Micro quizzes (for exam 2)

Microorganisms play an important role in each of the following processes except a. Air pollution | b. Causing infection | c. Decomposing organic material | d. Food production

Air pollution

Which of the following best describes bacterial endospores? a. Structures used for motility | b. Capsules that prevent phagocytosis | c. Active, dividing cells | d. Specialized, resting cells highly resistant to damage

Specialized, resting cells highly resistant to damage

All pathogens known to infect humans have been identified. a. True | b. False

False

All six major categories of microbes are using ___ as their genetic material.

Nucleic acids

Which of the following is not equal to 1 mm? a. 100 μm | b. 0.001 m | c. 1,000,000 nm | d. 0.1 cm

100 μm

A prokaryotic cell may possess all of the following except a. A cell membrane | b. Flagella | c. A nucleus | d. Ribosomes

A nucleus

The bacterial shape of the cells in the scanning electron micrograph shown in Figure 1.1 would best be described as a. Ovoid | b. Coccus | c. Spiral | d. Bacillus

Bacillus

Which statement is incorrect about prokaryotic cells? a. Their DNA is not enclosed within a membrane | b. They reproduce by binary fission | c. They lack membrane-enclosed organelles | d. They lack a plasma membrane

They lack a plasma membrane

All cells possess a cell wall. a. True | b. False

False

Microbes that naturally and mutualistically live in the human body and provide protection and production of essential vitamins and other compounds are called the ___. a. Microbiota (or normal microbiota) | b. Pathogenic microorganisms | c. Virulent microorganisms | d. Transient microbiota

The microbiota (or normal microbiota)

What happens to an enzyme during competitive inhibition? a. It binds to a cofactor | b. An inhibitor binds the active site | c. It is permanently destroyed | d. An inhibitor binds a separate allosteric site

An inhibitor binds the active site

___ allows a cell to transport substances from a lower to a higher concentration area. a. Simple diffusion | b. Facilitated diffusion | c. Active transport | d. Extracellular enzymes

Active transport

The difference between simple diffusion and facilitated diffusion is that facilitated diffusion ___. a. Moves materials from higher to lower concentration | b. Moves materials from lower to higher concentration | c. Requires ATP | d. Requires transporter proteins

Requires transporter proteins

You have isolated a motile gram-positive cell with no visible nucleus. You can safely assume that the cell ___. a. Has 2 flagella | b. Has a mitochondrion | c. Has a cell wall | d. Lives in an extreme environment

Has a cell wall

Anabolic reactions are characterized by a. Releasing energy | b. Breaking down large molecules | c. Using energy to build larger molecules | d. Oxidizing glucose to CO₂

Using energy to build larger molecules

An enzyme that includes its apoenzyme and cofactor is called a ___. a. Catalyst | b. Zymogen | c. Holoenzyme | d. Substrate

Holoenzyme

In this figure, which diagram of a cell wall is a gram-negative cell wall? a. A | b. B | c. Both A and B | d. Neither A nor B

B

Endospores are a reproductive structure. a. True | b. False

False

What happens during oxidation in a redox reaction? a. Gain of electrons | b. Loss of electrons | c. Gain of protons | d. Gain of energy

Loss of electrons

The major function of enzymes is to increase the activation energy requirements of a chemical reaction. a. True | b. False

False

Fermentation differs from aerobic respiration because a. It does not require oxygen | b. It uses the ETC | c. It generates more ATP | d. It produces glucose

It does not require oxygen

What are the products of glycolysis? a. CO₂, H₂O, and ATP | b. 2 pyruvate, ATP, NADH | c. Acetyl-CoA, CO₂ | d. Glucose and oxygen

2 pyruvate, ATP, NADH

Where does glycolysis occur in prokaryotic and eukaryotic cells? a. Both in cytoplasm | b. Both in mitochondrial matrix | c. Cytoplasm in prokaryotes and mitochondrial matrix in eukaryotes | d. Cytoplasm in prokaryotes and mitochondrial inner membrane in eukaryotes

Both in cytoplasm

What is the role of Acetyl-CoA in cellular respiration? a. Inhibits enzyme activity | b. Fermentation byproduct | c. Enters the Krebs cycle | d. Final electron acceptor

Enters the Krebs cycle

Which organism is not correctly matched to its energy source? a. Photoheterotroph — light | b. Photoautotroph — CO₂ | c. Chemoautotroph — NH₃ | d. Chemoheterotroph — glucose

Photoautotroph — CO₂

What type of reaction is shown in this figure? a. Decarboxylation | b. Transamination | c. Dehydrogenation | d. Oxidation

Transamination

Which compound is not produced during the Krebs cycle? a. FADH₂ | b. NADH | c. ATP | d. NADPH

NADPH

ATP molecules are created from catabolic pathways and consumed in anabolic pathways in living cells. a. True | b. False

True

Both cellular respiration and photosynthesis require an electron transport chain to finalize ATP production. a. True | b. False

True

Salts and sugars preserve foods by creating a ___. a. Depletion of nutrients | b. Hypotonic environment | c. Lower pH | d. Hypertonic environment

Hypertonic environment

Why must most milk sold in the U.S. be refrigerated, while evaporated canned milk and shelf-stable milk do not need refrigeration until opened? a. U.S. milk contains more sugar | b. Evaporated and shelf-stable milk undergo sterilization, whereas regular milk is pasteurized at lower temperatures | c. European milk contains antimicrobial proteins | d. Cardboard packaging prevents contamination

Evaporated and shelf-stable milk undergo sterilization, whereas regular milk is only pasteurized at lower temperatures, requiring refrigeration

Most bacteria grow best at pH ___. a. 3 | b. 5 | c. 7 | d. 9

7

Which is the best definition of generation time? a. Length of lag phase | b. Length of time needed for a cell to divide | c. Minimum rate of doubling | d. Duration of log phase

The length of time needed for a cell to divide

Which pair of microbe classification terms and optimal growth temperatures is mismatched? a. Psychrotroph — 20–30°C | b. Thermophile — 37°C | c. Hyperthermophile — greater than 80°C | d. Psychrophile — 15°C

Thermophile — growth at 37°C

During which growth phase are gram-positive bacteria most susceptible to penicillin? a. Lag | b. Log | c. Death | d. Equally susceptible during all phases

Log phase

Patients with indwelling catheters are susceptible to infections because a. Injected solutions are contaminated | b. Their immune systems are weakened | c. Infections are transmitted from other people | d. Biofilms develop on catheters

Biofilms develop on catheters

Application of heat to living cells can result in all except a. Damage to nucleic acids | b. Alteration of membrane permeability | c. Denaturation of enzymes | d. Decreased thermal death time

Decreased thermal death time

An isolated colony on a streak plate contains millions of identical cells that arose from one initial cell. a. True | b. False

True

Moist heat destroys microorganisms by denaturing protein. a. True | b. False

True

In a bacterial growth curve, which phase shows the number of cells dying equals the number dividing? a. A | b. B | c. C | d. D

C (stationary phase)

Which Gram-stain error/outcome pairing is correct? a. Alcohol omitted Gram-positive purple, Gram-negative pink | b. Safranin omitted

Which method is best to sterilize heat-labile solutions? a. Dry heat | b. Autoclave | c. Membrane filtration | d. Freezing

Membrane filtration

Bacterial cell-wall chemical composition is responsible for bacterial shape and differences in Gram-stain reaction. a. True | b. False

True

Enzymes are a. Biological catalysts | b. Used up in reactions | c. Always carbohydrates | d. Inhibited by coenzymes

Biological catalysts

Which control methods correctly match the situations? 1. Sterilize reusable surgical forceps; 2. Reduce microbes in fruit juice while preserving flavor; 3. Remove bacteria from heat-sensitive antibiotic solution; 4. Clean a lab bench after a culture spill.

a. 1–Autoclaving; 2–Pasteurization; 3–Filtration; 4–Disinfection | b. 1–Autoclaving; 2–Refrigeration; 3–Boiling; 4–Antisepsis |

c. 1–Pasteurization; 2–Autoclaving; 3–Boiling; 4–Sanitization |

d. 1–Pasteurization; 2–Freezing; 3–Filtration; 4–Sterilization

1–Autoclaving; 2–Pasteurization; 3–Filtration; 4–Disinfection

Which feature contributes to the greater barrier function of Gram-negative bacteria against some antibiotics and disinfectants? a. Thick capsule | b. Outer membrane | c. Teichoic acid | d. Thick peptidoglycan

Outer membrane

According to the operon model, for synthesis of an inducible gene to occur, the a. End-product must not be in excess | b. Substrate must bind to enzyme | c. Substrate must bind to protein repressor | d. Repressor must bind to operator

Substrate must bind to the protein repressor

Two bacterial genes differ in DNA sequence but make proteins with identical amino acid sequences. What is the most likely explanation? a. Mutations are corrected after translation | b. Mutations do not affect protein sequence due to degeneracy of the genetic code | c. Mutations are repaired at mRNA level | d. DNA mutations are not reflected in proteins

Mutations lie at locations where they do not affect protein sequence due to degeneracy of the genetic code

A gene is ___. a. Any random DNA segment | b. A three-nucleotide segment coding for an amino acid | c. A sequence of DNA nucleotides that codes for a functional product | d. The RNA product of transcription

A sequence of nucleotides in DNA that codes for a functional product

Gene transfer by conjugation differs from reproduction because ___. a. DNA replicates | b. DNA transfers vertically | c. DNA transfers horizontally to nearby cells | d. DNA is transcribed to RNA

Conjugation transfers DNA horizontally to nearby cells

All are true except a. DNA polymerase joins nucleotides 5′ to 3′ only | b. Leading strand is made continuously | c. Lagging strand starts with an RNA primer | d. DNA replication proceeds in only one direction around bacterial chromosome

DNA replication proceeds in only one direction around the bacterial chromosome

Transduction requires a(n) ___ to move DNA between bacterial cells. a. Bacteriophage | b. Naked DNA molecule | c. F plasmid | d. Transposase enzyme

Bacteriophage

Both base substitution and frameshift mutations can result in premature stop codons. a. True | b. False

True

Protein synthesis in eukaryotes and prokaryotes requires ___. a. Exons | b. Introns | c. Codons to determine polypeptide sequences | d. Methionine as the start amino acid

The use of codons to determine polypeptide sequences

Which pair is mismatched? a. DNA polymerase — DNA from DNA template | b. RNA polymerase — RNA from RNA template | c. DNA ligase — joins DNA segments | d. Transposase — cuts DNA backbone, leaving sticky ends

RNA polymerase — makes a molecule of RNA from an RNA template

Genetic changes in bacteria can be accomplished by mutation, conjugation, transduction, and transformation. a. Mutation only | b. Conjugation only | c. Transduction only | d. All of the answers are correct

All of the answers are correct

Which pair of microbes are both prokaryotic but differ in cell-wall composition and typical environment? a. Staphylococcus and Escherichia coli | b. Cyanobacteria and green algae | c. Halobacterium and Sulfolobus | d. Halobacterium and Staphylococcus

Halobacterium and Staphylococcus

Chloroplasts possess circular DNA and reproduce by binary fission. a. True | b. False

True

A genus can best be defined as a. A taxon composed of families | b. A taxon composed of one or more species below family | c. A taxon belonging to a species | d. A taxon composed of classes

A taxon composed of one or more species and a classification level lying below family

Which microbe is eukaryotic, non-motile, and uses an apical complex to invade host cells, causing malaria? a. Amoeba | b. Ciliate | c. Apicomplexan | d. Flagellate

Apicomplexan

The highest level in the current taxonomic hierarchy is Kingdom. a. True | b. False

False

Which microbe is most likely a member of Domain Archaea? a. Gram-positive cocci causing skin infections | b. Ciliate causing intestinal infections | c. Thrives in salty environments, lacks peptidoglycan, produces methane | d. Filaments with chitin cell walls

Thrives in salty environments, lacks peptidoglycan, produces methane

Which microbe is a photosynthetic prokaryote that performs oxygenic photosynthesis and may fix nitrogen? a. Green algae | b. Blue-green algae | c. Trichomonas vaginalis | d. Plasmodium falciparum

Blue-green algae (cyanobacteria)

Which best characterizes Domain Bacteria? a. Eukaryotic cells with organelles | b. Prokaryotes lacking peptidoglycan | c. Prokaryotes with peptidoglycan cell walls | d. Cells with a true nucleus

Prokaryotic cells with peptidoglycan in their cell walls

Why are viruses not classified in one of the three domains of life? a. Some incorporate genomes into host genomes | b. They direct host anabolic pathways | c. They are obligate parasites | d. They are not composed of cells

They are not composed of cells

Which correctly matches a microbe with its movement or invasion method? a. Trichomonas vaginalis — pseudopodia | b. Balantidium coli — cilia | c. Plasmodium falciparum — flagella | d. Amoeba — apical complex

Balantidium coli — uses cilia for movement

Which statement about viral spikes is false? a. They are carbohydrate-protein complexes | b. Used for attachment | c. Found only on nonenveloped viruses | d. Bind host-cell receptors

They are found only on nonenveloped viruses

Viruses are the only known infectious agents that are obligate intracellular parasites. a. True | b. False

False

Which statement about the eclipse period is true? a. Viruses are entering cells | b. Mature virions are released | c. Viral components are synthesized, but no complete virions are present | d. Viruses are inactivated by the immune system

Viral components are being synthesized, but no complete virions are present

Which is the first step in biosynthesis of a virus with a minus-strand RNA genome? a. DNA from RNA | b. Double-stranded RNA from an RNA template | c. Double-stranded RNA from DNA | d. DNA from DNA

Synthesis of double-stranded RNA from an RNA template (as given in the quiz)

Lysogeny is the process in which a. Phage DNA is incorporated into host DNA | b. Host cell lysis occurs | c. Virions are absent during replication | d. Burst time is unusually long

Phage DNA is incorporated into host cell DNA

Which best describes the latent period in a virus growth curve? a. Time viruses attach | b. Time from entry to first appearance of extracellular viruses | c. Time viruses bud | d. Time viruses are detectable in blood

Time from entry to first appearance of extracellular viruses

Bacteriophage replication differs from animal virus replication because only bacteriophage replication involves ___. a. Adsorption to receptors | b. Assembly of components | c. Replication of nucleic acid | d. Injection of naked nucleic acid into the host cell

Injection of naked nucleic acid into the host cell

Which best describes a symbiotic relationship? a. Both organisms must benefit | b. One always benefits and one is harmed | c. Two organisms live in close association and at least one may benefit | d. Organisms must depend on each other for survival

Two different organisms live in close association, and at least one may benefit

Which statement about viruses is incorrect? a. Contain DNA or RNA but never both | b. Contain a protein coat | c. Use host anabolic machinery | d. Use their own catabolic enzymes

Viruses use their own catabolic enzymes

Positive-sense RNA strands of viruses are treated like mRNA inside the host cell. a. True | b. False

True

Which statement about exotoxins is not often true? a. More potent than endotoxins | b. Resistant to heat | c. Have specific methods of action | d. Produced by gram-positive bacteria

They are resistant to heat

Which statement is true about a symbiotic relationship? a. Both members are harmed | b. Members cannot live without each other | c. Symbiosis always means both benefit | d. At least one member must benefit

At least one member must benefit

A healthcare-associated infection (traditionally known as nosocomial infection) is ___. a. Always present but inapparent at hospitalization | b. Acquired during hospitalization | c. Always caused by medical personnel | d. Always caused by pathogenic bacteria

Acquired during hospitalization

Which cytopathic effect is cytocidal? a. Inclusion bodies | b. Antigenic changes | c. Transformation | d. Release of enzymes from lysosomes

Release of enzymes from lysosomes

Symptoms differ from signs of disease in that symptoms ___. a. Are changes felt by the patient | b. Are changes observed by physician | c. Are specific for a disease | d. Always occur in a syndrome

Are changes felt by the patient

In which pattern of disease does the patient experience no signs or symptoms? a. Prodromal | b. Convalescence | c. Incubation | d. Both incubation and convalescence

Both incubation and convalescence

The rise in herd immunity in a population can result from ___. a. Increased antibiotic use | b. Improved handwashing | c. Vaccinations | d. None of the answers

Vaccinations

Which of the following is not a communicable disease? a. Malaria | b. AIDS | c. Tetanus | d. Typhoid fever

Tetanus

Which correctly describes four major virulence mechanisms of Salmonella? a. Adhesion, toxin production, resistance, spore formation | b. Adhesion, invasion, intracellular survival, inflammation/immune evasion | c. Biofilm, capsule, extracellular replication, toxin | d. Motility, resistance, spores, intracellular survival

Adhesion, invasion, intracellular survival, and inflammation/immune evasion

Emerging infectious diseases are the result of all the following except a. Antibiotic resistance | b. Climatic changes | c. Ease of travel | d. New strains of known agents | e. All answers are correct

All of the answers are correct

Compare prokaryotic and eukaryotic microbes, including DNA location/organization, membrane-bound organelles, shared/unique structures, size/complexity, and examples.

Prokaryotes

Describe the five oxygen-requirement categories and their growth patterns in a tube.

Obligate aerobe

Choose two microbial categories and explain two most effective and two least effective control methods for each, including germicidal, germistatic, or mechanical action.

Select methods appropriate to each organism and explain why. Avoid reusing a method across categories; distinguish killing, inhibiting growth, and mechanical removal.

Explain sterilization, disinfection, antisepsis, and sanitization. Define each, give an example, describe effectiveness, and identify appropriate use.

Sterilization destroys all microbial life including endospores; disinfection destroys many pathogens on inanimate objects; antisepsis reduces/inhibits microbes on living tissue; sanitization reduces microbial numbers to safe public-health levels.

Compare cellular respiration and fermentation of glucose, including steps, reactants/products, functions, locations, examples, and energy yield.

Respiration includes glycolysis, Krebs cycle, and ETC and yields much more ATP. Fermentation follows glycolysis, regenerates NAD+, does not require oxygen, and yields 2 ATP; examples include lactic-acid bacteria and yeast.

Compare Gram-positive and Gram-negative bacteria by Gram-stain response, cell-wall structure, similarities/differences, and penicillin susceptibility.

Gram-positive

Identify at least one way Gram-positive and Gram-negative bacteria differ in susceptibility to microbial control methods, excluding penicillin, and explain the structural or physiological reason.

Use a course microbial-control method and explain susceptibility in terms of cell-wall/outer-membrane structure. The pasted question did not include a model answer.