inoculum need to be drawn out from the bottom of the tube in a straight line, along the line of insertion why were the plated incubated at 25 degrees C rather than 37 C? - correct answers 25 Celsius is the optimum temperature for the bright red pigmentation produced by serratia marcescens, because the environment bacteria grows best at 25 C since that is closest to its natural environment temperature Some of your TSA plates show bacteria that produced orange-red pigmentation. Is it a pure culture? Explain. - correct answers orange and red did not show a pure culture it was from a mixed culture. we needed to make a pure culture In some of the plates, there is no red-orange pigmentation. does it mean your plate is contaminated? explain. - correct answers No it doesn't mean that there is contamination. it could just mean that you failed to inoculate the bacteria. Also, it could mean that the environment was wrong for the bacteria to grow. Discuss the cultural characteristics of microorganisms on agar plates, slants, and broth tubes - correct answers Broth: the bacterial growth checked by growth on the top or bottom, and turbidity when re-suspended.
QUESTIONS 2025
- used to obtain discrete colonies of bacteria given a mixed broth
- requires reduced quantity of inoculum that is diluted over an agar plate surface
- spreads loopful of cells far apart to separate colonies that can be transferred onto nutrient agar slants for generating pure cultures ubiquitous - correct answers microorganisms are everywhere Magnification - correct answers ability of microscope to enlarge an object depends upon the ocular lens and objective lens Resolution - correct answers ability to show two adjacent objects as discrete entities resolving power - correct answers is dependent upon wavelength of light used and numerical aperture par focal - correct answers specimen is in focus using 4x lens and the stage distance should remain the same. when objective lens of the microscope is changed, only a minimum of refocusing is necessary interpupillary distance - correct answers distance between eyes (pupils) and microscopes- use both eyes, distance between the centers of your two pupils to which the distance between the two eyepieces of the binoculae microscope must correspond
QUESTIONS 2025
Biological stain benzene - correct answers organic colorless solvent; chromosphore - chem group that imparts color to the benzene; auxchrome- has an ionization property, makes stain biological Simple staining purpose - correct answers observe morphology of cells Differential Staining purpose - correct answers observe cells on a deeper level (their cell wall, parts) principle of bacterial smears - correct answers to spread the bacteria in thin uniform layer for a better image under microscope principle of positive and negative staining - correct answers some cells are resistant to dyes so negative staining is used (background is dark, cells are colorless) Base and arms - correct answers for carrying microscope stage - correct answers flat platforms metal clips on stage - correct answers to clamp the glass slide in a flat horizontal position adjustment knobs - correct answers move the slide in different directions
QUESTIONS 2025
why is oil used with the 100x objective - correct answers because it has the same refractive index as glass and can eliminate the air in space between lens and slide What information is obtained from a simple stain? - correct answers the morphology (shape and arrangement) discuss the implications of capsules in bacterial diseases - correct answers they are sticky and they can attach to one another which will attract other bacteria to them. keep bacteria safe, exchanges the pathogenic abilities to cause disease can a negative stain show the internal structures of a bacterial cell? - correct answers no, they stain the background, leaving the cells colorless discuss the purpose for fixing bacterial cells on the slide - correct answers so that the bacteria will be killed and they will not be washed off the slide you spill coffee on your lab coat and the white fabric gets stained. is this biological stain or simply a compound that is capable of imparting color to the fabric? - correct answers this is a compound stain. a biological stain would be differential staining. no, it is not, because this stain is not used to observe the microorganisms. principle of differential staining - correct answers to identify the thickness of cell wall the chemical basis for gram staining - correct answers peptidoglycan
QUESTIONS 2025
primary stain name - correct answers crystal violet mordent stain name - correct answers iodine secondary/ counterstain name - correct answers safranin primary stain purpose - correct answers stains the cell mordent stain purpose - correct answers holds primary dye onto cell secondary/ counterstain purpose - correct answers recolors cells that loose stain through decolorization false positives - correct answers decolorizer is not performed long enough gram variability - correct answers bacteria that stain irregularly with gram's stain. neither gram + or - gram positive cell wall - correct answers thick. more peptidoglycan. lipid rich. is waxy so its impermeable
QUESTIONS 2025
decolorizing purpose - correct answers moves the primary dye from gram negative forgetting to refrigerate urine results in stain with great variability: intense purple to shades of red - correct answers cultures were old because of not being stored properly. cells become weak for the age so the cell wall not able to hold its structure differential stain - correct answers uses a series of reagents. used to distinguish one bacterial type from another simple stain - correct answers single basic dye. all cells stained the same color. no differentiation what is the medical importance for a gram stain - correct answers to find out what the cell wall structure of the cell and give an appropriate treatment is bacterial sporulation a reproductive process? - correct answers endospores is NOT a reproductive spore. no they form spores to survive harsh conditions staining method is used to visualize which aspect of bacterial anatomy? - correct answers the morphology and arrangement which one is more difficult to treat: an infection caused by gram negative or by gram positive bacteria? - correct answers gram negative harder. the peptidoglycan layer is so thin that the antibiotics will come out and it cannot kill the cell.
QUESTIONS 2025
2 types are mycobacterium and tuberculosis leprae 2 factors that increase resolution - correct answers short wavelengths and adjustment fine and focused knob.
