Chapter 34: The Microbe-Human Ecosystem

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Although the human microbiome is dominated by five major phyla, at the species level, the average adult gut hosts _____ different microbial species. millions of 500-1,000 tens of thousands of a few dozen

500-1,000

Which of the following statements regarding the core microbiome is false? The core microbiome is usually described at the level of genus. The core microbiome collectively accomplishes specific metabolic functions. A core microbiome is found in an individual throughout his/her life, regardless of environmental conditions. A core microbiome describes a group of taxa consistent among a population with a common feature.

A core microbiome is found in an individual throughout his/her life, regardless of environmental conditions.

Which of the following statements regarding the functional core microbiome is false? A functional core microbiome has been identified for the human gut, and is a list of common genera. A functional core microbiome includes those microbes that contribute to the development of the immune system. The synthesis of vitamin K by Escherichia coli is one part of the functional core microbiome. The community metabolism in the microbiome is a more important measure than the individuals responsible for that metabolism.

A functional core microbiome has been identified for the human gut, and is a list of common genera.

Body odor is largely due to which one of these? Bacterial degradation of lipids Dead and dying bacteria on the skin Bacterial fermentation of sugars Accumulation of sweat

Bacterial degradation of lipids

Which of these results in increased numbers of beneficial bifidobacteria in a child's intestinal tract? Bottle feeding instead of breast feeding Adding solid food to the diet Switching from breast milk to cow's milk Breast feeding

Breast feeding

Identify the false statement regarding the development of a stable microbiome. An adolescent has a different community of microbes than her grandmother, despite sharing a home. Early childhood is a critical time for establishing a healthy microbiome to help the immune system mature. The normal community of human-associated microbes begins at the moment of birth. By the end of its first year, a child has developed an adult-like community of human-associated microbes.

By the end of its first year, a child has developed an adult-like community of human-associated microbes. (not until the third year)

Which of the following statements regarding the use of probiotics on livestock is false? Beef cattle show reduced carriage of E. coli O157:H7 when treated with Lactobacillus acidophilus. Chickens show reduced carriage of Helicobacter by treatment with a probiotic strain of Bacillus subtiis. Use of probiotics may decrease antibiotic use in large scale livestock processing.

Chickens show reduced carriage of Helicobacter by treatment with a probiotic strain of Bacillus subtiis.

Which bacterial species is most closely associated with the development of the skin condition called acne vulgaris? Staphylococcus epidermidis Staphylococcus aureus Cutibacterium acnes Corynebacterium acnes

Cutibacterium acnes

Identify the false statement regarding the use of probiotics on livestock. Use of probiotics may decrease antibiotic use in large scale livestock processing. Chickens show reduced carriage of Campylobacter by treatment with a probiotic strain of Bacillus subtilis. Beef cattle show reduced carriage of E. coli O157:H7 when treated with Lactobacillus acidophilus. Day-old lambs are treated with a blend of 29 bacteria to help establish a health microbiome.

Day-old lambs are treated with a blend of 29 bacteria to help establish a health microbiome.

The early colonization of the infant intestinal tract by _____ and _____ appears to establish a reducing environment for the growth of anaerobes such as bifidobacteria and bacteroidetes. Lactobacillus staphylococci E. coli Clostridium streptococci

E. coli streptococci

True or false: The anatomy and physiology of human skin do not vary, therefore the normal microbiota of the skin is consistent throughout the body. True False

False

In the duodenum, the low number of bacteria present are mostly _____. Gram-positive Gram-negative

Gram-positive

To reduce the production of volatile unsaturated fatty acids, many deodorants contain antimicrobial substances that selectively inhibit which of these? Gram-negative bacteria Gram-positive bacteria Fungi Protists

Gram-positive bacteria

Identify the false statement regarding the human microbiome. There is no single healthy microbiome, but many possible healthy microbiomes. Identical twins must have identical microbiomes. Both breast-fed and bottle-fed infants will develop healthy microbiomes. A history of taking prescription drugs may alter a person's microbiome.

Identical twins must have identical microbiomes.

In which body region do bacteria contribute to these conditions: caries, gingivitis, and periodontitis? Multiple choice question. Respiratory tract Skin Urogenital tract Mouth

Mouth

In addition to Actinobacteria and Fusobacteria, which three of the following are major phyla found on human skin, in the intestinal tract, and other mucosal surface? Proteobacteria Firmicutes Spirochaetes Crenarchaeota Bacteroidetes Cyanobacteria

Proteobacteria Firmicutes Bacteroidetes

Which of the following statements regarding experiments with germ-free (GF) mice and serotonin is false? Gut bacteria that produce butyrate induce host cells to produce serotonin. Serotonin is primarily produced in the brain, but also acts in the GI tract. GF mice have much lower blood levels of serotonin compared to conventional mice. Serotonin is involved in mood, appetite, sleep, learning, and memory.

Serotonin is primarily produced in the brain, but also acts in the GI tract.

Which of the following statements regarding the human microbiome is false? Babies born by Caesarean section will develop a healthy microbiome. Each individual's microbiome assembles over time and reflects their experiences. Exposure to medications affects the development of the microbiome. The healthiest human microbiome is found among vegetarians who don't use tobacco.

The healthiest human microbiome is found among vegetarians who don't use tobacco.

Which of the following statements concerning the microbiota of the respiratory tract is false? Multiple choice question. The lower respiratory tract has primarily transient microbes. The upper respiratory tract is colonized by a diverse group of microbes. The lower respiratory tract is sterile.

The lower respiratory tract is sterile.

Which of the following statements regarding the development of a stable microbiome is false? The normal community of human-associated microbes changes throughout an individual's lifetime. By age three years, a child has developed an adult-like community of human-associated microbes. The development of the immune system depends on the community of human-associated microbes. The normal community of human-associated microbes begins developing before a child is born.

The normal community of human-associated microbes begins developing before a child is born.

The human microbiome is best described as _____. all the microbes that reside in the human digestive tract microbes that actively metabolize in and on the human body microbes that are essential to human viability all the microbes that reside in and on a human body

all the microbes that reside in and on a human body

Bacteriocins kill target bacteria by forming pores and depolarizing membranes. Chemically, bacteriocins are _____. phospholipids acidic proteoglycans secondary bile acids amphipathic peptides

amphipathic peptides

Which of the following pairs of sites on the body can be expected to have highly similar microbiomes? an individual's left forearm, and his long-term partner's left forearm an individual's left forearm, sampled twice, a week apart an individual's left and right forearms an individual's left forearm and her scalp

an individual's left forearm, sampled twice, a week apart

Which of the following pairs of sites on the body can be expected to have highly similar microbiomes? an individual's left forearm, sampled twice, a week apart an individual's left forearm, and his long-term partner's left forearm an individual's left forearm and her scalp an individual's left and right forearms

an individual's left forearm, sampled twice, a week apart

In humans, the acquisition of a normal microbiota normally begins _____. during fetal development at about two months of age at birth

at birth

Animals that eat a meat-intensive diet introduce L-carnitine and phosphatidylcholine to their GI tract, where microbial metabolism converts them to trimethylamine. This compound is later oxidized in the liver to trimethylamine N-oxide, which is associated with the development of ______. diabetes mellitus atherosclerosis double-stranded DNA breaks inflammatory bowel disease

atherosclerosis

Toxic peptides produced by Gram-positive bacteria that target closely related strains or species are termed _____. microcins colicins lectins bacteriocins

bacteriocins

The early colonization of the infant intestinal tract by E. coli and streptococci appears to establish a reducing environment for the growth of which anaerobes? Clostridium bacteroidetes Lactobacillus bifidobacteria staphylococci

bacteroidetes bifidobacteria

The early colonization of the infant intestinal tract by E. coli and streptococci appears to establish a reducing environment for the growth of which anaerobes? bacteroidetes Lactobacillus staphylococci bifidobacteria Clostridium

bacteroidetes bifidobacteria

Viruses that alter their host cell cycle to promote proliferation and that prevent host cells from repairing DNA damage are responsible for the host cell _____. becoming cancerous cytokine production lysis and death protection from superinfection

becoming cancerous

Secretory IgA (SIgA) molecules coat mucosal surfaces where they _____. bind their microbial targets to promote clearance of foreign antigens convert carbohydrates in the diet to short chain fatty acids await stimulation by an antigen compatible with their receptors prevent passage of pathogen cells across the mucosal surface

bind their microbial targets to promote clearance of foreign antigens

Germ-free mice have limited development of the white blood cells of the innate immune system, all cells that mature in the _____. thyroid gut thymus bone marrow

bone marrow

Host intestinal cells are induced to produce serotonin in response to gut bacteria that produce _____. cytokines butyrate microcins polysaccharide A

butyrate

The skin bacterium Propionibacterium acnes breaks down lipid secretions to unsaturated fatty acids, some of which have strong antimicrobial activity against which two types of microbes? protists certain fungi Gram-positive bacteria Gram-negative bacteria viruses

certain fungi Gram-negative bacteria

Bacteriocins are toxic peptides produced by Gram-positive bacteria that target _____. endospores Gram-negative bacteria most Gram-positive bacteria closely related strains or species

closely related strains or species

The idea that a healthy gut microbiome is protective against the establishment of pathogens in the gut is termed _____. mucosal tolerance probiotic tolerance colonization resistance immune surveillance

colonization resistance

The core microbiome is a group of microorganisms that is _____. found in the large intestine of most individuals variable among individuals over time consistent among people who share a common feature found throughout most individuals

consistent among people who share a common feature

In addition to short chain fatty acids produced by the gut microbiota, immune cell maturation also requires _____ released by intestinal immune cells. toll-like receptors primary bile salts C-type lectins cytokines

cytokines

Which three of these are correct descriptions of human skin? dry in many areas some areas have sebum slightly alkaline high salt concentration warmest part of the body

dry in many areas some areas have sebum high salt concentration

The contribution of the microbiome to disease is called _____ dysbiosis commensalism parasitism inflammation

dysbiosis

The contribution of the microbiome to disease is called __________.

dysbiosis

The gut microbiota releases the fermentation product butyrate which helps to keep the oxygen tension low, thereby _____. inhibiting the growth of anaerobes lowering the toxicity of small peptides favoring the growth of anaerobes reducing the energy output

favoring the growth of anaerobes

Bacteriocins are amphipathic peptides that kill target bacteria by _____ and _____. [Choose two.] forming pores denaturing the chromosome inhibiting ribosomes depolarizing plasma membranes

forming pores depolarizing plasma membranes

Microbes that provide the host with a suite of activities required for health and homeostasis are termed the _____. gut microbiome functional core microbiome functional core metabolome healthy microbiome

functional core microbiome

Which of the following statements reflects current thinking about the microbiota of the respiratory tract? The lower respiratory tract is not sterile. The lower respiratory tract is colonized by a diverse group of microbes. Both upper and lower respiratory tracts host similar communities of microbes.

he lower respiratory tract is not sterile.

B cells that differentiate into secretory IgA-producing plasma cells are located _____. in the lumen of the gut in the gut-associated lymphoid tissue throughout the bloodstream in the bone marrow

in the gut-associated lymphoid tissue

Both mice and humans exhibit which two of the following changes in the gut microbiota in obesity? increased Firmicutes elimination of Clostridium increased fungi decreased Bacteriodetes increased Escherichia

increased Firmicutes decreased Bacteriodetes

Propionate is formed as a fermentation product of the gut microbiota. Its two roles in metabolism are to _____ and _____. act as a precursor for lipid synthesis inhibit cholesterol synthesis in the liver stimulate secretion of enzymes to hydrolyze polysaccharide increase colonocyte mitochondrial activity increase synthesis of hunger-suppressing hormones

inhibit cholesterol synthesis in the liver increase synthesis of hunger-suppressing hormones

Two challenges to the use of probiotics to treat humans are that _____ and _____. they cannot be consumed by people with lactose intolerance most probiotic organisms cannot be cultured in the lab it is difficult to evaluate whether probiotics colonize the gut the health benefits have not been rigorously tested

it is difficult to evaluate whether probiotics colonize the gut the health benefits have not been rigorously tested

Metabolic endotoxemia refers to a change in the diet that leads to dysbiosis and the presence of _____ to the blood. pro-inflammatory cytokines short chain fatty acids bacteriocins lipopolysaccharide

lipopolysaccharide

Germ-free mice exhibit anatomic differences in tissues other than in the gut, specifically in the _____, where these tissues were underdeveloped. [Choose three.] urinary tract lymph nodes thyroid spleen thymus meninges

lymph nodes spleen thymus

A dietary change that leads to dysbiosis and the presence of lipopolysaccharide to the blood results in a series of events termed _____. Multiple choice question. musocal immunity metabolic endotoxemia insulin resistance atherosclerosis

metabolic endotoxemia

The biochemicals secreted by bacteria in the gut that act on host cells are collectively termed the _____. metabolome transcriptome metagenome microbiome

metabolome

The biochemicals secreted by bacteria in the gut that act on host cells are collectively termed the _____. transcriptome metagenome metabolome microbiome

metabolome

The term used to describe all the microbes that reside in and on a healthy host is _____. microbiome microgenome microassociation community

microbiome

Toxic peptides produced by some bacteria that kill closely related strains are termed _____ if they are made by a wide range of Enterobacteriaceae and _____ if they are produced by E. coli. bacteriocins; colicins colicins; microcins bacteriocins; microcins microcins; colicins

microcins; colicins

The idea that we can host so many microbes and foreign food antigens in our gut without responding with an overwhelming inflammatory response is termed _____. immune surveillance mucosal tolerance probiotic tolerance colonization resistance

mucosal tolerance

In a healthy human, which of the following tissues is normally colonized by microorganisms? muscles cerebrospinal fluid mucous membranes blood

mucous membranes

In a healthy human, which of the following tissues is normally free of microorganisms? mucous membranes skin muscles gut

muscles

Microbes commonly associated with the human body are known as __________ microbiota.

normal

Microbes commonly associated with the human body are known as _____. normal microbiota metagenomes contaminants opportunistic microbes

normal microbiota

An increased concentration of Firmicutes and a decreased concentration of Bacteroidetes in the gut is often correlated with _____. a vegan diet weight loss obesity viral infection

obesity

Bacteria in the gut secrete enzymes to break down _____, which are then fermented into short-chain fatty acids like butyrate, propionate, and acetate. complex proteins to amino acids long-chain hydrocarbons to acetyl CoA milk proteins to simple sugars polysaccharides to monomers

polysaccharides to monomers

Compounds added to foods or supplements to enhance the colonization and health benefits of other microorganisms are termed __________.

prebiotic

Certain human viruses cause their host cells to become cancerous by which two mechanisms? preventing DNA damage repair altering the host cell cycle altering nuclear import signals generalized transduction generating reactive oxygen species in the viroplasm

preventing DNA damage repair altering the host cell cycle

Live microorganisms, which when administered in adequate amounts confer a health benefit to the host, are termed ______.

probiotic

Live microorganisms, which when administered in adequate amounts confer a health benefit to the host, are termed _____. synbiotics prebiotics probiotics

probiotics

Breastfeeding is important in the development of an infant's intestinal microbiota because human milk _____. promotes growth of bifidobacteria inhibits growth of viral pathogens promotes growth of firmicutes is transferred to the baby anaerobically

promotes growth of bifidobacteria

Following fermentation of carbohydrate monomers, the short-chain fatty acid _____ travels to the liver where it inhibits cholesterol synthesis. acetate lactate butyrate propionate

propionate

Classifying certain probiotics as drugs has the consequence of _____. requiring pure cultures with sequenced genomes creating competition among probiotic producers requiring safety and efficacy clinical trials requiring that they be available only by prescription

requiring safety and efficacy clinical trials

Immune cell maturation requires _____ produced by the gut microbiota as well as cytokines released by intestinal immune cells. MAMPs short chain fatty acids secondary bile salts amphipathic peptides

short chain fatty acids

Bacteria in the gut secrete enzymes to break down complex polysaccharides into their constituent monomers. These monomers are then fermented into _____. ethanol (alcohol) short-chain fatty acids lactate hydrogen and CO2

short-chain fatty acids

Foods or supplements that include both live microorganisms, which when administered in adequate amounts confer a health benefit to the host, and compounds to enhance the colonization of the GI tract are termed _____. probiotics prebiotics synbiotics

synbiotics

Microcins and colicins can inhibit which three of the following? tRNA synthetase cell wall synthesis nitrogen fixation RNA polymerase topoisomerases detoxifying reactive oxygen species

tRNA synthetase cell wall synthesis RNA polymerase

In the gut, the growth of anaerobes is favored over facultative anaerobes by _____. colicin production microcin production the low oxygen tension sensitivity to killing by C-type lectins

the low oxygen tension

The metabolome is best described as _____. the metabolic products secreted by bacteria host biochemicals and hormones that affect the gut microbiome metabolism host biochemicals and hormones that affect the composition of the functional core microbiome

the metabolic products secreted by bacteria

Colonization resistance refers to the idea that _____. the microbiota in the gut is protected from disease by the presence of a healthy community pathogens cannot establish themselves in the gut in the presence of antibiotics once the gut microbiome is established in an infant, it cannot be changed substantively

the microbiota in the gut is protected from disease by the presence of a healthy community

Babies born vaginally acquire most of their initial microbiota from _____. hospital workers the hospital environment their mother microbes in the air

their mother

Animals that eat a meat-intensive diet introduce L-carnitine and phosphatidylcholine to their GI tract, where microbial metabolism converts them to _____. reactive oxygen species trimethylamine serotonin amino acids

trimethylamine

Some Gram-negative bacteria deliver bacteriocidal toxins directly through the cell envelope of competing bacteria through their _____. membrane vesicles type VI secretion system conjugative pili type III secretion system

type VI secretion system

Germ-free mice exhibit anatomic differences in tissues other than in the gut, specifically in the spleen, thymus, and lymph nodes, where these tissues were _____. underdeveloped enlarged absent cancerous

underdeveloped

Select all that apply In addition to bacteria, which three of the following are also present in the human microbiome? water molds viruses archaea algae fungi viroids

viruses archaea fungi

Mucosal tolerance explains how _____. we can host many microbes and foreign food antigens in our gut without responding with an overwhelming inflammatory response the microbiota in the gut is protected from disease by the presence of a healthy community the microbiota in the gut is at least partially responsible for the development of the innate immune system

we can host many microbes and foreign food antigens in our gut without responding with an overwhelming inflammatory response

Germ-free mice have limited development of the _____ cells of the innate immune system. stem white blood red blood B

white blood


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