Microbiology Trivia Quiz On Microorganisms!

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Microbiology Trivia Quiz On Microorganisms! - Quiz

As we continue to cover every topic that is set out for us in the syllabus through quizzes that cover each chapter, we are now at chapter seven. In this chapter, we covered a lot on bacterial and archaeal cells. How much do you recall about the chapter? Take up the quiz below and get to find out. Good luck!


Questions and Answers
  • 1. 

    Most bacterial and archaeal cells divide by  

    • A.

      Mitosis

    • B.

      Meiosis

    • C.

      Binary fission

    • D.

      All of the above

    Correct Answer
    C. Binary fission
    Explanation
    Most bacterial and archaeal cells divide by binary fission. This is a form of asexual reproduction in which a single cell divides into two identical daughter cells. During binary fission, the cell's DNA replicates, and the two copies move to opposite ends of the cell. The cell then elongates and eventually divides into two separate cells. This process allows for rapid cell division and population growth in bacteria and archaea. Mitosis and meiosis, on the other hand, are processes of cell division in eukaryotic cells and are not applicable to bacterial and archaeal cells.

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  • 2. 

    All bacterial and archaeal cells are diploid.  

    • A.

      True

    • B.

      False

    Correct Answer
    B. False
    Explanation
    The statement that all bacterial and archaeal cells are diploid is false. Diploidy refers to having two copies of each chromosome, which is not the case for all bacterial and archaeal cells. Bacteria and archaea can have different types of genome organization, such as being haploid (having one copy of each chromosome) or polyploid (having multiple copies of each chromosome). Therefore, not all bacterial and archaeal cells are diploid.

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  • 3. 

    Which of the following is the correct order for binary fission?  

    • A.

      A septum forms at midcell, the cell elongates, replicates its chromosome, and separates the chromosome into the two parts of the cell

    • B.

      The cell elongates, a septum forms at midcell, the cell replicates its chromosome, and separates the chromosome into the two parts of the cell

    • C.

      The cell elongates, replicates its chromosome, and separates the chromosome into the two parts of the cell, and a septum forms at midcell

    • D.

      None of the above

    Correct Answer
    C. The cell elongates, replicates its chromosome, and separates the chromosome into the two parts of the cell, and a septum forms at midcell
    Explanation
    In binary fission, the correct order of events is that the cell elongates, replicates its chromosome, separates the chromosome into the two parts of the cell, and finally, a septum forms at midcell. This ensures that each daughter cell receives a copy of the replicated chromosome before the cell divides completely.

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  • 4. 

    The __________ is a group of proteins needed for DNA synthesis that assembles at the origin of replication.  

    • A.

      Septum

    • B.

      Replisome

    • C.

      Prospore

    • D.

      None of the above

    Correct Answer
    B. Replisome
    Explanation
    The replisome is a group of proteins needed for DNA synthesis that assembles at the origin of replication. It is responsible for unwinding the DNA double helix, synthesizing new DNA strands, and proofreading and repairing any errors. The replisome ensures accurate and efficient replication of the DNA during cell division.

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  • 5. 

    The process of forming a cross wall between two daughter cells is known as  

    • A.

      Replication

    • B.

      Septation

    • C.

      Sporulation

    • D.

      Mitosis

    Correct Answer
    B. Septation
    Explanation
    Septation is the process of forming a cross wall between two daughter cells. This occurs during cell division, specifically in bacteria and fungi. The cross wall, or septum, separates the two daughter cells and allows them to function as independent entities. Replication refers to the process of duplicating DNA, sporulation is the formation of spores, and mitosis is a type of cell division in eukaryotic cells.

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  • 6. 

    The cell wall of bacteria constrains the ___________ _________ that results from the osmolarity of the cytoplasmic contents.  

    Correct Answer
    turgor pressure
    Explanation
    The cell wall of bacteria provides structural support and prevents the cell from bursting due to the osmotic pressure created by the cytoplasmic contents. This pressure, known as turgor pressure, is exerted on the cell wall and helps maintain the shape and integrity of the bacterial cell.

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  • 7. 

    The site at which replication of DNA starts in bacterial cells is known as the __________ of ___________. (answer, answer)  

    Correct Answer
    origin, replication
    Explanation
    In bacterial cells, the site where replication of DNA begins is called the origin. This is where the replication process starts and DNA strands are unwound and separated. Replication refers to the process of copying DNA to produce two identical DNA molecules.

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  • 8. 

    The purpose of the penicillin binding proteins is to link phospholipids together in the cellular membrane.  

    • A.

      True

    • B.

      False

    Correct Answer
    B. False
    Explanation
    Penicillin binding proteins (PBPs) are enzymes involved in the synthesis of peptidoglycan, a major component of bacterial cell walls. They catalyze the cross-linking of peptide chains in the peptidoglycan layer, providing structural integrity to the cell wall. PBPs do not have a role in linking phospholipids together in the cellular membrane. Therefore, the given statement is false.

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  • 9. 

    The actin-like protein that seems to be involved in determining cell shape is  

    • A.

      MreB

    • B.

      ActA

    • C.

      SpnC

    • D.

      FtsZ

    Correct Answer
    A. MreB
    Explanation
    MreB is the correct answer because it is an actin-like protein that plays a key role in determining cell shape. It forms a helical structure underneath the cell membrane and helps in guiding the synthesis of new cell wall material. MreB is involved in maintaining the rod-like shape of bacterial cells and is essential for their proper growth and division.

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  • 10. 

    During cytokinesis, a critical step in septation is the assembly of the  

    • A.

      Replisome

    • B.

      Spindle body

    • C.

      Z ring

    • D.

      Cytoskeletal spiral

    Correct Answer
    C. Z ring
    Explanation
    During cytokinesis, the Z ring plays a critical role in septation. The Z ring is a structure made up of proteins that forms a contractile ring at the site of cell division. It functions by constricting and pinching off the cell membrane, leading to the separation of the two daughter cells. The assembly of the Z ring is essential for the successful completion of cytokinesis and the formation of two separate cells. The other options, replisome, spindle body, and cytoskeletal spiral, are not directly involved in septation during cytokinesis.

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  • 11. 

    The limitation on microbial growth rate at high nutrient levels is  

    • A.

      The rate of protein synthesis

    • B.

      The rate of DNA replication

    • C.

      The saturation of the transport proteins for nutrient uptake.

    • D.

      All of the choices

    Correct Answer
    C. The saturation of the transport proteins for nutrient uptake.
    Explanation
    At high nutrient levels, the limitation on microbial growth rate is the saturation of the transport proteins for nutrient uptake. This means that even though there is an abundance of nutrients available, the transport proteins responsible for bringing these nutrients into the microbial cells become saturated and cannot take in any more. As a result, the growth rate of the microbes is limited because they are unable to uptake and utilize the excess nutrients efficiently. This is why the saturation of transport proteins for nutrient uptake is the correct answer.

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  • 12. 

    The total number of viable microorganisms remains constant in stationary phase because  

    • A.

      There is a balance between cell division and cell death.

    • B.

      There is a cessation of cell division even though the cells may remain metabolically active.

    • C.

      Either there is a balance between cell division and cell death or there is a cessation of cell division even though the cells may remain metabolically active.

    • D.

      None of the choices

    Correct Answer
    C. Either there is a balance between cell division and cell death or there is a cessation of cell division even though the cells may remain metabolically active.
    Explanation
    In the stationary phase, the total number of viable microorganisms remains constant because there is either a balance between cell division and cell death or a cessation of cell division even though the cells may remain metabolically active. This means that while some cells may continue to divide and produce new cells, an equal number of cells may die, resulting in a constant population size. Alternatively, cell division may stop altogether, but the remaining cells can still carry out metabolic activities, which helps maintain the overall population.

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  • 13. 

    Cells may enter stationary phase because of  

    • A.

      The depletion of an essential nutrient

    • B.

      A lack of available oxygen

    • C.

      The accumulation of toxic waste products

    • D.

      All of the choices

    Correct Answer
    D. All of the choices
    Explanation
    Cells may enter stationary phase because of the depletion of an essential nutrient, a lack of available oxygen, or the accumulation of toxic waste products. This means that any one of these factors can cause cells to stop growing and enter a state of dormancy.

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  • 14. 

    A culture in a closed vessel to which no additional medium is added and from which no waste products are removed is called a __________ culture.  

    • A.

      Continuous

    • B.

      Batch

    • C.

      Fed-batch

    • D.

      Semicontinuous

    Correct Answer
    B. Batch
    Explanation
    A culture in a closed vessel to which no additional medium is added and from which no waste products are removed is called a batch culture. In a batch culture, all the necessary nutrients are added at the beginning and the culture is allowed to grow without any further interventions. This type of culture is commonly used in laboratory settings for studying the growth and behavior of microorganisms.

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  • 15. 

    Given a log phase bacterial culture with 1 x 10^6 cells per ml and a generation time of 30 minutes, how long does it take the culture to reach a density of 6.4 x 10^7 cells per ml?    

    • A.

      1 hour

    • B.

      2 hours

    • C.

      3 hours

    • D.

      4 hours

    Correct Answer
    C. 3 hours
    Explanation
    The generation time of 30 minutes means that the number of cells in the bacterial culture doubles every 30 minutes. Starting with 1 x 10^6 cells per ml, it would take 30 minutes for the culture to reach 2 x 10^6 cells per ml, another 30 minutes to reach 4 x 10^6 cells per ml, and so on. To reach a density of 6.4 x 10^7 cells per ml, it would take a total of 3 hours, as the number of cells doubles six times (2^6 = 64) within that time frame. Therefore, the correct answer is 3 hours.

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  • 16. 

    Microorganisms are most nearly uniform in terms of chemical and physiological properties during __________ phase.  

    • A.

      Lag

    • B.

      Exponential

    • C.

      Stationary

    • D.

      Decline

    Correct Answer
    B. Exponential
    Explanation
    During the exponential phase, microorganisms are actively dividing and multiplying at a rapid rate. This phase is characterized by a constant and exponential increase in the number of microorganisms. As a result, the chemical and physiological properties of the microorganisms are most nearly uniform during this phase because they are all undergoing similar growth and metabolic processes.

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  • 17. 

    Which of the following is a reason for the occurrence of a lag phase in a bacterial growth curve?  

    • A.

      The cells may be old and depleted of ATP, essential cofactors, and ribosomes that must be synthesized before growth can begin.

    • B.

      The medium may be different from the previous growth medium so that the cells must synthesize new enzymes to use different nutrients.

    • C.

      The organisms may have been injured and require time to recover.

    • D.

      All of these are potential reasons.

    Correct Answer
    D. All of these are potential reasons.
    Explanation
    The occurrence of a lag phase in a bacterial growth curve can be attributed to multiple reasons. The cells may be old and depleted of essential components like ATP, cofactors, and ribosomes that are necessary for growth initiation. Additionally, if the medium used for growth is different from the previous one, the cells may need to synthesize new enzymes to utilize different nutrients, leading to a lag phase. Furthermore, if the organisms have been injured, they may require time to recover before they can resume growth. Therefore, all of the given options are potential reasons for the occurrence of a lag phase.

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  • 18. 

    When a young, vigorously growing culture of bacteria is transferred to fresh medium of the same composition, the lag phase is usually short or absent.  

    • A.

      True

    • B.

      False

    Correct Answer
    A. True
    Explanation
    When a young, vigorously growing culture of bacteria is transferred to fresh medium of the same composition, the lag phase is usually short or absent. This is because the bacteria are already adapted to the conditions of the medium and can immediately resume their growth without any delay or adjustment period. The absence of a lag phase indicates that the bacteria can quickly start utilizing the available nutrients and resources in the fresh medium, leading to rapid growth. Therefore, the statement "True" is correct.

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  • 19. 

    During the lag phase of microbial growth, the cells are metabolically inactive.  

    • A.

      True

    • B.

      False

    Correct Answer
    B. False
    Explanation
    During the lag phase of microbial growth, the cells are actually metabolically active. Although there may not be a significant increase in cell number, the cells are actively preparing for growth by synthesizing enzymes and other necessary molecules. This phase is characterized by a period of adaptation to the new environment before the cells enter the exponential growth phase. Therefore, the given statement is false.

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  • 20. 

    The length of the lag phase of growth can vary depending on  

    • A.

      The condition of the microorganisms

    • B.

      The nature of the growth medium

    • C.

      The temperature

    • D.

      All of the choices

    Correct Answer
    D. All of the choices
    Explanation
    The length of the lag phase of growth can vary depending on the condition of the microorganisms, the nature of the growth medium, and the temperature. This means that all of these factors can influence the duration of the lag phase. The condition of the microorganisms refers to their health and vitality, which can affect their ability to start growing. The nature of the growth medium, such as its nutrient composition, can also impact the lag phase. Additionally, temperature can play a role, as different microorganisms have different optimal growth temperatures. Therefore, all of these choices can contribute to the length of the lag phase.

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  • 21. 

    When a young, vigorously growing culture of bacteria is transferred to fresh medium of different composition, the lag phase is usually short or absent.  

    • A.

      True

    • B.

      False

    Correct Answer
    B. False
    Explanation
    When a young, vigorously growing culture of bacteria is transferred to fresh medium of different composition, the lag phase is usually long or present. This is because the bacteria need time to adjust to the new environment and activate the necessary genes and enzymes to utilize the nutrients in the fresh medium. This adjustment period is known as the lag phase.

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  • 22. 

    The growth rate of a given species of microorganism is dependent on the composition of the medium in which it is grown.  

    • A.

      True

    • B.

      False

    Correct Answer
    A. True
    Explanation
    The growth rate of a species of microorganism is influenced by the composition of the medium in which it is grown. This means that the nutrients, pH level, temperature, and other factors present in the medium can either promote or inhibit the growth of the microorganism. Therefore, it is true that the growth rate of a microorganism is dependent on the composition of the medium.

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  • 23. 

    Microbial __________ is an increase in cell constituents that may or may not be accompanied by an increase in cell number.  

    Correct Answer
    growth
    Explanation
    Microbial growth refers to an increase in cell constituents, such as proteins, nucleic acids, and lipids, within a microorganism. This increase in cell constituents can occur with or without an increase in cell number. It is an essential process for microorganisms to reproduce and multiply.

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  • 24. 

    The __________ __________ is the length of time it takes for a population of microorganisms to double in number. (2 words)  

    Correct Answer
    generation time
    Explanation
    The generation time refers to the time it takes for a population of microorganisms to double in number. It is a measure of the growth rate of the population and is influenced by various factors such as nutrient availability, temperature, and other environmental conditions. Understanding the generation time is important in fields such as microbiology and epidemiology, as it helps in predicting and controlling the growth of microorganisms.

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  • 25. 

    If all cell components are synthesized at constant rates relative to one another, the culture is said to be in __________ growth; however, if the rates of synthesis of some components change relative to the rates of synthesis of other components, the culture is said to be in __________ growth. (answer, answer)  

    Correct Answer
    balanced, unbalanced
    Explanation
    In a balanced growth culture, all cell components are synthesized at constant rates relative to one another. This means that the rates of synthesis of different components are proportional and in balance with each other. On the other hand, in an unbalanced growth culture, the rates of synthesis of some components change relative to the rates of synthesis of other components. This indicates an imbalance in the rates of synthesis, where some components are being synthesized at different rates compared to others.

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  • 26. 

    Growth is said to be __________ when all cellular components are synthesized at constant rates relative to one another.  

    Correct Answer
    balanced
    Explanation
    In growth, when all cellular components are synthesized at constant rates relative to one another, it is referred to as "balanced" growth. This means that the synthesis of proteins, nucleic acids, lipids, and other cellular components is coordinated and occurs at equal rates, ensuring that the cell maintains a consistent and proportional growth.

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  • 27. 

    At 4:00 p.m. a closed flask of sterile broth is inoculated with 10,000 cells. The lag phase lasts 1 hour. At 9:00 p.m. the culture enters stationary phase with a population of 65 million cells. At what time is the population half maximal?  

    • A.

      6:30

    • B.

      7:20

    • C.

      8:20

    • D.

      8:40

    Correct Answer
    D. 8:40
  • 28. 

    At 4:00 p.m. a closed flask of sterile broth is inoculated with 10,000 cells. The lag phase lasts 1 hour. At 9:00 p.m. the log phase culture has population of 65 million cells. The approximate number of generations that has occurred is  

    • A.

      5

    • B.

      13

    • C.

      21

    • D.

      27

    Correct Answer
    B. 13
    Explanation
    The log phase is the phase of bacterial growth where the population doubles at a constant rate. Since the population at 9:00 p.m. is 65 million cells and the initial population at 4:00 p.m. is 10,000 cells, we can calculate the number of generations by dividing the final population by the initial population.
    65 million cells / 10,000 cells = 6,500 generations
    However, we need to consider that the lag phase lasts for 1 hour, so we subtract 1 from the total number of generations.
    6,500 generations - 1 = 6,499 generations.
    Since the options given are all integers, the approximate number of generations is 13.

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  • 29. 

    Which of the following can be used to estimate the number of microorganisms in a culture?  

    • A.

      Direct counts of microbial cells

    • B.

      Counts of viable cells using colony growth procedures

    • C.

      Measurements of microbial biomass

    • D.

      All of the choices

    Correct Answer
    D. All of the choices
    Explanation
    All of the choices can be used to estimate the number of microorganisms in a culture. Direct counts of microbial cells involve physically counting the individual cells under a microscope. Counts of viable cells using colony growth procedures involve counting the number of visible colonies that grow on agar plates, which represent viable cells. Measurements of microbial biomass involve quantifying the total mass or weight of the microorganisms in the culture.

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  • 30. 

    Which of these methods can be used to determine the number of viable microorganisms in a sample?  

    • A.

      Light scattering in a spectrophotometer

    • B.

      Measuring total cell mass

    • C.

      Measuring colony forming units per ml

    • D.

      Counting a known volume of cells in a hemocytometer

    Correct Answer
    C. Measuring colony forming units per ml
    Explanation
    Measuring colony forming units per ml is a method commonly used to determine the number of viable microorganisms in a sample. This method involves diluting the sample and then plating it on a solid growth medium. Each viable microorganism will form a visible colony on the plate, and by counting the number of colonies, the concentration of viable microorganisms in the original sample can be calculated. This method is widely used in microbiology to assess the viability and growth of microorganisms.

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  • 31. 

    At 4:00 p.m. a closed flask of sterile broth is inoculated with 10,000 cells. The lag phase lasts 1 hour. At 9:00 p.m. the log phase culture has a population of 65 million cells. The mean generation time is approximately  

    • A.

      10 minutes

    • B.

      20 minutes

    • C.

      30 minutes

    • D.

      40 minutes

    Correct Answer
    B. 20 minutes
    Explanation
    The mean generation time can be calculated by dividing the total time taken for the population to double by the number of generations. In this case, the population goes from 10,000 cells to 65 million cells, which is an increase of 6,500 times. Since the log phase culture lasts for 5 hours (from 4:00 p.m. to 9:00 p.m.), and each generation time is the same, the total time taken for the population to double is 5 hours divided by the number of generations. Therefore, the mean generation time is approximately 5 hours divided by 6,500, which is approximately 46 seconds. Since 1 hour is equal to 60 minutes, the mean generation time is approximately 46 seconds multiplied by 60, which is approximately 27.6 minutes. Therefore, the correct answer is 20 minutes.

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  • 32. 

    A culture system with constant environmental conditions maintained through continual provision of nutrient and removal of wastes is called __________ culture system.  

    • A.

      Continuous

    • B.

      Batch

    • C.

      Fed-batch

    • D.

      Semicontinuous

    Correct Answer
    A. Continuous
    Explanation
    A culture system with constant environmental conditions maintained through continual provision of nutrient and removal of wastes is called a continuous culture system. In this system, fresh nutrient is continuously added to the culture while waste products are continuously removed, allowing for a steady state of growth and maintenance of the culture. This differs from batch culture, fed-batch culture, and semicontinuous culture systems where the nutrient and waste removal processes are not continuous.

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  • 33. 

    An open system in which the growth rate is maintained by adding a nutrient (present in limiting quantities) at the same rate that medium containing microorganisms is removed is called  

    • A.

      Manostat

    • B.

      Chemostat

    • C.

      Turbidostat

    • D.

      Culturostat

    Correct Answer
    B. Chemostat
    Explanation
    A chemostat is an open system in which the growth rate of microorganisms is maintained by adding a nutrient at the same rate that the medium containing the microorganisms is removed. This ensures that the nutrient remains in limiting quantities and allows for continuous growth of the microorganisms. The other options, manostat, turbidostat, and culturostat, do not specifically refer to systems that maintain growth rate by adding and removing nutrients in this way.

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  • 34. 

    An open system in which the growth rate is maintained by the removal and addition of media at such a rate as to maintain a constant cell density is called a  

    • A.

      Manostat

    • B.

      Chemostat

    • C.

      Turbidostat

    • D.

      Culturostat

    Correct Answer
    C. Turbidostat
    Explanation
    An open system in which the growth rate is maintained by the removal and addition of media at such a rate as to maintain a constant cell density is called a turbidostat. In a turbidostat, the cell density is monitored by measuring the turbidity of the culture, and the media flow rate is adjusted accordingly to maintain a constant turbidity or cell density. This allows for continuous growth of the culture without reaching a stationary phase.

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  • 35. 

    One of the major advantages of a continuous culture system is that the cells can be maintained in the exponential growth phase for extended periods of time.  

    • A.

      True

    • B.

      False

    Correct Answer
    A. True
    Explanation
    A continuous culture system allows for the continuous supply of nutrients and removal of waste, which promotes the constant growth of cells. This system ensures that the cells are always in the exponential growth phase, where they are dividing rapidly and at their highest metabolic activity. By maintaining cells in this phase for extended periods of time, it allows for a higher yield of biomass or desired products to be produced.

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  • 36. 

    In a continuous culture system, the rate at which media is added and removed is called the __________ rate.  

    • A.

      Dilution

    • B.

      Chemostatic

    • C.

      Pass-through

    • D.

      Flow-through

    Correct Answer
    A. Dilution
    Explanation
    In a continuous culture system, the rate at which media is added and removed is called the dilution rate. This rate is important as it determines the growth rate of the culture and helps maintain a steady-state condition by diluting out the waste products and providing fresh nutrients. By adjusting the dilution rate, the concentration of cells can be controlled, allowing for optimal growth conditions. The dilution rate is a key parameter in continuous culture systems and plays a crucial role in maintaining a stable and controlled environment for the culture.

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  • 37. 

    Which of the following is considered a cardinal growth temperature?  

    • A.

      The minimum temperature

    • B.

      The maximum temperature

    • C.

      The optimum temperature

    • D.

      All of these are considered cardinal growth temperatures

    Correct Answer
    D. All of these are considered cardinal growth temperatures
    Explanation
    The correct answer is "All of these are considered cardinal growth temperatures." Cardinal growth temperatures refer to the minimum, maximum, and optimum temperatures at which an organism can grow. These temperatures are crucial for determining the range of conditions in which an organism can thrive and reproduce. By considering all three cardinal temperatures, scientists can better understand the environmental conditions that support the growth and survival of different organisms.

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  • 38. 

    Organisms that grow well at 0C and have optimum growth temperatures of 15C or lower are called  

    • A.

      Psychrothrophs

    • B.

      Psychrophiles

    • C.

      Frigiphiles

    • D.

      Mesophiles

    Correct Answer
    B. Psychrophiles
    Explanation
    Psychrophiles are organisms that can grow well at 0C and have an optimum growth temperature of 15C or lower. They are adapted to cold environments and thrive in temperatures that would be considered too cold for most other organisms. These organisms have specialized enzymes and cellular structures that allow them to function and reproduce in low temperatures.

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  • 39. 

    Organisms that grow at 0C and have a maximum growth temperature of 35C are called  

    • A.

      Psychrotrophs

    • B.

      Psychrophiles

    • C.

      Frigiphiles

    • D.

      Mesophiles

    Correct Answer
    A. Psychrotrophs
    Explanation
    Psychrotrophs are organisms that can grow at low temperatures, such as 0°C, but also have a maximum growth temperature of 35°C. This means that they are able to survive and reproduce in cold environments, but they can also tolerate and grow at slightly higher temperatures. Psychrophiles, on the other hand, are organisms that specifically thrive in cold temperatures and have a maximum growth temperature below 20°C. Frigiphiles and mesophiles are not relevant to this question.

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  • 40. 

    Organisms that do not require oxygen for growth but grow better in its presence are called  

    • A.

      Facultative anaerobes

    • B.

      Microaerophiles

    • C.

      Aerotolerant

    • D.

      Anoxygenic

    Correct Answer
    A. Facultative anaerobes
    Explanation
    Facultative anaerobes are organisms that can survive and grow in both the presence and absence of oxygen. While they can utilize oxygen for growth, they are also capable of switching to anaerobic metabolism in the absence of oxygen. This flexibility allows them to adapt to different environmental conditions and utilize different energy sources. Therefore, facultative anaerobes can grow better in the presence of oxygen, but they are not dependent on it for survival.

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  • 41. 

    Organisms that ignore oxygen and grow equally well in its presence or absence are called  

    • A.

      Facultative anaerobes

    • B.

      Microaerophiles

    • C.

      Aerotolerant

    • D.

      Anoxygenic

    Correct Answer
    C. Aerotolerant
    Explanation
    Aerotolerant organisms are able to grow equally well in the presence or absence of oxygen. They are not dependent on oxygen for their growth and can survive in environments with or without oxygen. This ability makes them different from obligate aerobes, which require oxygen for growth, and obligate anaerobes, which cannot survive in the presence of oxygen. Facultative anaerobes can also grow in the absence of oxygen, but they prefer to use oxygen if it is available. Microaerophiles require low levels of oxygen to grow, while anoxygenic organisms do not use oxygen for their metabolism at all.

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  • 42. 

    Organisms that are damaged by the normal atmospheric levels of oxygen (20%) but require oxygen at levels of 2–10% for growth are called  

    • A.

      Facultative anaerobes

    • B.

      Microaerophiles

    • C.

      Aerotolerant

    • D.

      Anoxygenic

    Correct Answer
    B. Microaerophiles
    Explanation
    Microaerophiles are organisms that are damaged by the normal atmospheric levels of oxygen (20%) but require oxygen at levels of 2-10% for growth. They are able to survive and grow in environments with lower oxygen levels, but high levels of oxygen are harmful to them. This is why they are called microaerophiles.

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  • 43. 

    When a microorganism is placed in a(n) __________ solution, water will enter into the cell and cause it to burst unless something is done to prevent this.  

    • A.

      Hypotonic

    • B.

      Isotonic

    • C.

      Hypertonic

    • D.

      Osmotonic

    Correct Answer
    A. Hypotonic
    Explanation
    When a microorganism is placed in a hypotonic solution, water will enter into the cell due to osmosis. This is because the concentration of solutes outside the cell is lower than inside the cell. As water enters the cell, it causes an influx of water, leading to an increase in the volume of the cell. If nothing is done to prevent this, the cell will continue to swell and eventually burst.

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  • 44. 

    The membranes of psychrophilic bacteria have relatively high levels of __________ fatty acids, which allow them to remain semi-fluid at cold temperatures.  

    • A.

      Saturated

    • B.

      Unsaturated

    • C.

      Sterol

    • D.

      Aromatic

    Correct Answer
    B. Unsaturated
    Explanation
    The membranes of psychrophilic bacteria have relatively high levels of unsaturated fatty acids. Unsaturated fatty acids have double bonds in their carbon chains, which introduce kinks and prevent the fatty acids from packing closely together. This results in a more fluid and flexible membrane, allowing the bacteria to remain semi-fluid at cold temperatures.

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  • 45. 

    Organisms that are not drastically affected by increased pressure are called  

    • A.

      Barotolerant

    • B.

      Osmotolerant

    • C.

      Barophilic

    • D.

      Osmophilic

    Correct Answer
    A. Barotolerant
    Explanation
    Barotolerant organisms are able to tolerate increased pressure without being drastically affected. This means that they can survive and function relatively normally even in high-pressure environments.

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  • 46. 

    Organisms that require increased pressure for optimum growth are called  

    • A.

      Barotolerant

    • B.

      Osmotolerant

    • C.

      Barophilic

    • D.

      Osmophilic

    Correct Answer
    C. Barophilic
    Explanation
    Barophilic organisms are those that require increased pressure for optimum growth. This means that they thrive in high-pressure environments, such as deep-sea environments where the pressure is much higher than at the surface. These organisms have adapted to withstand and even require these high pressures for their biological processes.

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  • 47. 

    Most microorganisms maintain their internal pH  

    • A.

      Near neutral (pH 7).

    • B.

      Near their optimum growth pH.

    • C.

      Slightly acidic (pH 4–6).

    • D.

      Slightly alkaline (pH 8–10).

    Correct Answer
    A. Near neutral (pH 7).
    Explanation
    Most microorganisms maintain their internal pH near neutral (pH 7) because this is the pH at which most cellular processes occur optimally. Maintaining a neutral internal pH helps to ensure that enzymes and other proteins function properly, allowing the microorganism to carry out essential metabolic activities. Deviations from the optimal pH can disrupt cellular processes and lead to cell damage or death. Therefore, microorganisms have evolved mechanisms to regulate their internal pH and keep it close to neutral.

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  • 48. 

    Organisms that grow near deep-sea volcanic vents are likely to be  

    • A.

      Psychrophilic

    • B.

      Psychrotrophic

    • C.

      Mesophilic

    • D.

      Thermophilic

    Correct Answer
    D. Thermophilic
    Explanation
    Organisms that grow near deep-sea volcanic vents are likely to be thermophilic because these vents release hot water and minerals, creating a high-temperature environment. Thermophilic organisms are adapted to thrive in extreme heat and can withstand temperatures that would be lethal to other organisms. They have specialized enzymes and proteins that are stable at high temperatures, allowing them to carry out their metabolic processes effectively. Therefore, it is reasonable to expect that the organisms near deep-sea volcanic vents would be thermophilic.

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  • 49. 

    Organisms that grow near deep-sea volcanic vents are likely to be  

    • A.

      Alkylophilic

    • B.

      Acidophilic

    • C.

      Barophilic or barotolerant

    • D.

      Picrophilic

    Correct Answer
    C. Barophilic or barotolerant
    Explanation
    Organisms that grow near deep-sea volcanic vents are likely to be barophilic or barotolerant. This is because deep-sea volcanic vents are characterized by high pressure due to the depth of the ocean. Barophilic organisms are able to thrive under high pressure conditions, while barotolerant organisms can tolerate high pressure but may not necessarily require it for growth.

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  • 50. 

    Organisms that grow in the mud under relatively nonturbulent bodies of water are likely to be  

    • A.

      Obligate aerobes

    • B.

      Thermophilic

    • C.

      Barophilic

    • D.

      Anaerobes

    Correct Answer
    D. Anaerobes
    Explanation
    Organisms that grow in the mud under relatively nonturbulent bodies of water are likely to be anaerobes. This is because the mud at the bottom of bodies of water can become oxygen-depleted due to lack of circulation and high levels of organic matter. Anaerobic organisms are adapted to survive in environments with low or no oxygen availability, making them well-suited for these conditions. They can obtain energy through processes such as fermentation or anaerobic respiration, which do not require oxygen.

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Quiz Review Timeline +

Our quizzes are rigorously reviewed, monitored and continuously updated by our expert board to maintain accuracy, relevance, and timeliness.

  • Current Version
  • Mar 20, 2023
    Quiz Edited by
    ProProfs Editorial Team
  • Jun 02, 2012
    Quiz Created by
    Andreazza
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