Q&A Hero

Q: ________ are toxic proteins released from the pathogen as it grows. A) Endotoxins B) Exotoxins C) Macrotoxins D) Microtoxins

Q: The condition that results when some organisms are shed in the bloodstream and distributed to distant parts of the body during bacterial growth in tissues is called A) septicemia. B) bacteremia. C) uremia. D) erythemia.

Q: The process by which white blood cells ingest and kill bacteria is called A) exocytosis. B) transcription. C) phagocytosis. D) translation.

Q: A loose network of polymers extending outward from a cell is called a(n) A) slime layer. B) lipid A. C) capsule. D) adhesion.

Q: The macromolecules responsible for bacterial adherence that are NOT covalently attached to bacteria are collectively called A) lipid A. B) biofilms. C) capsules. D) glycocalyx.

Q: The process by which microorganisms cause diseases is known as A) pathogenesis. B) virulence. C) LD50 (lethal dose50). D) infection.

Q: The dose of an antigen that kills 50% of animals in a test group and is used to estimate the virulence of a pathogen is known as A) Antigen dose50. B) Virulence-50. C) LD50 (lethal dose50). D) Death rate-50.

Q: Which of the following is a major growth-limiting micronutrient that influences microbial growth? A) iron B) transferrin C) lactoferrin D) sugar

Q: Which of the following pathogens does NOT require capsules or a slime layer for attachment? A) Vibrio cholera B) Streptococcus pneumonia C) Bacillus anthracis D) All of these pathogens require capsules or slime layers for attachment.

Q: Extensive growth of the streptococci in a thick bacterial layer on acidic glycoproteins on the teeth is called A) dental plaque. B) dental caries. C) dental biofilm. D) periodontitis.

Q: Which of the following environmental and host factors influence the composition of resident microflora on the skin? A) age B) personal hygiene C) weather D) age, personal hygiene, and weather

Q: Which of the following is the dominate genera of skin microflora? A) Bacteriodes B) Firmicutes C) Actinobacteria D) Proteobacteria

Q: Virulence is the relative ability of a ________ to cause disease. A) pathogen B) commensal C) virus D) bacterium

Q: A(n) ________ is a damage or injury to a host organism that impairs its function. A) trauma B) infection C) disease D) transmission

Q: The human gastrointestinal tract includes all of the following EXCEPT the A) small intestine. B) stomach. C) large intestine. D) epiglottis.

Q: Which of the following is a way to prevent attenuation and maintain virulence in a bacterium? A) laboratory subculture B) animal passage C) polymerase chain reaction (PCR) D) antibiotic therapy

Q: ________ in saliva cleaves glycosidic linkages in peptidoglycan present in bacterial cell walls, weakening the wall and causing cell lysis. A) Mucus B) Lysozyme C) Fibrin D) Lipid A

Q: The collective term for the organisms living on or in the human body is A) normal microbial flora. B) fomite flora. C) transient microbial flora. D) pathogenic flora.

Q: Normal flora ________ colonization of pathogenic organisms. A) promote B) prevent C) maintain D) accelerate

Q: Cytolytic toxins A) are extracellular proteins. B) cause cell lysis and death. C) damage host cytoplasmic membrane. D) are extracellular proteins that cause cell lysis and death by damaging the host cytoplasmic membrane.

Q: Siderophores from some pathogens remove iron from the host protein(s) A) lactoferrin. B) transferrin. C) both lactoferrin and transferrin. D) cytochromes.

Q: Which of the following does NOT affect pathogen growth? A) availability of microbial nutrients B) pH C) temperature D) doubling time

Q: Pathogenic strains of Escherichia coli usually express A) capsules. B) colonization factor antigens (CFA). C) plaques. D) slime layers.

Q: Which of the following is more likely to cause urinary tract infections? A) fimbriated strains of Escherichia coli B) non-fimbriated strains of Escherichia coli C) both fimbriated and non-fimbriated strains of Escherichia coli D) None of the answers are correct.

Q: Which genus produces hyaluronidase? A) Mycobacteria B) Streptococcus C) Shigella D) Procholorococcus

Q: The spread of pathogens through the blood and lymph systems that results in a bloodborne systemic infection is called A) bacteremia. B) cancer. C) pathogenesis. D) septicemia.

Q: Which of the following is an important factor in the development of dental caries? A) high salt diet B) high sugar diet C) high acid diet D) low salt diet

Q: Which of the following is NOT important for the adherence of bacteria to other bacteria as well as to host tissue? A) adherence polymers B) capsule C) glycocalyx D) slime layer

Q: Which disease CANNOT be prevented via the use of a vaccine generated from an attenuated pathogen? A) malaria B) measles C) mumps D) rubella

Q: Attenuation occurs in a laboratory, because A) nonvirulent or weakly virulent mutants grow faster in vitro in laboratory media. B) pathogens lose virulence with age. C) patients are generally treated with drugs that induce attenuation. D) None of the answers are correct.

Q: The decrease or loss of virulence of a pathogen is referred to as A) aging. B) attenuation. C) disinfectivity. D) lethal dose.

Q: Capsules are particularly important for A) making bacteria more vulnerable to host defense mechanisms. B) making bacteria less pathogenic. C) protecting bacteria from host defense mechanisms. D) allowing bacteria to become more phagocytic.

Q: A polymer coat consisting of a dense, well-defined polymer layer surrounding a cell is called a A) capsule. B) glycocalyx. C) lipopolysaccharide. D) slime mold.

Q: Influenza virus targets A) respiratory epithelium. B) gastrointestinal cells. C) oral cavity cells. D) throat epithelium.

Q: Streptocoocus pyogens utilizes M protein and ________ to form microfibrils that facilitate attachment to host cells. A) lipoteichoic acid B) mucus C) plaque D) None of the answers are correct.

Q: Which of the following hemolysins is a phospholipase? A) lecithinase B) Streptolysin-O C) Staphylococcal -toxin D) leukocidin

Q: The vagina of adult female is A) highly acidic. B) highly alkaline. C) weakly acidic. D) weakly alkaline.

Q: Only particles smaller than ________ m in diameter reach the lungs. A) 10 B) 20 C) 30 D) 40

Q: Staphylococcus aureus produces ________, leading to fibrin clots that protect them from attack by host cells. A) collagenase B) coagulase C) lipase D) amylase

Q: The following compounds are all produced by intestinal microflora EXCEPT A) flatus. B) vitamin C. C) vitamin B12. D) vitamin K.

Q: Which of the following are NOT found in the gastrointestinal tract of healthy humans? A) Bacteroides B) Clostridium C) Escherichia coli D) protists

Q: Normal flora in the duodenum are A) similar to the microflora in the stomach. B) dominated by aerobic organisms. C) tolerant to alkaline environments. D) tolerant to high salinity.

Q: Which of these microorganisms is MOST likely to be found in the human gut? A) Helicobacter pylori B) Streptococcus sobrinus C) Streptococcus mutans D) Roseobacter denitrificans

Q: The following bacterial species are all implicated in dental caries EXCEPT A) Fusobacterium. B) Borrelia. C) Streptococcus. D) Lactobacillus.

Q: Decalcification of the tooth enamel due to the production of high concentrations of organic acids in the mouth is known as A) degenerative plaque. B) dental caries. C) dental plaque. D) microbial enamel decalcification.

Q: Following antibiotic therapy, patients are often administered ________ to facilitate recolonizaton of normal flora. A) fluoride B) iron C) probiotics D) antivirals

Q: One microenvironment of the skin is an area where glands produce an oily substance called A) mucus. B) sebum. C) fimbrae. D) lipid A.

Q: Which of the following is NOT a subunit of lipopolysaccharide (LPS)? A) O-specific polysaccharide B) lipid A C) core polysaccharide D) M protein

Q: Pathogenicity is the ability A) of the host to inflict damage on the pathogen. B) of the host to resist damage by the pathogen. C) of the pathogen to inflict damage on the host. D) None of these are correct.

Q: Archaea are commonly present in rumens.

Q: Bacterial cells themselves serve as major sources of protein and vitamins in hindgut fermenting animals such as rabbits and horses.

Q: Plant diversity is generally lower in environments where mycorrhizae are associated with plants due to strong coevolution, which leads to competitive exclusion.

Q: The mycelia of mycorrhizae can form underground nutrient networks where several trees are connected.

Q: An individual tree can maintain a symbiotic relationship with many different species of mycorrhizae simultaneously.

Q: While rhizobia usually associate with plant roots, nodules can also be formed along the stems of leguminous plants.

Q: Bacteroids are rarely found within plant cells.

Q: Several rhizobial species within a cross-inoculation group should be able to grow with particular legume species such as alfalfa. However, the same cross-inoculation group would be unable to associate with another legume species such as peas.

Q: Bacteria associated with plants fix very small amounts of nitrogen, therefore they do NOT contribute significantly to the global N cycle.

Q: Leguminous plants such as alfalfa, beans, clover, peas, and soybeans all benefit from symbiotic bacteria that leach vitamins into the plant roots.

Q: Consortia of a phototrophic green sulfur bacteria and motile heterotrophs are found worldwide in freshwater stratified sulfidic lakes.

Q: Which of the following is NOT a function of the human gut microbiome? A) production of essential amino acids and vitamins B) production of volatile fatty acids from polysaccharides C) iron and trace metal absorption D) maturation of the gastrointestinal tract

Q: Riftia tube worms contain unusual hemoglobins that bind(s) A) H2S and O2 in order to transport these chemicals to their bacterial symbionts. B) high concentrations of O2 produced by their photosynthetic symbionts. C) sulfate to transport this ion away from their bacterial symbionts. D) ammonia that their bacterial symbionts produce.

Q: Bacterial symbionts most often provide marine invertebrates with A) fixed nitrogen in the form of ammonia. B) essential amino acids missing from the animal's diet. C) cellulolytic enzymes to help digest plant material. D) fixed carbon dioxide in the form of organic compounds.

Q: The structural and trophic foundation of coral reefs is a mutualistic relationship between A) cyanobacteria and sponges (Porifera). B) chemolithotrophic bacteria and stony corals (Cnidaria). C) dinoflagellates and stony corals (Cnidaria). D) cyanobacteria and stony corals (Cnidaria).

Q: Allivibrio fischeri symbionts benefit the Hawaiian bobtail squid by A) mimicking the light of the moon, which helps the squid avoid nocturnal predators. B) providing essential amino acids missing from the squid's diet. C) degrading the cellulosic cell walls of the phytoplankton the squid eats. D) providing essential amino acids missing from the squid's diet and degrading the cellulosic cell walls of the phytoplankton the squid eats.

Q: Aphids that feed on carbohydrate-rich but nutrient-poor foods obtain________ from their endosymbiotic bacterial partners. A) ATP B) amino acids C) ammonium D) volatile fatty acids

Q: Lichens are a mutualistic association of a fungus and either an alga or a cyanobacterium in which A) the fungus protects the photosynthetic partner from erosion. B) the fungus slowly engulfs the photosynthetic partner. C) the fungus helps collect sunlight for the photosynthetic partner. D) the phototroph provides phosphorus to the fungus.

Q: ________ are intracellular bacteria that are usually localized to specialized organs within their host. A) Symbiodinium B) Arbuscules C) Epibionts D) Endosymbionts

Q: The human oral flora consists of A) a small group of phylogenetically related aerobic microorganisms. B) diverse aerobic and anaerobic microorganisms. C) monoculture biofilms on tooth surfaces. D) the same phyla that are found in the human gut.

Q: The most heavily colonized human organ by bacteria is the ________, containing 1011-1012 bacterial cells per g. A) mouth B) small intestine C) large intestine D) skin

Q: In mycorrhizal mutualisms between plants roots and fungi, A) the plant supplies carbohydrates to the fungus and the fungus supplies phosphorus and nitrogen to the plant. B) the plant supplies water to the fungus and the fungus supplies essential amino acids to the plant. C) the plant protects the fungus from predation and the fungus supplies carbohydrates to the plant. D) the fungus infects the plant roots, stimulating plant growth through myc factors that act as growth hormones in the plant.

Q: During the Jurassic Period, several different mammalian lineages independently evolved an herbivorous lifestyle for obtaining energy. This has resulted in A) different digestive patterns in herbivorous animals, some that depend on gut microbiota to digest plant material and some that do not. B) different digestive patterns in herbivorous animals that all depend on gut microbiota to digest plant material. C) the evolution of foregut fermentation, as seen in ruminants, as the only digestive pattern that depends on fermentative gut microbiota. D) horizontal gene transfer of genes for glycoside hydrolases and polysaccharide lyases from bacteria to mammals.

Q: The signaling factors of arbuscular mycorrhizae most likely gave rise to the signaling factors used in rhizobial nodule formation, yet less is known about arbuscular mycorrhizae because A) they cannot be maintained in pure culture. B) they are not as important for plant health. C) no genetic systems have been developed for fungi. D) they are not as important for plant health and no genetic systems have been developed for fungi.

Q: A mutant of Rhizobium leguminosarum is able to survive and reproduce in the laboratory outside of plant roots, but can no longer initiate root nodule formation. What type of genes are most likely mutated in this mutant? A) rhz genes B) myc genes C) nif genes D) nod genes

Q: How are root nodule and arbuscular mycorrhizal symbioses similar? A) They both use lipochitin oligosaccharide signaling factors to initiate root colonization. B) They both supply nitrogen to the host plant through nitrogen fixation. C) They both increase absorption of nutrients from soil. D) They are both required for the growth and reproduction of their host plants.

Q: Which of the following is a common benefit of a microbe-plant symbiosis? A) increased nutrient availability B) decreased pathogen colonization C) increased affinity for carbon dioxide D) increased nutrient availability and decreased pathogen colonization

Q: When the squid that contain luminescent bacterial symbionts hatch, they do NOT contain a bacterial symbiont. Symbiont transmission in this symbiosis is A) vertical from parent to offspring. B) horizontal and involves specific selection of the symbiont from the environment. C) random and results in various different species being selected as the symbiont. D) mixed and results in multiple symbiont species colonizing the squid at once.

Q: A species of insect that lives solely on pine sap was found to contain a bacterial symbiont. Genome sequencing of both the host and the symbiont revealed that the symbiont lacked many genes required for energy production, and the host lacked genes for biosynthesis of several essential amino acids. What is/are the most likely mechanism(s) that caused the loss of these genes? A) coevolution B) horizontal gene transfer C) increased mutation rate D) horizontal gene transfer and increased mutation rate

Q: Why do obligate symbionts often contain lower G+C content when compared to free-living organisms? A) Ancestral symbionts had low GC content genomes by chance, and these low GC content genomes are passed onto their progeny. B) Free-living organisms must have a more stable genome to survive; low G+C content organisms are often selected against in nature. C) Replicating high G+C content genomes requires several additional enzymes, to break apart the strong triple bonds formed from GC pairs, which are rarely found in symbionts with relatively small genome sizes. D) Symbionts usually do not have as many DNA repair mechanisms as free-living organisms, and two common spontaneous mutations change GC pairs into AT pairs.

Q: Which of the following is NOT true of human gut microbes? A) The population size is low, but diversity is high. B) They produce and excrete amino acids. C) They help catabolize polysaccharides. D) They are involved in the "maturing" of the gastrointestinal tract.