Question 1

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

Accepted Answer

Lactose is the most available carbon-based nutrient in milk that is used by microbes during anaerobic fermentation. Lactose is a disaccharide composed of glucose and galactose and is the primary sugar found in milk.

Question 2

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

Accepted Answer

Both dehydrating foods and freezing foods remove the water that microbes need to grow and reproduce, making it unavailable to them and preserving the food. However, freezing does not necessarily kill all microbes, while dehydrating at high enough temperatures can actually kill them. Additionally, neither method necessarily removes nutrients that microbes would use, making choice D incorrect. Therefore, A is the best choice.

Question 3

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

Accepted Answer

The answer of What role do microbes play in the...

Question 4

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

Accepted Answer

Human technology has led to the ability to artificially fix nitrogen, which has allowed for the production of synthetic fertilizers. This has significantly increased the availability of nitrogen for plant growth, which has led to higher crop yields and increased food production. However, this increased use of fertilizers also contributes to environmental issues such as eutrophication and greenhouse gas emissions.

Question 5

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

Accepted Answer

The answer of Historically,there has been concern about the ingestion...

Question 6

One benefit of food fermentation is the generation of vitamin

Accepted Answer

Fermentation can lead to the production of vitamin B₁₂, especially in fermented foods like certain types of fermented soy products and dairy.

Question 7

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

Accepted Answer

Endospores are highly resistant structures formed by some bacterial species that allow them to survive harsh conditions. Canning is the only method among the options given that involves high heat and pressure, which is capable of destroying endospores. Pasteurization does not reach the temperatures necessary to destroy endospores, dehydration and decreased oxygen do not have any effect on endospores.

Question 8

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?

Accepted Answer

The oxidation of fats can lead to rancidity, which alters the taste and odor of the food. Option A is incorrect because acidic fermentation can result in a sour flavor, not a bitter one. Option B is incorrect because alkaline products from microbial metabolism often lead to a bitter flavor, not a sour one. Option D is incorrect because the decomposition of proteins and amino acids can lead to a putrid flavor, not a salty one.

Question 9

Photosynthesis in microbes converts carbon dioxide into

Accepted Answer

Photosynthesis in microbes is the process of converting carbon dioxide and water into organic compounds, specifically biomass, by using sunlight as an energy source. Therefore, among the given options, A is the correct answer. B and D are not related to photosynthesis, and C is the product of fermentation, not photosynthesis.

Question 10

Curds from milk fermentation are particularly valuable because they

Accepted Answer

Curds from milk fermentation are high in protein, which is concentrated during the fermentation process. They are often used as a source of protein in many diets, making them particularly valuable. The other choices are not entirely accurate, as curds do not necessarily contain more vitamins than milk, contain acetic acid for food preservation, or have an indefinite shelf life without refrigeration.

Question 11

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?

Accepted Answer

The answer of A grocery store chain wants to respond...

Question 12

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?

Accepted Answer

The answer of When comparing the line representing bacterial growth...

Question 13

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

Accepted Answer

Aeration basins provide oxygen to support the growth and metabolism of aerobic bacteria that break down organic matter in the wastewater. The microbes use the oxygen to convert pollutants to carbon dioxide and nitrates, which can be removed from the wastewater. The aeration process also helps to mix the wastewater and bacteria, improving the effectiveness of the treatment.

Question 14

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?

Accepted Answer

Wetlands use natural processes to remove pollutants and impurities from wastewater and chicken manure, producing fewer odors than traditional wastewater treatment facilities. Wetlands also provide habitat for wildlife and have a lower carbon footprint than traditional wastewater treatment facilities. While the initial cost of installing a wetland may be slightly higher than a traditional wastewater treatment facility, the maintenance costs are generally lower in the long run. A wetland may require more space than a traditional wastewater treatment facility, but it can also serve a dual purpose as a wildlife habitat. Wetlands do contain microbes, which are essential in breaking down pollutants and organic matter.

Question 15

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?

Accepted Answer

The symptoms of diarrhea and vomiting indicate a potential foodborne illness, which is commonly caused by the ingestion of pathogens such as bacteria, viruses, or parasites. It is possible that a small number of these pathogens contaminated the potato salad, leading to Chantel's illness. The absence of off odor or taste does not necessarily rule out the presence of pathogens, as certain types can cause illness without affecting the appearance, odor, or flavor of the food.

Question 16

Human sewage and industrial effluents are abundant in

Accepted Answer

Human sewage and industrial effluents are abundant in short-chain fatty acids and urea. Short-chain fatty acids are produced by the anaerobic fermentation of organic matter, while urea is a waste product of protein metabolism.

Question 17

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

Accepted Answer

Nitrifiers are the organisms that can oxidize the fixed form of nitrogen (ammonium ion and ammonia) for energy. They are chemolithotrophs, which means they obtain energy from inorganic compounds. Nitrification is the process by which ammonium ion is first oxidized to nitrite and then to nitrate by nitrifying bacteria. This process releases energy that is used by the bacteria for growth and reproduction.

Question 18

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?

Accepted Answer

The answer of This figure shows restriction-digested DNA fragments from...

Question 19

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

Accepted Answer

The secondary treatment process heavily relies on anaerobic bacteria to break down organic matter in the wastewater. Therefore, a massive die-off of anaerobic bacteria will have a significant impact on the efficiency of the secondary treatment process.

Question 20

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

Accepted Answer

When carbon- and nitrogen-rich wastes are released into aquatic environments, bacterial populations increase as they feed on the organic matter and decompose it. This can lead to a decrease in oxygen levels in the water, creating dead zones where fish and invertebrate populations may suffer.

Quiz 27: Environmental and Food Microbiology