Microbial Nutrition Quiz
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Questions and Answers

Which of the following best describes inorganic nutrients?

  • Products of metabolic processes in organisms.
  • Large complex structures made from living organisms.
  • Atoms or simple molecules containing a combination of atoms other than carbon. (correct)
  • Molecules primarily consisting of carbon and oxygen.

What characterizes organic nutrients in microbial nutrition?

  • They are exclusively composed of carbon without any hydrogen.
  • They contain components primarily sourced from inorganic minerals.
  • They include simple molecules and large polymers that contain carbon and hydrogen. (correct)
  • They are produced solely by chemical reactions in non-living systems.

Which of the following statements accurately describes essential nutrients?

  • They can be synthesized by the organism from simple raw materials.
  • They must be provided externally as they are critical for growth. (correct)
  • They are not necessary for the basic functions of the organism.
  • They are only found in organic compounds derived from other organisms.

Which of the following is NOT considered an example of organic nutrients?

<p>Nitrogen gas (B)</p> Signup and view all the answers

What is a distinguishing feature of inorganic nutrients in relation to their sources?

<p>They are commonly found in the atmosphere, crust of the Earth, and bodies of water. (C)</p> Signup and view all the answers

Which type of heterotroph derives nutrients from the cells or tissues of a living host?

<p>Pathogen (B)</p> Signup and view all the answers

What type of interaction occurs when different species compete in a community for resources?

<p>Antagonism (C)</p> Signup and view all the answers

What is the main function of saprobes in the ecosystem?

<p>To decompose organic matter (C)</p> Signup and view all the answers

What is a crucial process used by bacteria in biofilms to communicate with each other?

<p>Quorum sensing (A)</p> Signup and view all the answers

Which of the following nutrients is essential for stabilizing cell walls and endospores of bacteria?

<p>Calcium (C)</p> Signup and view all the answers

Which of the following best describes the structure of biofilms?

<p>Large, complex communities with varying pH and oxygen conditions (A)</p> Signup and view all the answers

What defines a chemoheterotroph?

<p>An organism that obtains both energy and carbon from organic compounds (C)</p> Signup and view all the answers

Which of the following describes intracellular parasites?

<p>Parasites that reside within the cells of the host (A)</p> Signup and view all the answers

What method involves the complete elimination of all living cells, including viruses and spores?

<p>Sterilization (D)</p> Signup and view all the answers

Which method reduces but does not eliminate all microorganisms on a surface?

<p>Disinfection (C)</p> Signup and view all the answers

What is the primary characteristic of osmosis?

<p>Diffusion of water through a selectively permeable membrane (D)</p> Signup and view all the answers

Which of the following best describes obligate parasites?

<p>Parasites that grow only inside living hosts (D)</p> Signup and view all the answers

What is the role of the 'pioneer' colonizer in biofilm formation?

<p>To initiate the attachment of other microbes to a surface (C)</p> Signup and view all the answers

Which of the following does NOT typically describe antibiosis?

<p>Destruction of all microbial life (B)</p> Signup and view all the answers

Which nutrient is a vital component of cytochrome proteins involved in cellular respiration?

<p>Iron (C)</p> Signup and view all the answers

Which treatment aims to reduce microbial populations to public health standards?

<p>Sanitation (D)</p> Signup and view all the answers

What is the primary distinction of active transport compared to passive transport?

<p>Active transport uses ATP to move substances against their concentration gradient. (D)</p> Signup and view all the answers

Which type of symbiotic relationship is characterized by one organism benefiting while the other is neither helped nor harmed?

<p>Commensalism (B)</p> Signup and view all the answers

In what way do monosaccharides and amino acids relate to transport mechanisms across membranes?

<p>They are examples of substances transported actively. (A)</p> Signup and view all the answers

Which statement best describes the characteristic of mutualism?

<p>It is beneficial for both participants and may be obligatory. (A)</p> Signup and view all the answers

How would you define parasitism in the context of symbiotic relationships?

<p>The parasite generally benefits while harming the host. (B)</p> Signup and view all the answers

What does the term 'synergism' refer to in biological interactions?

<p>An interrelationship beneficial to both but not necessary for survival. (D)</p> Signup and view all the answers

Which of the following interactions is deemed 'obligatory'?

<p>Mutualism (C)</p> Signup and view all the answers

Which statement correctly contrasts the energy requirements of active and passive transport?

<p>Active transport uses energy, while passive transport uses potential energy of gradients. (C)</p> Signup and view all the answers

What is the primary purpose of using germicides?

<p>To kill pathogenic microbes (C)</p> Signup and view all the answers

Which physical method is NOT effective in controlling microbial growth?

<p>Increasing humidity (D)</p> Signup and view all the answers

What does the Thermal Death Point (TDP) refer to?

<p>The lowest temperature required to kill all microbes in 10 minutes (D)</p> Signup and view all the answers

What is the purpose of decimal reduction time (DRT)?

<p>To calculate the time needed to reduce a microbial population by 90% (C)</p> Signup and view all the answers

In microbial control, which term describes an agent that inhibits bacterial growth without killing them?

<p>Bacteriostatic (D)</p> Signup and view all the answers

Which of the following is a downside of using heat as a method for microbial control?

<p>It may damage heat-sensitive materials (B)</p> Signup and view all the answers

Which method of microbial control involves the removal of microbes from a specific area?

<p>Degerming (A)</p> Signup and view all the answers

What is the main role of antiseptics in microbial control?

<p>To kill microorganisms on living tissue (C)</p> Signup and view all the answers

Which of the following methods is primarily used for food preservation by removing water from microbes?

<p>Desiccation (D)</p> Signup and view all the answers

What is the principle behind the operation of HEPA filters?

<p>Physical removal of particles through pores (A)</p> Signup and view all the answers

Which of the following statements about pasteurization is correct?

<p>It effectively reduces the number of microorganisms in milk. (B)</p> Signup and view all the answers

What temperature and duration is typically required for hot air sterilization to be effective?

<p>160℃ for 1 hour (A)</p> Signup and view all the answers

What is the primary use of freeze-drying (lyophilization) in food processing?

<p>To remove water and extend shelf life (B)</p> Signup and view all the answers

Which of the following methods is NOT effective against spores and viruses?

<p>Desiccation (C)</p> Signup and view all the answers

In what setting would you most likely find the application of HEPA filters?

<p>In surgical masks during operations (B)</p> Signup and view all the answers

Which statement about ionizing radiation is true?

<p>It requires exposure to gamma rays and electron beams to destroy DNA. (B)</p> Signup and view all the answers

Flashcards

Essential Nutrient

A substance that a microbe absolutely needs for growth and cannot make itself.

Inorganic Nutrient

Atoms or simple molecules containing atoms other than carbon, found in the earth's crust, water, and the atmosphere.

Organic Nutrient

Molecules containing carbon and hydrogen, produced by living organisms.

What is a nutrient?

Any nutrient that must be provided to an organism to sustain its life.

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Microbial Nutrition

The study of how microorganisms obtain and utilize nutrients for their growth and survival.

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Chemoheterotrophs

Organisms that obtain both carbon and energy from organic compounds.

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Parasites

Organisms that obtain nutrients from living hosts, causing damage to tissues or death.

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Ectoparasites

Parasites that live on the body of a host.

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Endoparasites

Parasites that live inside the organs or tissues of a host.

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Intracellular parasites

Parasites that live within cells of a host.

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Obligate parasites

Parasites that cannot survive outside of a living host.

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Osmosis

The movement of water through a semi-permeable membrane from an area of higher water concentration to an area of lower water concentration.

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Selectively Permeable Membrane

A membrane that allows some molecules to pass through but blocks others.

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Active Transport

The movement of molecules across a cell membrane that requires energy from the cell.

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Passive Transport

The movement of molecules across a cell membrane without the cell expending energy.

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Symbiosis

A close and often long-term interaction between two different species.

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Mutualism

A type of symbiosis where both organisms benefit from the relationship and are dependent on each other.

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Commensalism

A type of symbiosis where one organism benefits from the relationship while the other is neither harmed nor benefited.

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Synergism

A type of interaction where two organisms work together, benefiting both, but the relationship is not essential for survival.

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Substances Transported Actively

Examples of substances that are actively transported across cell membranes include:

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Antagonism

A relationship between free-living species where one organism benefits while the other is harmed.

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Antibiosis

A type of antagonism where one organism produces substances that inhibit or kill another organism.

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Biofilm

A community of microbes attached to a surface and to each other.

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Quorum sensing

A chemical communication system used by bacteria to interact with each other.

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Sterilization

The process of killing or removing all living cells, including viruses and spores.

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Disinfection

A process that reduces the total number of microbes on a surface.

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Sanitation

A process that reduces the microbial population to levels considered safe by public health standards.

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Biofilm structure

A community comprised of many microbes with different characteristics which can create varying conditions like pH and oxygen levels.

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Microbial Control

Method that controls microbial growth by killing or inhibiting their growth.

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Antimicrobial Agent

An agent (chemical or physical) that kills microorganisms or inhibits their growth.

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Antiseptic

A mild disinfectant used on skin surfaces to reduce microorganisms.

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Germicide

An agent that kills microbes, like bactericide (kills bacteria), fungicide (kills fungi), or virucide (kills viruses).

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Bacteriostatic

An agent that inhibits microbial growth but doesn't necessarily kill them. Like putting a microbe in a 'time-out' to stop it from multiplying.

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Degerming

The removal of microbes from a limited area, such as a surgical site. It doesn't necessarily kill them, but removes them from the surface.

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Thermal Death Point (TDP)

The lowest temperature that kills all bacteria in a sample within 10 minutes.

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Decimal Reduction Time (DRT)

Time needed to reduce 90% of a bacterial population at a specific temperature. It measures the heat resistance of a microbe.

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Pasteurization

A technique that reduces the number of microorganisms in milk by heating it to a specific temperature for a set time. Common for pasteurizing milk and reducing bacteria.

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Dry Heat Sterilization

A method of sterilization that uses dry heat at high temperatures to kill all microorganisms, including endospores. It is effective for materials that can withstand high temperatures.

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HEPA Filter

A type of filtration used to remove microorganisms from the air. It is commonly used in hospitals, pharmaceutical manufacturing facilities, and operating rooms.

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Filtration

A method of sterilization where a liquid or gas is passed through a filter with pores small enough to trap microorganisms. This is a common way to sterilize liquids and remove particles from the air.

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Desiccation

A method of sterilization that uses the removal of water from microorganisms to inhibit their growth. This is commonly used for food preservation and the inactivation of medications.

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Radiation

A method of sterilization that uses radiation to kill microorganisms. Ionizing radiation is more effective than non-ionizing radiation and can penetrate materials.

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Ionizing Radiation

A type of radiation sterilization that uses gamma rays or high-energy electron beams to damage DNA and kill microorganisms. This method is effective for sterilizing medical supplies, pharmaceuticals, and food.

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Study Notes

Microbial Nutrition

  • Essential nutrient: A substance an organism must receive.
  • Macronutrients: Needed in large quantities for cell structure and metabolism (carbon, hydrogen, oxygen).
  • Micronutrients (trace elements): Needed in smaller amounts for enzyme function and protein structure (e.g., manganese, zinc, nickel).
  • Inorganic nutrients: Atoms or molecules without carbon (found in Earth's crust, water, atmosphere).
  • Organic nutrients: Contain carbon and hydrogen atoms, products of living things (simple organic molecules like methane, large polymers like carbohydrates, lipids, proteins, nucleic acids).

Chemical Analysis of the Microbial Cytoplasm

  • Water: 70% of all cell components.
  • Proteins: 97% of dry cell weight.
  • Organic compounds: 97% of dry cell weight.
  • Elements (CHONPS): 96% of dry cell weight.
  • Few nutrient types synthesize over 5,000 compounds.

What Microbes Eat

  • Heterotrophs: Obtain their carbon from organic substances.
  • Autotrophs: Use inorganic CO₂ as their carbon source. Not nutritionally dependent on other living organisms.
  • Phototrophs: Obtain energy from sunlight.
  • Chemotrophs: Obtain energy from chemical compounds.
  • Chemoheterotrophs: Obtain energy and carbon from organic compounds.
  • Saprobes: Free-living organisms that feed on organic detritus from dead organisms. Recyclers of inorganic nutrients.
  • Parasites: Obtain nutrients from the cells or tissues of a living host and often cause harm.

Autotrophs and their Energy Sources

  • Photoautotrophs: Photosynthesize, using CO₂. (algae, plants, cyanobacteria).
  • Chemoautotrophs: Use inorganic compounds as an energy source, and CO₂ as the carbon source. (methanogens, deep-sea vent bacteria).

Microbial Interactions

  • Microbes usually live in shared habitats.
  • Interactions can be beneficial, harmful, or neutral.
  • Obligatory or non-obligatory to the members.
  • Nutritional interactions are common.

Strong Partnerships: Symbioses

  • Symbiosis: A close partnership between organisms.
  • Mutualism: Both organisms benefit.
  • Commensalism: One organism benefits, the other is unaffected.
  • Parasitism: One organism benefits, the other is harmed.

Associations But Not Partnerships

  • Synergism: Two or more organisms benefit, though no one is completely dependent on another. Beneficial interaction without dependence.
  • Antagonism: One species competes, sometimes inhibiting growth of the other, sometimes producing harmful compounds.
  • Biofilms: Mixed communities attached to surfaces that often work together in complex interactions.

How Microbes Eat: Transport Mechanisms

  • Transport mechanisms: Drive nutrients across cell membranes.
  • Diffusion: Movement of molecules from high to low concentration.
  • Active transport: Movement of molecules from low to high concentration, requiring energy (e.g., ATP).

Methods to control microbial growth

  • Sterilization: Completely eliminates all forms of life.
  • Disinfection: Eliminates most microorganisms but not necessarily all.
  • Sanitation: Reduces microbial levels to safe, public health levels.
  • Physical methods: Heat, desiccation, osmotic pressure, filtration, radiation.
  • Chemical methods: Phenols, halogens, alcohols, heavy metals, surface-active agents, organic acids, aldehydes, antimicrobials.

Additional Physical Methods of Microbial Growth Control

  • Heat: High temperatures denature enzymes, kill microorganisms. (Thermal Death Point (TDP), Thermal Death Time (TDT), Decimal Reduction Time (DRT)).
  • Desiccation: Removal of water inhibits growth
  • Osmotic Pressure: High salt or sugar concentrations cause water loss from cells.
  • Filtration: Removal of microbes by physical barriers with small pores.
  • Radiation: Damaging DNA and other biological structures. (Ionizing, Non-ionizing).

Additional Chemical Methods of Control

  • Phenols and phenolics: Damage cell components.
  • Halogens (iodine, chlorine): Often alter enzymes or disrupt cellular functions .
  • Alcohols: Denature proteins and dissolve lipids, evaporates quickly.
  • Heavy Metals: Denature proteins, prevent microbial growth.
  • Surface-active agents: (soaps, detergents) disrupt cell membranes.
  • Organic acids: Inhibit the growth of certain microorganisms.
  • Aldehydes: Inactivate proteins, used for sterilizing instruments.
  • Antibiotics: Kill or inhibit growth of microbes.

Methods of Microbial Control: Autoclaving, Pasteurization, Low Temperatures

  • Autoclaving: A method of sterilization. Uses steam under pressure. Eliminates all microorganisms.
  • Pasteurization: Reduces microbial load, usually for food. Does not completely sterilize. (e.g., milk pasteurization, beer preservation).
  • Low Temperatures: Slows microbial growth, does not necessarily kill them, often used for food preservation.

Methods of Microbial Control: Drying, Filtration, and Radiation

  • Desiccation (drying): Removes moisture and inhibits growth.
  • Filtration: Removes microbes through a filter which is physically blocking them, usually used to sterilize solutions that cannot be heated.
  • Radiation: Damages DNA or proteins, often used to sterilize or disinfect. Two main types are ionizing and non-ionizing radiation.

Microbial Control: Types, Techniques, and Application

  • Dry heat sterilization: Inactivates heat-resistant microbes using high temperatures, usually with air, and can sterilize objects that cannot be exposed to steam.
  • Direct flaming: Sterilizes loops in microbiological work in a very precise way.
  • HEPA filters: Removes microbes and other small particles from an air supply.
  • Osmotic pressure: High salt or sugar concentrations cause water loss from cells (preserves food).

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