Microbiology Test Questions!

Biogas is a type of gas produced from the decomposition of organic matter in the absence of oxygen. It primarily consists of methane, along with small amounts of other gases such as carbon dioxide and traces of hydrogen sulfide. Methane is the main component of biogas, typically accounting for 50-75% of its composition. Methy Acetate and Methanol are not typically found in significant amounts in biogas. Therefore, the correct answer is methane.

Malting is a step in beer production that involves the germination of barley grains. During germination, enzymes are produced to break down starches in the barley into fermentable sugars. The enzyme responsible for this process is amylase. Amylase catalyzes the hydrolysis of starch into smaller sugar molecules, such as maltose, which can be fermented by yeast to produce alcohol during the brewing process. Therefore, amylase is the natural enzyme utilized during malting for beer production.

Autoclaving is a process used to sterilize equipment and materials by using high-pressure steam. The temperature reached in autoclaving is typically around 120 degrees Celsius. This high temperature helps to kill bacteria, viruses, and other microorganisms, ensuring that the items being sterilized are safe for use in medical, laboratory, or other settings where sterility is crucial.

Mycoprotein is a food source that is rich in protein and very low in fat. This means that it provides a significant amount of protein, which is essential for building and repairing tissues, while containing minimal fat content. This makes mycoprotein a healthy choice for individuals looking to increase their protein intake without consuming excessive amounts of fat.

Aerobic respiration in animals releases the most energy when one molecule of glucose is respired. This process occurs in the presence of oxygen and involves the complete breakdown of glucose, resulting in the production of a large amount of ATP (adenosine triphosphate), the energy currency of cells. Anaerobic respiration in yeast and anaerobic respiration in animals do not require oxygen and produce less ATP compared to aerobic respiration.

Concrete is used to line biogas fermenters because it has the ability to resist the build-up of pressure. Biogas fermenters produce biogas through the anaerobic digestion of organic materials. This process generates a significant amount of pressure within the fermenter. By lining the fermenter with concrete, it provides a strong and durable barrier that can withstand the pressure exerted by the biogas. Additionally, concrete is not easily corroded, making it a suitable material for long-term use in this application. Its availability and relatively low cost also contribute to its suitability for lining biogas fermenters.

Microbe respiration is the correct answer because respiration is the process by which microorganisms convert organic compounds into energy. In a fermenter, microorganisms break down the organic materials through respiration, releasing heat as a byproduct. This heat helps to maintain the optimal temperature for the growth and activity of the microorganisms in the fermenter. Microbe reproduction and digestion are not directly related to the generation of heat in a fermenter.

Moulds are organisms that produce antibiotics. Antibiotics are natural compounds produced by certain microorganisms to inhibit the growth of other microorganisms. Moulds, such as Penicillium, produce antibiotics like penicillin. Animal cells do not have the capability to produce antibiotics, while yeast is not typically known for producing antibiotics. Therefore, moulds are the correct answer as they are known to produce antibiotics.

Lactose is the correct answer because it is the main substrate used in the production of yogurt. Lactose is a disaccharide found in milk, and it serves as the primary source of energy for the bacteria used in the fermentation process to produce yogurt. During fermentation, the bacteria break down lactose into lactic acid, which gives yogurt its tangy taste and thick texture. Therefore, lactose is essential for the production of yogurt.

Biogas is a useful source of energy as it can be used for heating, cooking, and electricity generation. It is produced by the anaerobic digestion of organic waste materials such as agricultural residues, food waste, and sewage sludge. In addition to energy generation, biogas production also results in the production of a type of fertilizer called digestate. Digestate is a nutrient-rich byproduct of the anaerobic digestion process and can be used as a natural fertilizer to improve soil fertility and crop yields. Therefore, the production of biogas generates both energy and a type of fertilizer, making it a useful source of energy.

Biogas fermenters are buried to protect the microbes involved in the fermentation process. By burying the fermenters, the microbes are shielded from extreme temperature variations, sunlight, and other environmental factors that could potentially harm or disrupt their activity. This protection ensures that the microbes can continue to efficiently break down organic matter and produce biogas without any detrimental effects.

Aerobic respiration by yeast and anaerobic respiration by yeast differ in terms of the byproducts they produce. While both processes release energy, only anaerobic respiration produces ethanol as a byproduct. Aerobic respiration, on the other hand, produces carbon dioxide as a byproduct.

Biofuels, particularly those derived from crops like maize, can lead to overproduction of these crops. This overproduction can have negative consequences such as increased deforestation, excessive use of water resources, and disruption of ecosystems. Additionally, focusing solely on biofuels can divert resources and attention away from other renewable energy sources that may have less detrimental effects on agriculture and the environment.

Washing hands before handling microbes is considered good practice because it helps prevent the growth of unknown microbes. By washing hands, any potential harmful microbes present on the hands can be removed, reducing the risk of contamination. This is particularly important when working with microbes, as they can easily spread and cause infections or other negative effects. Washing hands before handling microbes helps maintain a clean and safe environment, minimizing the chances of introducing unknown microbes into the surroundings.

A cooling jacket of water surrounding a fermenter can be used to increase the temperature of the liquid in a fermenter. By circulating cold water through the jacket, heat from the fermentation process can be absorbed, effectively raising the temperature of the liquid inside the fermenter. This can be useful in certain fermentation processes that require a higher temperature for optimal microbial growth and product formation.

Rotating blades inside a fermenter serve various purposes, such as circulating the mixture and removing areas of excess heat. However, the statement "It introduces oxygen into the mixture" is not a reason for the use of rotating blades. In fact, in certain fermentation processes, the presence of oxygen can be detrimental. Therefore, the use of rotating blades in a fermenter is not intended to introduce oxygen into the mixture.

Cellulose cell wall is not found in yeast cells and plant cells. Yeast cells have a cell wall composed of glucans and mannan, while plant cells have a cell wall composed of cellulose, hemicellulose, and pectin. The cell wall provides structural support and protection to the cell. Cell membranes and vacuoles are present in both yeast cells and plant cells. The cell membrane controls the movement of substances in and out of the cell, while vacuoles store water, nutrients, and waste materials.

In cheese production, milk is thickened by the activity of enzymes. Enzymes, such as rennet, are added to the milk to coagulate it, causing the proteins to curdle and form a solid mass. This process is essential for cheese-making as it helps to separate the curds from the whey. In contrast, in yoghurt production, milk is thickened when it is incubated with bacteria. The bacteria ferment the lactose in the milk, producing lactic acid, which causes the milk to thicken and form yoghurt.

Yeast plays a crucial role in the complete process of wine fermentation. It carries out both aerobic and anaerobic respiration. Initially, in the presence of oxygen, yeast undergoes aerobic respiration, converting sugar into carbon dioxide and water. As the oxygen supply depletes, yeast switches to anaerobic respiration, converting sugar into alcohol and carbon dioxide. This dual process of respiration by yeast is essential for the production of wine.

When protein nutrients are in short supply, bacteria tend to produce antibiotics in order to compete with other microorganisms for limited resources. This is a survival mechanism for bacteria to ensure their own growth and inhibit the growth of other organisms. The production of antibiotics is a response to the stress caused by the scarcity of protein nutrients, allowing bacteria to have a competitive advantage in their environment.