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Microbiology
| Question | Answer | ||
|---|---|---|---|
| These are the primary molecules making up the plasma membrane in cells _ | Lipids | Proteins | |
| Enzymes are made up of _ | Proteins | Carbohydrates | |
| What is a disulfide bond? | A covalent bond between two sulfur atoms in cysteine | A peptide bond linking amino acids in a chain | |
| What are the strongest and weakest bonds? | Strongest-covalent bond; weakest-hydrogen bond | Strongest-Ionic bond; weakest-covalent bond | |
| Which statement correctly describes the difference between a covalent bond and an ionic bond? | Covalent bonds form when electrons are shared; ionic bonds form when electrons are transferred | Ionic bonds involve sharing electrons; covalent bonds involve donating electrons | |
| What type of molecule contains glycerol? | Lipids | Carbohydrates | |
| Yeast is a fungus. T/F | True | False | |
| Which statement correctly explains how carbohydrates (like sugar) are converted into alcohol? | Yeast breaks down carbohydrates into ethanol and carbon dioxide during fermentation | Carbohydrates are converted into alcohol only when oxygen is present | |
| Oxygen is necessary for fermentation. T/F | False | True | |
| What is required in order for yeast to produce CO₂ & water? | Oxygen | Carbohydrates | |
| What is required in order for yeast to produce ethanol & CO₂? | No oxygen | ATP | |
| Lactic acid is necessary for cells to produce ATP during anaerobic respiration. T/F | True | False | |
| Which statement correctly describes DNA? | DNA is a nucleic acid made of nucleotides | DNA is a protein made of amino acids | |
| Which statement correctly describes a difference between prokaryotic and eukaryotic plasma membranes? | Eukaryotic membranes contain sterols like cholesterol; most prokaryotic membranes do not | Prokaryotic membranes contain cholesterol; eukaryotic membranes do not | |
| Both prokaryotic and eukaryotic membranes are phospholipid bilayers. T/F | True | False | |
| What is the role of cholesterol in the plasma membrane of eukaryotic/prokaryotic cells? | It prevents the membrane from becoming too rigid in cold temperatures and too fluid in warm temperatures | It removes phospholipids from the membrane to reduce movement | |
| Which statement correctly describes a difference between fungal and bacterial cell walls? | Fungal cell walls contain chitin; bacterial cell walls contain peptidoglycan | Bacterial cell walls contain chitin; fungal cell walls contain peptidoglycan | |
| Which statement correctly describes the relationship between prokaryotes and bacteria? | All bacteria are prokaryotes, but prokaryotes also include archaea | All prokaryotes are bacteria, and there are no other types of prokaryotes | |
| Which structural feature is characteristic of carbohydrates? | They typically follow a C:H:O ratio of 1:2:1 and often form ring structures | They contain nitrogenous bases attached to a sugar‑phosphate backbone | |
| Which structural feature distinguishes lipids from other organic molecules? | They consist of fatty acids attached to glycerol, forming long hydrophobic chains | They have many hydroxyl groups and form ring structures | |
| Which structural characteristic is unique to proteins? | They are made of amino acids linked by peptide bonds | They contain nitrogenous bases | |
| Which structural feature defines nucleic acids? | They are composed of nucleotides containing a phosphate, sugar, and nitrogenous base | They are made of amino acids with variable R‑groups | |
| Which structural feature distinguishes lipids from other organic molecules? | They contain long hydrocarbon chains with very few oxygen atoms | ||
| Which structural characteristic is unique to proteins? | They are made of amino acids with variable R‑groups | ||
| Which structural feature defines nucleic acids? | They contain nitrogenous bases attached to a sugar‑phosphate backbone | ||
| Which structural feature defines nucleic acids? | They contain a sugar‑phosphate backbone | ||
| Which structural feature defines nucleic acids? | They are composed of repeating nucleotide units | ||
| Which structural feature is characteristic of carbohydrates? | They consist of monosaccharides linked together | ||
| What type of molecule never contains a phosphate group? | Lipids | Carbohydrates | |
| Glucose & fructose are _ | Monosaccharides | Disaccharides | |
| Sucrose is a _ | Disaccharide | Monosaccharide | |
| Why would radioactive S³⁵ be found in Saccharomyces cerevisiae? | Because proteins contain sulfur‑bearing amino acids | Because DNA contains sulfur | |
| Why would radioactive P³² be found in Saccharomyces cerevisiae? | Because DNA and RNA have phosphate in their backbone | Because proteins contain large amounts of phosphate | |
| H₂SO₄ =acid/base | acid | base | |
| HF =acid/base | acid | base | |
| KH₂PO₄ =acid/base | acid | base | |
| MgSO₄ =salt/base | salt | base | |
| NaOH =acid/base | base | salt | |
| Maltose, Sucrose, Lactose (chemical formula) | C₁₂H₂₂O₁₁ | C₁₂H₂₃O₁₀ | |
| Two glucose molecules (chemical formula) | C₁₂H₂₄O₁₂ | C₁₂H₂₂O₁₁ | |
| Glucose (chemical formula) | C₆H₁₂O₆ | C₁₂H₂₂O₁₁ | |
| Lactic acid (chemical formula) | C₃H₆O₃ | C₁₂H₂₃O₁₀ | |
| What type of molecule never contains a phosphate group? | None of the above | Lipids | |
| Starch, dextran, glycogen, and cellulose are polymers of | Glucose | Amino acids | |
| Dark‑field microscopy is primarily used for | Observing live, unstained, thin organisms such as spirochetes | Viewing stained bacteria with high internal detail | |
| Which of the following microorganisms cannot be effectively observed using a dark-field microscope? | Thick pigmented fungi | Treponema pallidum | |
| DIC microscopy is best used for | Producing high‑contrast, 3D‑like images of live, unstained cells | Detecting capsules using India ink | |
| Phase‑contrast microscopy is especially useful for which type of specimen? | Live, unstained, transparent cells that need internal detail revealed | Spirochetes requiring a dark background for visibility | |
| Phase‑contrast microscopy is primarily used for | Observing live, unstained, transparent cells with visible internal structures | Producing 3D‑like images of eukaryotic cells | |
| When is a compound light microscope used? | Observing stained bacterial morphology | Viewing intracellular detail in a living cell | |
| A fluorescence microscope is most appropriately used when | You want to highlight specific cellular structures using fluorescent dyes | ||
| A scanning electron microscopy is used when | You want to observe surface topography at a very high magnification | ||
| An electron microscope is most appropriate used when you need to | Visualize viruses or ultrastructure below the limits of light microscopy | ||
| A dark field microscope is most appropriately used when you need to | Visualize thin, unstained, live organisms that are hard to see in brightfield | ||
| Which microscope uses phase shifts in light to visualize internal structures of living, unstained cells? | Phase contrast | Electron microscope | |
| What is a phase shift in light microscopy? | A change in the timing of a light wave after passing through a specimen | A change in the color of a light wave | |
| After the decolorizing agent is applied in a Gram stain, Gram-negative bacteria appear _ | Colorless | Purple | |
| Why do Gram-negative bacteria become colorless after the decolorizing step in a Gram stain? | Their thin peptidoglycan layer cannot retain the crystal-violet-iodine complex once the outer membrane is disrupted | Their thick peptidoglycan layer forces the dye out | |
| Which statement correctly explains why Gram-positive bacteria do not lose the crystal-violet-iodine complex during the decolorizing step? | Their thick peptidoglycan layer traps the crystal-violet-iodine complex, preventing it from being washed out | Their thin peptidoglycan layer allows the dye to escape easily | |
| Crystal violet is used during which part of the Gram stain procedure? | As the primary stain that initially colors all cells purple | As the counterstain | |
| What color do gram-positive stain? | Purple | Pink | |
| What color do gram-negative stain? | Pink | Purple | |
| Crystal violet is used during which part of the Gram stain procedure? | As the primary stain that initially colors all cells purple | As the counterstain | |
| Safranin is used during which step of the Gram stain procedure? | As the counterstain applied after decolorization | As the decolorizer | |
| What is the purpose of the mordant in the Gram stain? | To form a complex with crystal violet that enhances retention in Gram‑positive cells | To stain all cells purple | |
| Which statement correctly describes the role of the mordant (iodine) in the Gram stain? | It is applied to all cells but is retained better by Gram‑positive cells | It differentiates Gram‑positive from Gram‑negative cells | |
| What are mycoplasmas? | Bacteria that lack a cell wall | Bacteria with thick peptidoglycan layers | |
| Do gram-negative bacteria have a cell wall? | Yes, they have a thin peptidoglycan cell wall | Yes, they have a thick peptidoglycan cell wall | |
| Do all eukaryotes have the 9+2 microtubule arrangement? | No, only eukaryotes with cilia or flagella have the 9+2 structure | Yes, every eukaryotic cell has 9+2 microtubules | |
| What organism lives in extreme environments? | Archaea | Gram-negative bacteria | |
| Lysozyme is effective against what kind of bacteria? | Gram-positive | Gram-negative | |
| What is the primary function of a bacterial endospore? | Enable survival in extreme environmental conditions | Allow rapid bacterial reproduction | |
| Endospores are mainly (gram +/gram -) | Gram-positive | Gram-negative | |
| What is the primary role of a ribosome in the cell? | To synthesize proteins from mRNA templates | To replicate DNA during cell division | |
| Which statement correctly distinguishes DNA polymerase from a ribosome? | DNA polymerase synthesizes DNA, while ribosomes synthesize proteins | Ribosomes replicate DNA during cell division, while DNA polymerase builds proteins | |
| 0.9% NaCl & Lactated Ringer's solution are examples of | Isotonic solution | Hypertonic solution | Hypotonic solution |
| Which statement correctly distinguishes cilia from flagella in eukaryotic cells? | Cilia are short and numerous, while flagella are long and few | Cilia rotate like bacterial flagella, while eukaryotic flagella beat back and forth | |
| Which statement best describes a functional difference between cilia and flagella? | Cilia move fluid across a cell’s surface, while flagella propel the entire cell | Cilia rotate like propellers, while flagella beat in coordinated waves | |
| Which statement correctly describes the relationship between chloroplasts and thylakoids? | Thylakoids are membrane sacs inside chloroplasts where light-dependent reactions occur | Thylakoids store glucose produced during photosynthesis | |
| Which statement correctly describes the functional difference between cilia and pili? | Cilia allow eukaryotic cells to move or sweep materials, while pili allow bacteria to attach to surfaces or transfer DNA | Cilia are used by bacteria for conjugation, while pili help human cells move mucus | |
| Distilled water is | Hypotonic | Hypertonic | Isotonic |
| Which statement best describes the primary difference between the rough ER and smooth ER? | Rough ER synthesizes proteins, while smooth ER synthesizes lipids | Rough ER produces steroids, while smooth ER packages secretory vesicles | |
| What is the primary function of the Golgi complex in eukaryotic cells? | Modification, sorting, and packaging of proteins and lipids | Detoxification of drugs and storage of calcium ions | |
| Which feature correctly distinguishes archaea from bacteria? | Archaea have ether-linked membrane lipids, while bacteria have ester-linked lipids | Archaea are always extremophiles, while bacteria only live in mild environments | |
| Which statement correctly distinguishes fimbriae from pili? | Fimbriae are short and numerous, while pili are longer and fewer | Pili are found only in Gram-positive bacteria, while fimbriae are found only in Gram-negative bacteria | |
| Fimbriae and pili are mostly found in gram-negative bacteria. T/F | True | False | |
| What is catabolized in glycolysis? | Glucose | Glycogen | |
| What is the primary role of the Krebs cycle in aerobic respiration? | To generate NADH and FADH2 for the electron transport chain | To break down glucose into pyruvate | |
| What is the primary function of the pentose phosphate pathway? | To produce NADPH and ribose-5-phosphate | To oxidize fatty acids for energy | |
| Why are NADPH and ribose-5-phosphate essential products of the pentose phosphate pathway? | NADPH powers antioxidant defense and biosynthesis, while ribose-5-phosphate is required for nucleotide production | NADPH is used for ATP synthesis, and ribose-5-phosphate is used to make amino acids | |
| Why does the Entner–Doudoroff pathway provide certain bacteria with metabolic flexibility? | It allows glucose breakdown even when key glycolytic enzymes are missing | It replaces both glycolysis and the pentose phosphate pathway entirely | |
| Which organism is a classic example of a photoautotroph? | Chlamydomonas, Spirogyra | Chloroflexus, Heliobacterium | |
| Which organism is a photoheterotroph that uses light for energy but requires organic molecules for carbon? | Rhodospirillum, Rhodopseudomonas palustris | Cyanobacteria, Diatoms | |
| Which statement correctly describes alcohol use as a carbon source in phototrophic organisms? | Photoautotrophs cannot use alcohols for carbon, but some photoheterotrophs can | Photoautotrophs can use alcohols for carbon, but photoheterotrophs cannot | |
| Which characteristic best defines spirochetes? | They are spiral-shaped bacteria with internal flagella | They are rod-shaped bacteria with external flagella | |
| Why does the pH of a lipid-rich medium decrease when bacteria produce lipase? | Lipase releases fatty acids that donate H⁺ ions | Lipase converts lipids into alkaline compounds | |
| What is the primary function of an allosteric inhibitor? | It binds to a regulatory site and changes the enzyme’s shape, reducing activity | It increases the enzyme’s affinity for its substrate | |
| Why are allosteric inhibitors important in cellular metabolism? | They allow cells to regulate enzyme activity based on energy needs | They replace ATP as the main energy source in the cell | |
| Which option best describes a key difference between quinones and cytochromes in the electron transport chain? | Quinones are lipid‑soluble mobile carriers, while cytochromes are protein‑bound heme carriers | Cytochromes carry both electrons and protons, while quinones carry only electrons | |
| Which option describes a similarity between quinones and cytochromes? | Both participate in electron transfer within the electron transport chain | Both carry protons across the membrane | |
| What is the primary purpose of agar in microbiology? | Act as a solidifying agent for culture media | Provide nutrients for bacterial growth | |
| Methylene blue is primarily used to | Provide a simple stain to visualize bacterial morphology | Stain acid‑fast organisms | |
| What stain is used to detect endospores? | Malachite green | Methylene blue | |
| What stain is used to detect acid-fast organisms? | Carbol fuchsin | Methylene blue | |
| What is used to differentiate between gram-positive and gram-negative bacteria? | Alcohol/acetone | Iodine | |
| Crystal violet stains which group of bacteria after the iodine step? | Gram‑positive bacteria | Gram‑negative bacteria | |
| Carbol fuchsin is used to identify organisms with | Mycolic acids in their cell walls | Thick peptidoglycan | |
| Which statement correctly distinguishes chemoautotrophs from chemoheterotrophs? | Chemoautotrophs use inorganic chemicals for energy and CO₂ for carbon; chemoheterotrophs use organic molecules for both | Chemoautotrophs use CO₂ for energy; chemoheterotrophs use inorganic chemicals for energy | |
| Which statement correctly describes the difference between organic and inorganic carbon? | Organic carbon usually contains C–H bonds, while inorganic carbon does not | Organic carbon comes from nonliving sources, while inorganic carbon comes from living organisms | |
| Which of the following is an example of inorganic carbon? | Carbon dioxide (CO₂) | Amino acids | |
| Which carbon source would a chemoautotroph most likely use? | Carbon dioxide (CO₂) | Glucose | |
| Which statement correctly describes the origin of organic vs inorganic carbon? | Organic carbon comes from living or once‑living organisms, while inorganic carbon comes from nonliving sources like air, water, and minerals | Organic carbon always lacks hydrogen, while inorganic carbon always contains hydrogen | |
| Which of the following is TRUE of nitrogen‑fixing chemoautotrophs? | They use CO₂ as their carbon source and convert N₂ gas into ammonia | They obtain energy from organic molecules like glucose | |
| Which of the following best describes inoculation in microbiology? | Introducing microorganisms into a sterile medium | Allowing microbes to grow at a specific temperature | |
| Direct microscopic counts are most useful when | You need an immediate total cell count, including live and dead cells | You want the most accurate measurement of viable bacteria | |
| Viable cell counts measure | Only living cells capable of forming colonies | All cells present, including dead ones | |
| Standard plate counts are most appropriate when | You need to determine the number of viable, culturable bacteria in a sample | You need a rapid total cell count including live and dead cells | |
| The most probable number (MPN) method is most appropriate when | The sample is expected to have very low numbers of bacteria, such as coliforms in water | The sample is too concentrated to count microscopically | |
| What kind of media is used in MPN? | liquid | agar plates | |
| Rapid total counts are done with _ | Direct microscopic counts | Standard plate counts | |
| Most probable number method is done with high/low density samples | High | Low | |
| Serial dilution plate counts are primarily used when | The bacterial concentration is too high to count directly on a plate | You need a rapid estimate of cell numbers without incubation | |
| The MPN method is typically used only with liquid media because | MPN requires observing growth patterns in broth tubes | Agar interferes with colony formation | |
| Which statement best describes what an assay is? | A laboratory test that measures one specific substance or activity in a sample | A test that measures all components of a biological sample | |
| Which statement correctly distinguishes standard plate counts from glucose‑based growth measurement? | Standard plate counts give viable cell numbers at one time point, while glucose consumption measures metabolic activity continuously in liquid media | Standard plate counts measure glucose levels on agar plates, while glucose consumption measures colony size | |
| Turbidity is primarily used to measure microbial growth when | You need a rapid, continuous estimate of cell density in a liquid culture | You want to count viable colonies after incubation | |
| What does the term obligate mean when describing microbial oxygen requirements? | The organism either must have oxygen or must avoid oxygen, with no flexibility | The organism can tolerate oxygen but never uses it | |
| What does facultative mean in microbial oxygen tolerance? | The organism prefers oxygen but can grow without it | The organism tolerates oxygen but never uses it | |
| What does aerotolerant mean in microbiology? | The organism does not use oxygen but can survive in its presence | The organism prefers oxygen but can grow without it | |
| Which reaction is catalyzed by catalase? | 2H₂O₂ →2H₂O + O₂ | O₂¯ + O₂¯→H₂O₂ | |
| Which reaction is catalyzed by superoxide dismutase? | O₂¯+O₂¯+2H⁺→2H₂O₂ + O₂ | 2H₂O₂+NADH→2H₂O | |
| Which reaction is catalyzed by oxidase? | 4cyt c (reduced) + O₂ + 4H⁺→ 4cyt c (oxidized) + 2H₂O | 2H₂O₂ + organic donor → 2H₂O | |
| Which reaction is catalyzed by peroxidase? | H₂O₂ + electron donor → 2H₂O | 2O₂¯ + 2H⁺→2H₂O₂ + O₂ | |
| What is the growth range for psychrophiles? | 0–20°C | 4–30°C | |
| What is the growth range for psychotrophs? | 4–30°C | 20–45°C | |
| What is the growth range for mesophiles? | 20–45°C | 4–30°C | |
| What is the growth range for thermophiles? | 50–80°C | 20–45°C | |
| What is the growth range for hyperthermophiles? | 80–110°C | 50–80°C | |
| Which type of organism is killed by exposure to oxygen? | Obligate anaerobe | Obligate aerobe | |
| Which type of organism requires oxygen but only at levels lower than those found in the atmosphere? | Microaerophile | Aerotolerant anaerobe | |
| Which type of organism does not use oxygen for respiration but can survive in its presence? | Aerotolerant anaerobe | Facultative anaerobe | |
| Where do gram-negative bacteria most commonly live? | Fresh water and mucous membranes | Salty skin surfaces | |
| Gram-positive bacteria are most commonly associated with which type of environment? | High salt, dry environments such as skin | Freshwater and mucous membranes | |
| Which statement correctly describes the difference between an enrichment medium and a selective medium? | Enrichment medium boosts the desired microbe; selective medium inhibits unwanted microbes | Enrichment medium inhibits unwanted microbes; selective medium boosts desired microbes | |
| What is the primary purpose of a differential medium? | To distinguish organisms based on visible biochemical reactions | To inhibit unwanted microbes | |
| Which statement correctly describes the difference between the objective lens and the ocular lens? | The objective lens produces the initial magnified image, while the ocular lens magnifies that image further | Both lenses perform the same function but are located in different parts of the microscope | |
| What is the purpose of the oil immersion objective on a microscope? | To prevent light from scattering and improve resolution at high magnification | To increase contrast by staining the specimen | |
| What primary stain is used in the scaeffer-fulton endospore staining method? | Malachite green | Carbolfuchsin | |
| In the Dorner method what color endospores appear after staining? | Red | Green | |
| Which situation most strongly indicates you should use the Scaeffer-Fulton spore stain? | You need a routine fast spore stain using malachite green | You need to preserve cell morphology without heat fixing | |
| Which clue in a staining protocol tells you the Dorner method is required? | Carbolfuchsin & nigrosin are both included | Malachite green is the primary dye | |
| Which term describes a metabolically active, growing bacterial cell? | Vegetative cell | Germinated cell | |
| Which structure is highly resistant and metabolically inactive? | Spore | Capsule | |
| Sporogenesis occurs when | Conditions become unfavorable | Conditions become favorable | |
| A “free spore” refers to | A spore released from a degenerating vegetative cell | A spore undergoing germination | |
| What is a spore called undergoing germination | Vegetative Cell | ||
| An endospore refers to | A spore still inside the vegetative cell | ||
| What structure is produced during sporogenesis? | A highly resistant endospore | A metabolically active vegetative cell | |
| What makes mycobacteria uniquely different from most other bacterial organisms? | They have a thick, waxy cell wall rich in mycolic acids | They are Gram‑negative rods with an outer membrane | |
| Which genera are known for forming spores? | Clostridium and Bacillus | Escherichia and Salmonella | |
| Spores are resistant to all of the following EXCEPT | Mild detergents | Radiation | |
| Which term describes the process of a spore becoming a vegetative cell again? | Germination | Sporogenesis | |
| Spores resist staining because | Their spore coats are impervious | They dissolve in stain | |
| Louis Pasteur is best known for which major scientific contribution? | Development of the germ theory of disease | Discovery of penicillin | |
| What was the purpose of Pasteur’s swan‑neck flask experiment? | To disprove spontaneous generation | To test antibiotic resistance | |
| What is lysogeny? | The integration of phage DNA into the bacterial chromosome, forming a dormant prophage | The process where a phage immediately replicates and lyses the bacterial cell | |
| Which factor most strongly determines whether a temperate phage enters the lysogenic cycle instead of the lytic cycle? | High levels of CI repressor and a healthy, nutrient‑rich host cell | The presence of cytochromes in the bacterial membrane | |
| What is a cell‑free filtrate? | A filtered extract from tumor tissue that contains viruses but no cells | A solution containing intact tumor cells used to study cancer growth | |
| Which statement best describes an oncogene? | A mutated or overactive proto‑oncogene that drives uncontrolled cell growth | A viral gene that always causes cancer | |
| What is the primary function of lysozymes? | Hydrolyzing peptidoglycan in bacterial cell walls | Digesting worn-out organelles inside the cell | |
| What is the purpose of dna dependent dna polymerase? | It is the enzyme that builds new DNA strands using an existing DNA strand as the template | Transcribing DNA into RNA during gene expression | |
| What is the purpose of RNA polymerase? | Synthesizing RNA from an RNA template | Converting RNA into DNA during viral replication | |
| What is the primary function of histones in eukaryotic cells? | Packaging DNA into nucleosomes to organize and compact the genome | Synthesizing proteins during translation | |
| How do histones help eukaryotic cells? | By organizing and compacting DNA so it fits inside the nucleus | By synthesizing new DNA during replication | |
| ATP synthase is best described as | An enzyme that produces ATP using a proton gradient | An enzyme that breaks down ATP into ADP | |
| Which of the following best describes a bacteriostatic drug? | It prevents bacteria from growing and dividing | It disrupts the bacterial plasma membrane | |
| Folic acid synthesis in bacteria is required for the production of | DNA, RNA, and certain amino acids | Ribosomal proteins | |
| Which of the following drugs inhibits protein synthesis? | Streptomycin | Polymyxin B | |
| Niclosamide is best described as | An anthelmintic that blocks ATP production in tapeworms | An antibiotic that inhibits cell‑wall synthesis | |
| Osmotic pressure is best defined as | The force of water moving toward higher solute concentration | The movement of solutes across a membrane | |
| Which statement correctly explains why nucleic acid synthesis inhibitors work against bacteria? | They inhibit bacterial DNA gyrase or RNA polymerase, stopping replication or transcription | They destroy bacterial ribosomes, stopping protein synthesis | |
| Which organisms do not have true histones? | Bacteria | Fungi | |
| Which statement correctly distinguishes DNA replication from protein synthesis? | DNA replication copies genetic material, while protein synthesis builds proteins | DNA replication builds proteins, while protein synthesis copies the chromosome | |
| Which statement correctly describes how yeast and bacteria reproduce? | Yeast reproduce by budding, while bacteria reproduce by binary fission | Yeast reproduce by binary fission, while bacteria reproduce by budding | |
| What stain is commonly used to visualize fungi? | Lactophenol cotton blue | India ink | |
| Which of the following best defines a substrate? | A molecule that the enzyme acts upon | The site on an enzyme where reactions occur | |
| What characteristic do most organic molecules share? | They contain carbon-hydrogen bonds | They contain oxygen | |
| Which statement correctly distinguishes sporulation from germination in bacteria? | Sporulation is the formation of an endospore from a vegetative cell, while germination is the development of an endospore into a vegetative cell. | Sporulation is the conversion of an endospore into a vegetative cell, while germination is the formation of an endospore. | |
| Which of the following best distinguishes a free-living protozoan from a parasitic protozoan? | Free-living protozoa obtain nutrients from their environment, whereas parasitic protozoa obtain nutrients from a host organism | Free-living protozoa lack a nucleus, whereas parasitic protozoa possess a nucleus | |
| Which feature is characteristic of nematodes but not platyhelminthes? | Complete digestive tract with mouth and anus | Triploblastic body plan | |
| A tapeworm lacks a digestive tract because | It absorbs pre-digested nutrients from its host | It cannot absorb nutrients | |
| Which group is most likely to grow in an acidic environment with a pH of 4.0? | Yeasts and molds | Endospore-forming bacteria only | |
| Which statement is correct? | Both yeasts and molds belong to the kingdom Fungi | asts and molds are different kingdoms | |
| Which of the following best describes a tincture? | A chemical dissolved in alcohol | A chemical dissolved in oil | |
| Which of the following is a unicellular organism? | Amoeba | Mushroom | |
| Which protozoan group moves primarily by means of pseudopodia (false feet)? | Sarcodina | Mastigophora | |
| Which locomotory structure is characteristic of members of the class Sarcodinia? | Pseudopodia | Spores | |
| The movement of Trypanosoma is primarily accomplished by | Flagella | Cilia | |
| Which protozoan uses numerous short-hair like structures for locomotion? | Paramecium | Amoeba proteus | |
| Which of the following protozoa is classified as a sporozoan? | Plasmodium spp. | Paramecium caudatum | |
| The movement of Amoeba proteus is primarily accomplished by | Pseudopodia | ||
| The movement of Entamoeba histolytica is primarily accomplished by | Pseudopodia | ||
| Coenocytic hyphae are best described as | Hyphae with no cross‑walls and many nuclei | Hyphae divided by many septa | |
| The primary advantage of septate hyphae is that they | Limit cytoplasmic loss when the hypha is damaged | Allow photosynthesis | |
| Which fungal phylum is characterized by coencytic (non-septate) hyphae? | Zygomycota | Basidomycota | |
| Which of the following fungi does not typically possess true hyphae? | Saccharomyces | Aspergillus | |
| Which characteristic is most typical of the phylum Ascomycota? | Production of ascospores within asci | Presence of coenocytic hyphae and zygospores | |
| What is a major advantage of coenocytic (non-septate) hyphae in fungi such as Rhizopus? | They allow rapid movement of cytoplasm and nutrients throughout the hyphae | They prevent the loss of cytoplasm after injury | |
| Which of the following characteristics is most commonly associated with Rhizopus? | Produces zygospores and has coencytic (non-septate) hyphae | Produces ascospores within asci and has septate hyphae | |
| Ascospores are best described as | Sexual spores produced inside a sac by Ascomycete fungi | Asexual spores produced on specialized hyphae | |
| What statement correctly distinguishes ascospores from conidia? | Ascospores are produced in asci during sexual reproduction, whereas conidia are asexual spores produced externally on hyphae | Ascospores are asexual spores, whereas conidia are sexual spores | |
| An Aspergillus colony growing on a nutrient-rich substrate is most likely to produce | Conidia | Ascospores | |
| Why might a fungus switch from asexual to sexual reproduction? | To increase genetic variation and adaptability | To produce genetically identical offspring more rapidly | |
| Which statement correctly distinguishes an oncogene from an oncoprotein? | An oncogene is DNA that encodes an oncoprotein | An oncogene is a protein, whereas an oncoprotein is a gene | |
| A cell becomes infected with an oncogenic virus. Which sequence correctly describes how viral DNA can contribute to cancer development? | Viral DNA→Viral proteins→Disruption of normal cell-cycle control→Increased risk of cancer | Viral DNA→Oncoproteins→Host cell reads viral DNA→Cancer | |
| What are hyphae? | Thread-like filaments that make up the body of a fungus | The fruiting bodies of fungus | |
| A patient is infected with HIV, a retrovirus. Why is the enzyme reverse transcriptase essential for the viral life cycle? | It converts viral RNA into DNA, allowing the viral genetic material to integrate into the host genome | It converts viral proteins into DNA, allowing viral replication | |
| Which of the following best describes a latent viral infection? | The virus remains dormant within host cells, with little or no production of new virus particles until reactivation occurs | The virus is destroyed by the immune system and no longer exists in the body | |
| Why can a latent virus persist in the body for years? | The virus enters a genetically programmed dormant state in which most viral genes are inactive | The virus stops containing genetic mate | |
| Which of the following best distinguishes a provirus from a prophage? | A provirus is viral DNA integrated into a eukaryotic host genome, whereas a prophage is viral DNA integrated into a bacterial genome | A provirus is made of protein, whereas a prophage is made of DNA | |
| What is the primary function of a viral capsid? | To protect the viral nucleic acid and aid in host-cell infection | To perform protein synthesis | |
| Which of the following best describes a virion? | The complete infectious virus particle outside a host cell | ||
| During the eclipse period of viral replication, which statement is correct? | Viral nucleic acid and proteins are being synthesized, but complete virions have not yet been assembled | Large numbers of complete virions are present inside the host cell | |
| Which of the following best defines a genome? | The complete set of genetic material in an organism or virus | A single protein produced by a gene | |
| Which statement best explains catabolic enzymes and why viruses do not possess them? | Catabolic enzymes break down molecules to release energy, and viruses lack them because viruses do not perform metabolism | Catabolic enzymes build macromolecules, and viruses lack them because they rely on host ribosomes | |
| Which statement best describes the protein coat of a virus and its primary function? | The protein coat protects the viral genome and assists in attaching to and entering host cells | The protein coat allows viruses to perform metabolism and synthesize their own proteins | |
| Which statement best explains the purpose of the lipid envelope in enveloped viruses? | The lipid envelope allows the virus to fuse with host cell membranes and helps it evade the immune system | The lipid envelope strengthens the capsid and prevents cell lysis during viral release | |
| Why is RNA primarily single‑stranded in biological systems? | Because single‑stranded RNA can fold into complex 3D shapes that allow it to function in catalysis, translation, and regulation | Because single‑stranded RNA is more stable and ideal for long‑term genetic storage | |
| Which statement best describes non‑enveloped viruses? | They lack a lipid envelope and are therefore highly resistant to heat, drying, acids, and detergents | They cannot survive outside the body because their capsid is unstable without an envelope | |
| Which statement best explains why viruses are not considered alive? | They lack cellular structure and cannot carry out metabolism independently | They only infect animals, not plants or bacteria | |
| Which feature is characteristic of picornaviruses? | They are small, non‑enveloped, positive‑sense single‑stranded RNA viruses | They are large, enveloped, double‑stranded RNA viruses | |
| Which statement correctly describes positive‑sense single‑stranded RNA viruses? | Their RNA genome can function directly as mRNA upon entering the host cell | Their RNA cannot be translated until it is converted into negative‑sense RNA | |
| Why do positive‑sense RNA viruses replicate more quickly than other RNA viruses? | Their RNA genome can be directly translated by host ribosomes without prior modification | They do not require any polymerase enzymes to replicate their genome | |
| Which characteristic correctly describes togaviruses? | They are enveloped, positive‑sense RNA viruses that replicate in the cytoplasm | They are non‑enveloped viruses that replicate in the nucleus | |
| Which statement correctly describes the old “papovavirus” group? | It referred to non‑enveloped, circular double‑stranded DNA viruses including papillomaviruses and polyomaviruses | It described segmented DNA viruses that replicate in the cytoplasm | |
| Rubella and chikungunya are what kind of viruses? | Togaviruses | Picornavirus | |
| Which feature is characteristic of retroviruses? | They carry reverse transcriptase, allowing conversion of RNA into DNA before integration | They do not integrate into the host genome during replication | |
| Which DNA virus family replicates in the cytoplasm instead of the nucleus? | Poxviridae | Adenoviridae | |
| Which best explains why most DNA viruses must replicate in the nucleus? | They require host DNA and RNA polymerases that are located in the nucleus | They must integrate into the host genome before replication | |
| Which feature best identifies a virus as a DNA virus? | Its genome consists of deoxyribonucleic acid rather than ribonucleic acid | It must integrate into the host genome to replicate | |
| Which characteristic is true of all human herpesviruses? | They establish lifelong latent infections within specific host cells | They are non‑enveloped viruses that cause only acute infections | |
| Which statement correctly describes a negative‑sense RNA virus? | It must carry an RNA‑dependent RNA polymerase in the virion to make positive‑sense RNA | They contain negative‑sense DNA genomes | |
| Which statement about negative‑sense RNA viruses is true? | They must carry an RNA‑dependent RNA polymerase to generate readable RNA | They rely entirely on host enzymes for genome replication | |
| Which statement best describes lysozyme? | An antimicrobial enzyme that hydrolyzes peptidoglycan in bacterial cell walls | A protein that neutralizes toxins by binding to lipopolysaccharide | |
| Which statement best describes a prion? | A misfolded protein that induces other proteins to misfold and contains no nucleic acids | A slow‑growing bacterium that resists antibiotics | |
| Why can’t a virus contain both DNA and RNA? | Because viruses are defined by having only one type of nucleic acid | Because DNA and RNA cannot coexist inside a cell | |
| Which of the following describes the capsid of a virus? | The protein coat that surrounds and protects the viral nucleic acid | The lipid envelope surrounding some viruses | |
| Which organisms produce catalase? | Aerobes & facultative anaerobes | Aerotolerant anaerobes & obligate anaerobes | |
| What is a zygospore? | A sexual spore formed by fusion of two hyphae in Zygomycetes | An asexual conidium formed on specialized hyphae | |
| Which organisms grow in acidic and alkaline environments? | Lactobacillus grows in acidic environments; Bacillus species grow in alkaline environments | Streptococcus grows in alkaline environments; Rhizopus grows in acidic environments | |
| Why are gram‑positive bacteria most susceptible to penicillin during the log phase? | Because penicillin targets cell wall synthesis, which is highest during the log phase | Because penicillin works best when bacteria are not dividing | |
| Which types of chemical cleaners are safe to use on human skin, and which are not? | Antiseptics are safe for skin; disinfectants are for non‑living surfaces | Disinfectants are safe for skin; antiseptics are only for metal instruments | |
| What are acid‑anionic detergents primarily used for? | Sanitizing dairy and food‑processing equipment by removing residues and killing bacteria | Sterilizing surgical instruments by killing endospores | |
| What is the primary use of benzoic acid in microbiology and food science? | Preserving acidic foods by inhibiting the growth of molds and yeasts | Neutralizing alkaline spills in the laboratory | |
| When is it best to use benzoic acid versus sorbic acid as food preservatives? | Benzoic acid is best in highly acidic foods; sorbic acid works well in mildly acidic to near‑neutral foods | Benzoic acid is best in mildly acidic foods; sorbic acid only works below pH 4 | |
| Which of the following diseases is caused by a prion? | Creutzfeldt-Jakob disease (CJD) | Tetanus | |
| Which of the following statements is correct regarding scrapie and bovine spongiform encephalopathy (BSE)? | Scrapie affects sheep and goats, while BSE affects cattle; both are prion diseases | Scrapie is caused by a virus, while BSE is caused by a prion | |
| Which of the following best defines encephalopathy? | A disease or dysfunction of the brain that impairs normal brain function | Inflammation of the meninges surrounding the brain and spinal cord | |
| What is the primary mechanism by which alcohols such as ethanol and isopropanol kill microorganisms? | Denaturation of proteins and disruption of lipid membranes | Inhibition of DNA replication by binding DNA gyrase | |
| Which of the following best describes the antimicrobial mechanism of action of chlorine compounds such as sodium hypochlorite (bleach)? | Oxidation of cellular components, including proteins, membranes, and nucleic acids | Denaturation of proteins only, with no effect on membranes | |
| A microbiology student is testing the effectiveness of a disinfectant against Mycobacterium smegmatis and Bacillus cereus. Which statement best explains why both organisms may be more resistant than typical vegetative bacteria? | M. smegmatis has a waxy mycolic acid cell wall, and B. cereus can form resistant endospores | M. smegmatis produces endospores, and B. cereus has a mycolic acid cell wall | |
| Which of the following best describes the antimicrobial mechanism of action of hydrogen peroxide (H₂O₂)? | It produces reactive oxygen species that oxidize and damage cellular components | It denatures proteins and dissolves lipid membranes | |
| Hydrogen peroxide kills microorganisms primarily through the production of reactive oxygen species (ROS). Which of the following cellular components can be damaged by ROS? | DNA, proteins, and cell membranes | DNA only | |
| A bacterial infection is being treated with ciprofloxacin. Which mechanism of action best explains how this antibiotic inhibits bacterial growth? | Inhibits DNA replication by targeting DNA gyrase | Binds the 30S ribosomal subunit and blocks protein synthesis | |
| Which of the following antibiotics kills bacteria by disrupting the cell membrane causing leakage of cellular contents? | Polymyxin B | Tetracycline | |
| Which of the following correctly compares the mechanisms of tetracyclines and macrolides? | Tetracyclines bind the 30S ribosomal subunit whereas macrolides bind the 50S ribosomal subunit | Both bind the 30S ribosomal subunit and block tRNA attachment | |
| Why can aerotolerant anaerobes survive in the presence of oxygen? | They possess enzymes that detoxify reactive oxygen species | They use oxygen for aerobic respiration | |
| Which of the following best describes s. aureus? | Facultative anaerobe commonly found on the skin and in the nose | Obligate anaerobe found primarily in soil | |
| A bacterium grows primarily at the top of a thioglycolate tube and is part of the normal skin flora. Which organism is most likely? | Corynebacterium xerosis | Clostridium sporogenes | |
| Which statement about enterococcus faecalis is true? | It is an aerotolerant anaerobe commonly found in the intestinal tract | It forms endospores that allow survival in high oxygen environments | |
| A bacterium grows only at the bottom of a thioglycolate tube and is commonly found in soil. Which organism is it? | Clostridium sporgenes | Enterococcus faecalis | |
| A mold is isolated from soil. It grows only where oxygen is present and fails to grow in anaerobic conditions. Which organism is most likely? | Aspergillus niger | Saccharomyces cerevisiae | |
| Which organism can perform aerobic respiration when oxygen is available but can switch to fermentation when oxygen is absent? | Saccharomyces cerevisiae | Aspergillus niger | |
| Which of the following organisms would be most likely to thrive in a salt evaporation pond? | Halophile | Acidophile | |
| Helicobacter pylori is able to survive in the highly acidic environment of the stomach primarily because it: | Produces the enzyme urease which helps neutralize acid around the bacterium | Uses oxygen to convert stomach acid into water | |
| A microbiologist isolates a bacterium from a highly alkaline lake with a pH of 10.5. The organism grows best under conditions and poorly at neutral pH. Which classification best describes this organism? | Alkaliphile | Acidophile | |
| Which type of RNA carries the genetic code from DNA to the ribosome? | mRNA | tRNA | |
| Which cellular structure directly synthesizes proteins from the genetic information carried by mRNA? | Ribosome | Golgi apparatus | |
| Which process occurs directly in the thylakoid membranes of chloroplasts? | Light-dependent reactions | Carbon fixation in the stroma | |
| Which RNA virus is directly associated with adult T-cell leukemia/lymphoma? | HTLV-1 | HPV | |
| Which of the following viruses is a DNA virus? | Hepatitis B virus (HBV) | Hepatitis C virus (HCV) | |
| Almost all hepatitis viruses are RNA viruses except one. Which hepatitis virus is a DNA virus? | Hepatitis B virus (HBV) | Hepatitis A virus (HAV) | |
| Which DNA virus is most strongly associated with cervical cancer because its viral proteins inactivate tumor suppressor proteins p53 and Rb? | Human papillomavirus (HPV) | Human T-cell leukemia type 1 (HTLV-1) | |
| Which RNA virus can directly cause adult T-cell leukemia/lymphoma by integrating into host DNA and promoting uncontrolled T-cell proliferation? | Human T-cell leukemia type 1 (HTLV-1) | Epstein-Barr virus (EBV) | |
| Which of the following statements correctly describes how a fungal toxin can cause disease in humans? | Aspergills flavus produces aflatoxin, which damages DNA in liver cells and increases the risk of liver cancer | Aspergillus flavus produces aflatoxin, which stimulates histamine release and causes itching | |
| A bacteriophage infects a bacterium and integrates its DNA into the bacterial chromosome without immediately producing new phage particles. This stage is known as | Lysogenic cycle | Biosynthesis | |
| A bacteriophage remains dormant as a prophage in a bacterial chromosome and later enters the lytic cycle. This transition is called | Induction | Lysis | |
| During the assembly (maturation) stage of the lytic cycle, what occurs? | New phage DNA and proteins are assembled into complete viruses | Viral DNA integrates into the host chromosome | |
| What is the major difference between the lytic and lysogenic cycles? | The lytic cycle immediately produces new viruses and destroys the host cell whereas the lysogenic cycle incorporates viral DNA in the host genome without immediately killing the cell | The lytic cycle produces a prophage whereas the lysogenic cycle causes immediate lysis | |
| Lysozyme is commonly found in | Tears and saliva | Red blood cells | |
| Which of the following diseases is caused by a herpesvirus? | Chickenpox | Polio | |
| Which of the following viruses is most likely to establish latency in the body? | Varicella-zoster virus (VZV) | Hepatitis A virus | |
| Which virus is most commonly associated with outbreaks of acute gastroenteritis on cruise ships? | Norovirus | Epstein-Barr virus | |
| Which of the following is the best description of a catabolic enzyme? | An enzyme that breaks large molecules into smaller molecules | An enzyme that builds proteins from amino acids | |
| Bacterial DNA is transferred from one bacterium to another by a bacteriophage. This process is called | Transduction | Conjugation | |
| A bacterium acquires an antibiotic-resistance gene from DNA released by a dead bacterium. The acquired DNA is best described as | Naked DNA | Viral DNA | |
| Which of the following is true regarding viral genomes? | Viruses contain either DNA or RNA | Viruses contain both DNA and RNA | |
| Which of the following viruses contains double-stranded RNA? | Rotavirus | Rabies | |
| Which of the following viruses is the only common DNA virus that contains single-stranded DNA (ssDNA)? | Parvovirus | Herpes virus | |
| Which statement best describes the difference between a viral spike and a bacterial pilus? | A spike helps a virus attach to and enter a host cell, whereas a pilus helps a bacterium attach to surfaces or other cells | Both function primarily to inject genetic material into host cells | |
| A bacteriophage binds to receptors on the surface of a bacterial cell. This step is called | Adsorption | Transduction | |
| Which of the following best describes a viroid? | A small infectious RNA molecule that lacks a protein coat | A bacterium without a cell wall | |
| A fungus growing on dead bread is best described as | Saprophytic | Pathogenic | |
| The thread-like filaments that make up the body of a mold are called | Hyphae | Mycelia | |
| What is mycelia? | A mass of hyphae | Long thread-like structures that make up molds | |
| Which of the following best describes a fomite? | A contaminated nonliving object that can transmit pathogens | A living organism that transmits disease between hosts | |
| Which scenario best describes a focal infection? | A tooth infection spreads and causes an infection in the heart valves | An infected cut remains confined to the finger | |
| A patient develops a small bacterial infection on the skin of the leg. The infection remains confined to the area and does not spread. Which type of infection is this? | Local infection control | Focal infection | |
| A bacterium secretes a protein that kills closely related bacterial species competing for nutrients. This protein is most likely a | Bacteriocin | Endospore | |
| Most bacteria that cause disease in humans are classified as | Neutrophiles | Halophiles | |
| A patient with influenza tells the physician, "I have a headache and feel very tired." The physician records a temperature of 102℉ | Headache is a symptom and fever is a sign | Headache is a sign and fever is a symptom | |
| A bacterial infection spreads from a wound into the bloodstream, where the bacteria multiply. This condition is called | Septicemia | Systemic infection | |
| What was the most important contribution of Robert Koch to microbiology? | He demonstrated that specific microorganisms cause specific diseases | He discovered antibiotics | |
| What was the most important contribution of Alexander Fleming to microbiology? | He discovered antibiotics | He demonstrated that specific microorganisms cause specific diseases | |
| A bacterium lives on human skin and obtains nutrients and a place to live. The host is neither helped nor harmed. This relationship is best described as | Commensalism | Mutualism | |
| What disease does Varicella-zoster virus (VZV) cause? | Chickenpox | Measles | |
| A disease is consistently present in a region at relatively stable levels year after year. This disease is best described as | Endemic | Epidemic | |
| A city typically reports about 20 cases of measles each year. During one year, the number of cases suddenly rises to 1500. This increase is best described as | Epidemic | Endemic | |
| Which bacterial enzyme is known as the 'spreading factor' because it breaks down connective tissue and allows bacteria to spread between cells? | Hyaluronidase | DNase | |
| A bacteriophage infects a bacterium and incorporates its DNA into the bacterial chromosome without immediately killing the bacterium. This bacteriophage is best described as | Temperate phage | Virulent phage | |
| A bacterium acquires a toxin gene from a bacteriophage. This is an example of | Horizontal gene transfer | Vertical gene transfer | |
| A bacterium divides by binary fission passing a newly acquired antibiotic-resistance gene to its daughter cells. This is an example of | Vertical gene transfer | Horizontal gene transfer | |
| A bacteriophage inserts a toxin gene into a bacterium. The bacterium subsequently gains the ability to produce the toxin. This is an example of | Lysogenic conversion | Transformation | |
| A bacteriophage transfers an antibiotic-resistance gene from one bacterium to another. This is an example of | Transduction | Lysogenic conversion | |
| A bacterium acquires an antibiotic-resistance gene by absorbing free DNA released from a dead bacterium in its environment. This process is called | Transformation | Transduction | |
| A bacterium transfers an antibiotic-resistance plasmid directly to another bacterium through a sex pilus. This process is called | Conjugation | Transduction | |
| A bacterium contains a small circular DNA molecule that is independent of the chromosome and carries antibiotic-resistance genes. This structure is called | Plasmid | Ribosome | |
| Which statement is true? | Some bacteria produce toxins while many do not | All bacteria produce toxins | |
| A bacterium attaches to a host cell and causes the cell membrane to wrap around it bringing the bacterium into the cell. This process is called | Endocytosis | Exocytosis | |
| A gram-negative bacterium commonly carried in the respiratory tract enters the bloodstream and crosses the blood-brain barrier causing meningitis. Which organism is most likely responsible? | Neisseria meningitidis | Clostridium tetani | |
| Which statement correctly compares the functions of fimbriae and a sex pilus? | Fimbriae help bacteria attach to host cells while sex pili transfer DNA during conjugation | Fimbriae transfer plasmids between bacteria while sex pili help bacteria attach to host tissues | |
| Which statement about endotoxin is true? | Most gram-negative bacteria possess endotoxin because Lipid A is part of their outer membrane | Endotoxin is a protein secreted by bacteria | |
| Which bacterial structure is most directly responsible for endotoxin activity? | Lipid A | Fimbria | |
| The toxic effects of Lipid A occur primarily because Lipid A | Lipid A activates macrophages which release TNF | TNF lowers blood pressure; Lipid A triggers TNF release | |
| Which statement correctly distinguishes antibodies from white blood cells? | Antibodies are proteins produced by B cells, whereas white blood cells are immune cells | Antibodies are a type of leukocyte | |
| A patient develops a bacterial skin infection. Histamine is released at the site of infection, causing increased capillary permeability. Why is this response beneficial to the complement system? | It allows complement proteins to leave the bloodstream and enter the infected tissue | It allows bacteria to enter the bloodstream more easily | |
| A health department tracks a disease that appears only occasionally and unpredictably in a community. Some months there are no cases, while other months there may be one or two isolated cases. This pattern is best described as | Sporadic disease | Latent infection | |
| Which disease is spread primarily through respiratory droplets? | Diphtheria | Malaria | |
| A patient with severe gram-negative bacteremia becomes hypotensive shortly after initiation of antibiotic therapy. The most likely explanation is | Rapid bacterial death released endotoxin stimulating TNF production | The antibiotic directly caused vasodilation | |
| Which microscope part controls the amount of light passing through the specimen? | Iris diaphragm | Condenser | |
| Which microscope component is responsible for concentrating and focusing light onto the specimen? | Condenser | Iris diaphragm | |
| On a standard compound light microscope which color band indicates 40x high-power objective lens? | Blue | White | |
| On a standard compound light microscope which color band indicates 4x scanning objective lens? | Red | Yellow | |
| On a standard compound light microscope which color band indicates 10x low-power objective lens? | Yellow | White | |
| On a standard compound light microscope which color band indicates 100x oil immersion objective lens? | White | Blue | |
| A microscope has excellent resolving power. What does this mean? | It can distinguish two closely spaced objects as separate | It makes objects appear larger | |
| Why should you never lower the body tube while looking through the ocular lens? | The objective lens may strike and damage the slide | It decreases magnification | |
| Which action is appropriate when using the 100× oil immersion objective? | Use fine adjustment only | Rotate the 40× lens through the oil to compare images | |
| A microbiology student wants to determine whether a bacterial species exhibits true motility rather than movement caused by water currents or Brownian motion. Which preparation should be used? | Hanging drop | Wet mount | |
| A student wants a rapid examination of live protozoa from pond water. The primary goal is simply to observe living organisms and their general characteristics. Which technique is most appropriate? | Wet mount | Hanging drop | |
| A microbiologist wants to determine whether a bacterial species destroys red blood cells. Which medium should be used? | Blood agar | Mannitol salt agar | |
| A microbiologist wants to isolate gram-negative bacteria from a mixed specimen and determine whether the bacteria ferment lactose. Which medium should be used? | MacConkey agar | Mannitol salt agar | |
| A microbiologist suspects a wound infection is caused by a species of Staphylococcus and wants to determine whether the organism ferments mannitol. Which medium should be used? | Mannitol salt agar | MacConkey agar | |
| A microbiologist determines that an unknown bacterium ferments lactose. Which of the following conclusions is most accurate? | The bacterium can metabolize lactose to produce energy | The bacterium is anaerobic | |
| A microbiology student observes bacterial colonies with a distinctive red pigment growing on an agar plate. Which organism is most likely present? | Serratia marcescens | Staphylococcus aureus |
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