Deck 27: Environmental and Food Microbiology

Question 1

Which of the following relationships is shown in this soil food web?

A) Vertebrate animals are consumed by birds.
B) Some nematodes consume fungi and bacteria.
C) Fungi utilize carbon dioxide produced by plants.
D) Bacteria consume protozoa.

Answer 1

B

Question 2

The figure shown indicates a dead zone within the Gulf of Mexico.Which of the following would you expect to find in the area labeled "Lower Mississippi"?

A) an increase in the number of fish and invertebrates
B) a decrease in algal growth within the Mississippi River and tributaries
C) an increase in photosynthetic bacteria
D) an increase in nitrates from agricultural fertilizers

Answer 2

D

Question 3

A high school student visiting Lake Erie reads a sign indicating that it is unsafe to swim at a beach because of a toxin called microcystin.The student does some research and finds the following relationship between fertilizer,algae,heterotrophic bacteria,and fish: fertilizer runoff causes

A) algal blooms, which lead to an increase in heterotrophic bacteria and a decrease in fish.
B) increases in heterotrophic bacteria, which leads to an increase in algal blooms and a decrease in fish.
C) increases in fish populations, which leads to decreases in heterotrophic bacteria and algae populations.
D) algal blooms, which lead to a decrease in heterotrophic bacteria and an increase in fish.

Answer 3

A

Question 4

A microbe's contribution to an ecosystem's health depends on the

A) microbe's genome and the physical and chemical characteristics of the environment.
B) microbe's age and number of primary producers in the environment.
C) microbe's ability to cycle carbon and the number of decomposers in the ecosystem.
D) bioremediation capacity of the microbe and the number of predators in the ecosystem.

Question 5

If bacteria and archaea are removed from an ecosystem,which of the following environmental services would be absent?

A) nitrogen fixation
B) capture of energy from sunlight
C) decomposition of dead matter
D) dissimilation of biomass by respiration

Question 6

The figure provided shows a food web.Which of the following statements is true?

A) Ten percent of the carbon dioxide fixed by grazers is used by decomposers.
B) Ten percent of the carbon dioxide fixed by primary producers is used by predators.
C) Ninety-nine percent of the carbon dioxide fixed by primary producers is lost by the second trophic level.
D) Grazers consume ten percent of the decomposers.

Question 7

The largest population of fermenters is found in the chamber labeled

A) A
B) B
C) C
D) D

Question 8

Which of the following occurs as a result of using common bread mold to ferment soybeans during the production of tempeh?

A) Phytate is introduced.
B) Lectins are decreased.
C) Protein content is increased.
D) Autoimmune diseases are induced.

Question 9

Which of the following statements correctly describes the relationship between biochemical oxygen demand (BOD),heterotrophic bacteria,and fish?

A) The presence of fish increases the number of heterotrophic bacteria in an area, which decreases the BOD.
B) Increases in the number of heterotrophic bacteria decrease the BOD, which decreases the number of fish.
C) The BOD of a marine environment is independent of populations of heterotrophic bacteria and fish.
D) Heterotrophic bacteria generate oxygen, which increases the BOD and increases the number of fish.

Question 10

An obligate association exists between a gut microbe and an insect.A new mutation in the microbe allows the microbe to utilize nutrients that were previously accessible to the insect.This change benefits the microbe,but causes some harm to the insect.The change in the relationship is best described as a change from

A) mutualism to parasitism.
B) synergism to parasitism.
C) commensalism to amensalism.
D) parasitism to synergism.

Question 11

A commonality of bread,cheese,beer,and chocolate is the use of ________ in their production.

A) anaerobic fermentation
B) lactic acid bacteria
C) acetic acid bacteria
D) highly engineered microbial strains

Question 12

During alcoholic fermentation of grains,hops plays a role in providing

A) sugar for ethanol production.
B) enzymes to break down starch.
C) antibacterial properties to extend the shelf life of beer.
D) the flavor of wines.

Question 13

Which of the following statements describes the relationship between physical factors and the ability of microbes to grow?

A) Most microbes survive best at normal human body temperature.
B) Different microbial species are able to survive different physical conditions.
C) All microbes require oxygen for growth.
D) Microbial growth is not influenced by physical factors.

Question 14

Bacteriocins are molecules that are produced by

A) some bacteria and prevent pathogens from adhering to the gut lining.
B) methanogens and cause flatulence in cows.
C) digestive microbes in termites and allow digestion of cellulose.
D) viruses and increase the virulence of zoonotic diseases.

Question 15

Shifting a cow's diet results in a(n)

A) change in the pathway of digestion through the cow's four stomach chambers.
B) change in the microbial populations present within the cow's gut.
C) increase in antibiotic-resistant bacteria found in the environment.
D) decrease in the amount of water and short-chain acids absorbed in the omasum.

Question 16

High salt concentrations limit the growth of microbes adapted to freshwater conditions because

A) salt prevents microbes from using oxygen as an electron acceptor during aerobic cellular respiration.
B) high salt concentrations increase the temperature of the environment above the range at which most microbes can survive.
C) freshwater is a hypotonic solution and microbes living in freshwater do not have a need for mechanisms to reduce water loss.
D) a high salt concentration leads to a sharp decline in the pH of the environment.

Question 17

Which of the following illustrates a positive interaction between human microbiota and the immune system?

A) down-regulation of cytokines within the colon
B) production of short-chain acids within the colon
C) conversion of hydrogen gas and carbon dioxide into methane
D) secretion of acids that decrease pH within the colon

Question 18

A new species of human gut bacteria is discovered.Scientists find that during the process of breaking down and utilizing undigested plant fibers,the bacteria also produces a vitamin that is absorbed by humans.The relationship described is an example of

A) amensalism.
B) parasitism.
C) commensalism.
D) mutualism.

Question 19

Which of the following molecules is converted to ethanol in the production of beer?

A) aldehydes
B) long-chain alcohols
C) maltose
D) fatty acids

Question 20

Although beer and wine are both produced through ethanolic fermentation,there are some differences in the pathway.Which of the following illustrates one of these differences?

A) Wine production involves the breakdown of long-chain carbohydrates.
B) Wine is produced from simple sugars.
C) Only beer production involves pyruvate as an intermediate.
D) Only wine production can lead to the production of diacetyl.

Question 21

What is the most available carbon-based nutrient in milk that is used by microbes during anaerobic fermentation?

A) lactose
B) glucose
C) protein
D) fat

Question 22

Dehydrating foods and freezing foods both work well to preserve foods because they

A) make water unavailable to microbes.
B) both involve low temperatures.
C) kill microbes.
D) remove nutrients used by microbes.

Question 23

What role do microbes play in the increase of atmospheric carbon dioxide seen in this graph?

A) Microbial populations have been increasing since 1800, and this increase has led to increases in carbon dioxide levels.
B) Microbes convert other elements in carbon dioxide and have caused increases in carbon dioxide levels.
C) Microbial populations have been decreasing since 1800, and this decrease has led to increases in carbon dioxide levels.
D) Microbes fix carbon dioxide and help limit increases of carbon dioxide in the atmosphere.

Question 24

Historically,N₂ only entered the atmosphere as a result of nitrogen fixation by bacteria and archaea.How has human technology affected nitrogen cycling?

A) Humans genetically modified plants to allow them to fix nitrogen.
B) Humans developed a method for artificially fixing nitrogen to generate fertilizers.
C) Humans use nitrogen as a source of renewable energy.
D) Human technology has had no effect on nitrogen cycling.

Question 25

Historically,there has been concern about the ingestion of nitrite used as a food preservative.Why does nitrite work well as a food preservative?

A) Nitrites are used to inhibit aerobic respiration of bacteria.
B) Nitrites increase carbon dioxide levels.
C) Nitrites have antimicrobial properties.
D) Nitrites cross cell membranes and release protons intracellularly.

Question 26

One benefit of food fermentation is the generation of vitamin

A) A.
B) C.
C) B₁₂.
D) D.

Question 27

Of the following physical means of preserving foods,the only method capable of destroying endospores is

A) pasteurization.
B) canning.
C) dehydration.
D) decreased oxygen.

Question 28

Spoilage of food can alter the odor or taste of the food.Which of the following statements correctly matches a pathway to the spoilage that results?

A) Acidic fermentation leads to a bitter flavor.
B) Alkaline products from microbial metabolism leads to a sour flavor.
C) Oxidation of fats leads to rancidity.
D) Decomposition of proteins and amino acids leads to a salty flavor.

Question 29

Photosynthesis in microbes converts carbon dioxide into

A) biomass.
B) carbonate rock.
C) ethanol.
D) nitrosamine.

Question 30

Curds from milk fermentation are particularly valuable because they

A) are a source of concentrated protein.
B) contain more vitamins than milk.
C) contain acetic acid that can be used to preserve other foods.
D) have an indefinite shelf life and do not require refrigeration.

Question 31

A grocery store chain wants to respond to consumer demands to reduce the use of Styrofoam trays and plastic wrap used in vacuum-packed food packages.In which of the following foods will food quality be most affected by a reduction in the use of vacuum packages?

A) ground beef
B) pork chops
C) cheese
D) fresh herbs

Question 32

When comparing the line representing bacterial growth at 6°C to the line representing growth of organisms at 4°C,which of the following is true?

A) More growth occurs at 4°C.
B) The rate of growth is lower at 6°C.
C) There were preexisting contaminants in both cases.
D) On day 10 the population at 4°C was half of the population at 6°C.

Question 33

What is the function of aeration basins at wastewater treatment facilities?

A) Aeration encourages fermentation.
B) Aeration maximizes microbial breakdown of pollutants to carbon dioxide and nitrates.
C) Aeration limits free-floating populations of bacteria.
D) Aeration allows filamentous methanogens to metabolize acetate within the interior of flocs.

Question 34

A chicken producer in Georgia is considering installing a wetland rather than a traditional wastewater treatment facility to handle chicken manure and wastewater.Which of the following is an advantage of using a wetland?

A) Wetlands do not contain microbes.
B) Wetlands produce fewer odors than wastewater treatment facilities.
C) The cost of a wetland is only slightly higher than the cost of a wastewater treatment facility.
D) Wetlands do not take up much space.

Question 35

Chantel becomes seriously ill with diarrhea and vomiting after eating some potato salad.Upon questioning she states that there was no off odor and the potato salad tasted fine.Which of the following is the most likely explanation for her illness?

A) Enzymatic processes that began occurring after the potatoes were harvested led to her illness.
B) Oxidation by air converted some of the lipids in the potato salad into rancid products.
C) Acidic fermentation by microbes affected the pH of the potato salad, which made her ill.
D) A small number of pathogens caused food contamination.

Question 36

Human sewage and industrial effluents are abundant in

A) short-chain fatty acids and urea.
B) monosaccharides and insoluble fiber.
C) amino acids and urea.
D) amino acids and insoluble fiber.

Question 37

The fixed form of nitrogen (ammonium ion and ammonia)can be oxidized for energy by

A) methanogens.
B) nitrifiers.
C) lithotrophs.
D) fermenters.

Question 38

This figure shows restriction-digested DNA fragments from Salmonella enterica that have been separated by electrophoresis.The Salmonella enterica was isolated from individuals with illness and two jars of peanut butter.Which of the following accurately describes these fragments?

A) These fragments indicate food contamination in both jars of peanut butter.
B) These fragments indicate no relationship between the ill individuals and peanut butter.
C) These fragments indicate that individuals became ill after eating peanut butter from Jar 2.
D) These fragments indicate food contamination in Jar 1, but not in Jar 2.

Question 39

A wastewater treatment facility experiences a massive die-off of anaerobic bacteria.How will this die-off affect the treatment process?

A) Primary treatment will be affected.
B) Tertiary treatment will be affected.
C) Secondary treatment will be affected.
D) Treatment will not be affected because the microbial ecosystem is normally aerobic.

Question 40

When carbon- and nitrogen-rich wastes are released into aquatic environments

A) algae populations decrease.
B) fish populations increase.
C) invertebrate populations increase.
D) bacterial populations increase.

Question 41

Your sister leaves the milk out on the counter after breakfast one day.Eight hours later she realizes her mistake and puts the milk back in the refrigerator.The next morning she pours herself a glass of milk,takes a sip of the milk,and immediately spits it out.Was she responding to food spoilage or food contamination? Explain your reasoning.

Question 42

During the production of beer,fermentation produces ethanol and the gas ________.

Question 43

The specialized relationship in which one member benefits while the other member is harmed is known as ________.

Question 44

Explain the location of the "dead zone" shown in this figure.What causes this dead zone to appear annually during spring?

Question 45

Describe the carbon reservoir that cycles the most carbon through living bodies on Earth.

Question 46

Describe any differences between the primary producers in the ocean versus the primary producers on land.

Question 47

Explain the pattern of groundwater nitrate contamination risk shown in this map.

Question 48

In a wastewater treatment plant,the removal of large,solid debris such as sticks and dead animals occurs during ________ treatment.

Question 49

List two ways in which food fermentation benefits humans and provide one example for each.

Question 50

Organic molecules in lake water are consumed as food and combined with oxygen by ________.

Question 51

Describe how bacteria such as Lactobacillus species are used to produce yogurt.

Question 52

CASE HISTORY
In the fall of 2008,several individuals,many of them children,were sickened from the common food pathogen Salmonella enterica.Most infected individuals developed diarrhea,fever,and abdominal cramps 12-72 hours after infection,and symptoms lasted 4-7 days.Over the next six months,cases were reported from nearly all U.S.states,ultimately totaling 700 people.The curve of the outbreak (cases rising and then falling)followed the profile of a single-source epidemic,in which all infections are ultimately traced to one source.All cases of illness showed a common strain of the pathogen S.enterica serovar typhimurium.CDC researchers investigated the outbreak by comparing the food intake histories of ill persons with that of matched controls.They found a statistical association between illness and intake of peanut butter,eventually narrowed to a specific brand of peanut butter sold to institutions.As the epidemic grew,cases emerged in which the contaminated food product turned out to be crackers filled with peanut butter cream.Ultimately,the peanut butter and cream were traced back to peanuts from a single factory in Georgia.
Which best describes this outbreak of foodborne illness?

A) It is an example of food spoilage.
B) It is an example of a point-source epidemic.
C) The origin of the outbreak is contamination of the peanut butter by a plant pathogen.
D) If carefully examined, the peanut butter would have been noticeably "off " in taste, smell, texture, or other observable characteristics.

Question 53

What are the three factors that control the ways in which food spoils?

Question 54

Bacteria and archaea are the only organisms capable of converting the element ________ between its oxidation states.

Question 55

Moving microbes from the gut of a healthy person into a diseased colon to return normal function in a patient with recurrent Clostridium difficile infections is known as ________.

Question 56

Using organisms such as bacteria to neutralize pollutants from a contaminated site is referred to as ________.

Question 57

An end result of mixed-acid fermentation products being converted into a gas in cattle is production of the greenhouse gas ________.

Question 58

Explain how the availability of oxygen in soil determines how microbes utilize organic compounds supplied by other organisms.

Question 59

Bacteria,such as Listeria monocytogenes,that are able to grow at refrigeration temperatures are referred to as ________.

Question 60

Carbon dioxide in the atmosphere traps solar heat in a process known as the ________.

Question 61

CASE HISTORY
In 1994,the city of Phoenix,Arizona,faced challenges to its water supply.In a desert,water is scarce,and quality is hard to maintain.The city's water department needed to decrease its wastewater's organic nitrogen content,which threatened the river downstream.A study proposed the construction of a wetland environment to receive the treated effluent from the Phoenix sewage plant.Over the next ten years,the city constructed a series of experimental wetlands,leading to the large-scale tres rios-constructed Wetlands Project.By 2010,the constructed wetland encompassed 800 acres and filtered 170 million gallons per day.Besides controlling nitrogen and organic content,the wetland restores groundwater,offers a carbon offset (net CO₂ removed from the atmosphere),and generates a wildlife-rich recreational area.The tres rios wetland now attracts beavers,bald eagles,and bobcats,as well as many human visitors.
Why might many different configurations of wetland have been constructed in order to achieve the desired microbial community and effect?

Question 62

CASE HISTORY
In the fall of 2008,several individuals,many of them children,were sickened from the common food pathogen Salmonella enterica.Most infected individuals developed diarrhea,fever,and abdominal cramps 12-72 hours after infection,and symptoms lasted 4-7 days.Over the next six months,cases were reported from nearly all U.S.states,ultimately totaling 700 people.The curve of the outbreak (cases rising and then falling)followed the profile of a single-source epidemic,in which all infections are ultimately traced to one source.All cases of illness showed a common strain of the pathogen S.enterica serovar typhimurium.CDC researchers investigated the outbreak by comparing the food intake histories of ill persons with that of matched controls.They found a statistical association between illness and intake of peanut butter,eventually narrowed to a specific brand of peanut butter sold to institutions.As the epidemic grew,cases emerged in which the contaminated food product turned out to be crackers filled with peanut butter cream.Ultimately,the peanut butter and cream were traced back to peanuts from a single factory in Georgia.
Describe some of the chemical and physical approaches normally used in the production and storage of a food like peanut butter,which are designed to reduce the possibility of outbreaks such as this one.Give an example of a common scenario in which these precautions might fail.