Microbiology Trivia Quiz For Students!

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  • 1/50 Questions

    Microorganisms that derive nutrients from the cells or tissues of the host are:

    • Parasites
    • Suprobes
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About This Quiz

How do you feel when you hear that you many have an assessment quiz coming up in no time? The quiz below is perfect for ensuring that you do not freeze or be in doubt when the teachers come to you with a surprise quiz. Why don’t you try it out and see how many marks you would get if this was a surprise quiz?

Microbiology Quizzes & Trivia

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  • 2. 

    Autotrophs which derive their energy from sunlight are:

    • Chemoautotrophs

    • Photoautotrophs

    Correct Answer
    A. Photoautotrophs
    Explanation
    Photoautotrophs are organisms that can produce their own food using energy from sunlight. They use a process called photosynthesis to convert sunlight, carbon dioxide, and water into glucose and oxygen. This ability to harness sunlight as an energy source is what distinguishes them from chemoautotrophs, which derive their energy from chemical reactions. Therefore, the correct answer is photoautotrophs.

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  • 3. 

    The term genotype refers to an organism's:

    • Measurable features

    • Genetic makeup

    • Mutation rate

    • Recombination capabilities

    Correct Answer
    A. Genetic makeup
    Explanation
    The term genotype refers to an organism's genetic makeup, which includes the specific combination of genes that an organism possesses. It determines the traits and characteristics of an organism, such as its physical appearance, behavior, and susceptibility to certain diseases. Genotype is inherited from parents and can influence the phenotype, which is the observable or measurable features of an organism. Therefore, the correct answer is "genetic makeup."

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  • 4. 

    Nutrients required in relatively large quantities that play a role in cell structure and function are:

    • Micronutrients

    • Macronutrients

    Correct Answer
    A. Macronutrients
    Explanation
    Macronutrients are the nutrients required in relatively large quantities that play a vital role in cell structure and function. These include carbohydrates, proteins, and fats. Carbohydrates provide energy to cells, proteins are essential for cell growth and repair, and fats serve as a source of energy and help in the absorption of certain vitamins. These macronutrients are necessary for overall health and are needed in larger amounts compared to micronutrients, which are required in smaller quantities.

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  • 5. 

    Microorganisms that can grow only in the absence of oxygen are called:

    • Obligate aerobes

    • Obligate anaerobes

    • Faculative

    • None of these

    Correct Answer
    A. Obligate anaerobes
    Explanation
    Obligate anaerobes are microorganisms that can only grow in the absence of oxygen. They are unable to survive in the presence of oxygen and may even be harmed by it. These organisms have adapted to environments where oxygen is limited or absent, and they obtain their energy through anaerobic respiration or fermentation. Obligate anaerobes are often found in environments such as deep soil layers, sediments, and the digestive tracts of animals. They play important roles in various ecological processes, such as decomposition and nitrogen cycling.

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  • 6. 

    The process of heat applied to liquids to destroy infectious and spoilage agents while retaining the liquids flavor and food value is called ____________.

    • Steam autoclaving

    • Pasteurization

    • Dry heat

    • Boiling

    Correct Answer
    A. Pasteurization
    Explanation
    Pasteurization is the correct answer because it refers to the process of heating liquids, such as milk or juice, to a specific temperature to kill harmful bacteria and other microorganisms while preserving the flavor and nutritional value of the liquid. This process was developed by Louis Pasteur in the 19th century and is commonly used in the food and beverage industry to ensure the safety and quality of products.

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  • 7. 

    Bacteria which may or may not use oxygen are:

    • Aerobic

    • Capnic

    • Facultative

    • Anaerobic

    Correct Answer
    A. Facultative
    Explanation
    Facultative bacteria are able to survive and grow both in the presence and absence of oxygen. They have the ability to switch between aerobic respiration (using oxygen) and anaerobic respiration (not using oxygen) depending on the availability of oxygen in their environment. This flexibility allows facultative bacteria to adapt to different conditions and utilize different metabolic pathways for energy production.

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  • 8. 

    The growth of microbes in blood and other tissues is known as __________.

    • Asepsis

    • Sepsis

    Correct Answer
    A. Sepsis
    Explanation
    Sepsis refers to the growth of microbes in blood and other tissues. It is a potentially life-threatening condition caused by the body's response to an infection. During sepsis, the immune system releases chemicals into the bloodstream to fight the infection, but these chemicals can cause inflammation throughout the body, leading to organ damage and failure. Prompt medical intervention is crucial in treating sepsis to prevent further complications and improve patient outcomes.

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  • 9. 

    Sterilizing medical products such as drugs, vaccines and medical instruments is carried out with _____________ radiation.

    • Ionizing

    • Nonionizing

    Correct Answer
    A. Ionizing
    Explanation
    Sterilizing medical products requires a high level of effectiveness in killing microorganisms. Ionizing radiation, such as gamma rays and X-rays, have high energy levels that can penetrate materials and damage the DNA of microorganisms, effectively killing them. Nonionizing radiation, on the other hand, has lower energy levels and cannot penetrate materials as effectively, making it less suitable for sterilization purposes. Therefore, ionizing radiation is the correct answer for sterilizing medical products.

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  • 10. 

    If the anticodon on transfer RNA is UGA the matching codon on messenger RNA is:

    • AGA

    • ACU

    • UTA

    • UCA

    Correct Answer
    A. ACU
    Explanation
    The anticodon on transfer RNA is the complementary sequence to the codon on messenger RNA. In this case, the anticodon UGA would pair with the codon ACU.

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  • 11. 

    A permanent, heritable alteration in the genetic information of a cell is called:

    • Denaturation

    • Mutation

    • Transfection

    • Phosphorylation

    Correct Answer
    A. Mutation
    Explanation
    A permanent, heritable alteration in the genetic information of a cell is called a mutation. This refers to a change in the DNA sequence, which can occur due to various factors such as exposure to mutagens or errors during DNA replication. Mutations can lead to genetic diversity and can have significant impacts on an organism's traits and functions.

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  • 12. 

    Microbes that must obtain their carbon in organic forms are:

    • Autotrophs

    • Heterotrophs

    Correct Answer
    A. Heterotrophs
    Explanation
    Microbes that must obtain their carbon in organic forms are called heterotrophs. Heterotrophs are unable to synthesize their own organic compounds and instead rely on consuming organic matter produced by other organisms. They obtain energy by breaking down complex organic molecules into simpler ones through processes such as fermentation or respiration. This is in contrast to autotrophs, which can produce their own organic compounds using inorganic sources of carbon, such as carbon dioxide.

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  • 13. 

    In a bacterial growth curve the time during which the growth rate is equal to the death rate is the _________ phase.

    • Lag

    • Log

    • Stationary

    • Death

    Correct Answer
    A. Stationary
    Explanation
    The stationary phase in a bacterial growth curve refers to the period when the growth rate of bacteria is equal to the death rate. During this phase, the number of new cells being produced is balanced by the number of cells dying, resulting in a stable population size. This phase occurs after the lag phase (when bacteria are adjusting to their environment) and before the death phase (when the death rate exceeds the growth rate).

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  • 14. 

    The process of genetic transfer between bacteria which requires cell to cell contact is:

    • Transfection

    • Transformation

    • Conjugation

    • Transposons

    Correct Answer
    A. Conjugation
    Explanation
    Conjugation is the correct answer because it is the process of genetic transfer between bacteria that requires direct cell-to-cell contact. During conjugation, a donor bacterial cell transfers genetic material, such as plasmids, to a recipient cell through a conjugation bridge. This direct contact allows for the transfer of genetic information, including antibiotic resistance genes, between bacteria. Transfection, transformation, and transposons are not processes that involve cell-to-cell contact and are therefore not the correct answers.

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  • 15. 

    A gene on a strand of DNA has the following sequence T-C-A-A-A-G-T-T-T-G-G-A-A-G-G-C-T-T-A-G-T. The sequence of nucleotides that would be transcribed into mRNA is:

    • U-C-A-A-A-G-U-U-U-G-G-A-A-G-G-C-U-U-A-G-U

    • A-G-U-U-U-C-A-A-A-C-C-U-U-C-C-G-A-A-U-C-A

    • T-C-A-A-A-G-T-T-T-G-G-A-A-G-G-C-T-T-A-G-T

    • None of the above

    Correct Answer
    A. A-G-U-U-U-C-A-A-A-C-C-U-U-C-C-G-A-A-U-C-A
    Explanation
    The DNA sequence is transcribed into mRNA by replacing each DNA nucleotide with its complementary RNA nucleotide. In this case, the DNA sequence T-C-A-A-A-G-T-T-T-G-G-A-A-G-G-C-T-T-A-G-T would be transcribed into the mRNA sequence A-G-U-U-U-C-A-A-A-C-C-U-U-C-C-G-A-A-U-C-A.

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  • 16. 

    Agent which most specifically destroy bacteria are:

    • Oxidizers

    • Bactericidal

    • Germicides

    • Bacteriostatic

    Correct Answer
    A. Bactericidal
    Explanation
    Bactericidal agents are substances that specifically kill bacteria. Unlike bacteriostatic agents that only inhibit bacterial growth, bactericidal agents directly destroy bacteria. They can achieve this by disrupting the bacterial cell wall, interfering with essential metabolic processes, or targeting specific bacterial enzymes. By effectively killing bacteria, bactericidal agents are important in treating infections and preventing the spread of harmful bacteria.

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  • 17. 

    Thioglycollate acid (a reducing media) in a liquid medium supports the growth of ____ bacteria.

    • Obligate aerobic

    • Obligate anaerobic

    Correct Answer
    A. Obligate anaerobic
    Explanation
    Thioglycollate acid, being a reducing media, creates an environment that lacks oxygen. This type of environment is suitable for the growth of obligate anaerobic bacteria, which cannot survive in the presence of oxygen. Obligate anaerobic bacteria obtain energy through fermentation or anaerobic respiration, and they thrive in environments where oxygen is absent. Therefore, thioglycollate acid in a liquid medium supports the growth of obligate anaerobic bacteria.

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  • 18. 

    Glutaraldehyde is effective against:

    • Bacteria

    • Viruses

    • Fungi

    • All of these

    Correct Answer
    A. All of these
    Explanation
    Glutaraldehyde is a powerful disinfectant that is effective against bacteria, viruses, and fungi. It is commonly used in healthcare settings to sterilize medical equipment and surfaces. Its broad-spectrum activity makes it a versatile option for killing a wide range of microorganisms, including both bacteria and viruses. Additionally, it is also effective against fungi, making it a comprehensive solution for disinfection purposes.

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  • 19. 

    Microbicidal agents are more effective against _______ cells in a population.

    • Older

    • Younger

    Correct Answer
    A. Younger
    Explanation
    Microbicidal agents are more effective against younger cells in a population because younger cells tend to have a higher metabolic rate and are more actively dividing. This makes them more susceptible to the action of microbicidal agents, which can disrupt their cellular processes and kill them. Older cells, on the other hand, may have developed mechanisms to resist the effects of microbicidal agents or have a slower metabolic rate, making them less susceptible to these agents.

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  • 20. 

    Biosynthesis of DNA in bacterial cells occurs by _________ replication.

    • Conservative

    • Semi-conservative

    Correct Answer
    A. Semi-conservative
    Explanation
    The correct answer is semi-conservative. In semi-conservative replication, the two strands of the DNA molecule separate, and each strand serves as a template for the synthesis of a new complementary strand. This results in two daughter DNA molecules, each consisting of one original strand and one newly synthesized strand. This mechanism ensures that the genetic information is faithfully preserved and passed on to the next generation of bacterial cells.

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  • 21. 

    An organism that uses inorganic CO2  as its carbon source is an:

    • Heterotroph

    • Autotroph

    Correct Answer
    A. Autotroph
    Explanation
    An organism that uses inorganic CO2 as its carbon source is an autotroph because autotrophs are capable of synthesizing organic compounds from inorganic substances. They can convert CO2 into complex organic molecules through processes like photosynthesis. Heterotrophs, on the other hand, obtain their carbon from organic sources, such as consuming other organisms.

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  • 22. 

    Microorganisms that require a low level of oxygen for growth are:

    • Capnophiles

    • Anaerobes

    • Aerobes

    • Microaerophilic

    Correct Answer
    A. Microaerophilic
    Explanation
    Microaerophilic microorganisms require a low level of oxygen for growth. Unlike aerobes, which require higher levels of oxygen, microaerophiles thrive in environments with reduced oxygen concentrations. They are able to survive and grow in these conditions due to their specific adaptations to low oxygen levels, such as having efficient oxygen-scavenging enzymes.

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  • 23. 

    The codons in messenger RNA that specify amino acids in proteins are made up of:

    • Monosaccharides

    • Fatty acids

    • Amino acids

    • Nucleotide bases

    Correct Answer
    A. Nucleotide bases
    Explanation
    The codons in messenger RNA that specify amino acids in proteins are made up of nucleotide bases. Codons are the three-letter sequences of nucleotide bases (adenine, cytosine, guanine, and uracil) that determine the order of amino acids during protein synthesis. Each codon codes for a specific amino acid, and the sequence of codons determines the sequence of amino acids in a protein. Monosaccharides, fatty acids, and amino acids are not involved in the formation of codons in messenger RNA.

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  • 24. 

    Bacteria that require growth factors and complex nutrients in the medium are:

    • Holophiles

    • Acidophiles

    • Fastidious

    • Barophiles

    Correct Answer
    A. Fastidious
    Explanation
    Fastidious bacteria are those that have complex nutritional requirements and require the presence of specific growth factors in the medium in order to grow and reproduce. They are unable to synthesize certain essential nutrients on their own and rely on external sources for their growth. This makes them more demanding and selective in their nutritional needs compared to other bacteria.

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  • 25. 

    Human pathogenic bacteria are most likely to be _______ in their temperature requirements.

    • Thermophiles

    • Mesophiles

    • Psychrophiles

    • Acidophiles

    Correct Answer
    A. Mesophiles
    Explanation
    Mesophiles are the most likely temperature requirement for human pathogenic bacteria. Mesophiles thrive in moderate temperatures, typically between 20 to 45 degrees Celsius, which is the range commonly found in the human body. This makes mesophiles well-suited to survive and multiply in the human body, leading to infections and diseases. Thermophiles require high temperatures, psychrophiles thrive in cold temperatures, and acidophiles prefer acidic environments, but these temperature requirements are less likely to be found in the human body.

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  • 26. 

    Which of the following is not a technique used in the measurement of bacterial growth?

    • Turbidity

    • Radioimmunoassay

    • Coulter counter

    • Cell counts

    Correct Answer
    A. Radioimmunoassay
    Explanation
    Radioimmunoassay is not a technique used in the measurement of bacterial growth. This technique is primarily used to measure the concentration of specific substances, such as hormones or drugs, in biological samples. It involves the use of radioactive isotopes and specific antibodies to detect and quantify the target substance. However, it is not suitable for measuring bacterial growth, which typically involves methods like turbidity measurement, Coulter counter, and cell counts to assess the increase in bacterial population.

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  • 27. 

    Bacteria which require high concentrations of salt (NaCl) are:

    • Halophiles

    • Acidophiles

    • Alkalineophiles

    • Barophiles

    Correct Answer
    A. Halophiles
    Explanation
    Halophiles are bacteria that require high concentrations of salt (NaCl) to survive and thrive. They have adapted to live in environments such as salt lakes, salt pans, and salted food products. These bacteria have specific mechanisms to maintain osmotic balance and prevent dehydration in high salt conditions. They are capable of metabolizing and utilizing the salt as an energy source. Therefore, halophiles are the correct answer for bacteria that require high concentrations of salt.

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  • 28. 

    The term ______ refers to organisms living in an obligatory but mutually beneficial relationship.

    • Commensalism

    • Parasitism

    • Mutualism

    • Habituism

    Correct Answer
    A. Mutualism
    Explanation
    Mutualism refers to a relationship between two organisms in which both benefit from each other's presence. It is an obligatory and mutually beneficial relationship where both organisms rely on each other for survival and reproduction. In this type of relationship, both parties provide resources or services to each other, resulting in a positive outcome for both. This can include things like pollination, cleaning, or protection.

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  • 29. 

    Deep sea microbes that require increased hydrostatic pressure are:

    • Acidophiles

    • Alkalinophiles

    • Barophiles

    • Haolophiles

    Correct Answer
    A. Barophiles
    Explanation
    Barophiles are deep-sea microbes that require increased hydrostatic pressure to survive. These organisms have adapted to the extreme conditions of the deep ocean where pressure is significantly higher compared to the surface. They have developed unique mechanisms to withstand and even thrive under these high-pressure conditions. Barophiles are able to maintain their cell structure and function properly due to specialized adaptations in their cell membranes and enzymes. These adaptations allow them to survive and carry out essential biological processes in the deep-sea environment.

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  • 30. 

    The enzyme RNA polymerase is needed for the synthesis of:

    • RRNA

    • TRNA

    • DNA

    • MRNA

    Correct Answer
    A. MRNA
    Explanation
    RNA polymerase is an enzyme responsible for transcribing DNA into RNA. It binds to the DNA template strand and synthesizes a complementary mRNA molecule during the process of transcription. mRNA carries the genetic information from DNA to the ribosomes, where it is translated into proteins. Therefore, RNA polymerase is specifically needed for the synthesis of mRNA.

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  • 31. 

    Antibiotic resistance of bacteria is associated most commonly with:

    • Bateriophages

    • Plasmids

    • Spheroplasts

    • Protoplasts

    Correct Answer
    A. Plasmids
    Explanation
    Antibiotic resistance of bacteria is most commonly associated with plasmids. Plasmids are small, circular DNA molecules that can be transferred between bacteria. They often carry genes that provide resistance to antibiotics, allowing bacteria to survive and multiply in the presence of these drugs. This transfer of resistance genes through plasmids contributes to the spread of antibiotic resistance among bacterial populations, making plasmids a major factor in the development of antibiotic-resistant bacteria.

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  • 32. 

    The time required for sterilization of objects in a steam autoclave is _______ at 15 p.s.i. for _____ minutes

    • 100 deg C / 10 min

    • 121 deg C / 20 min

    • 121 deg C / 30 min

    • 100 deg C / 12 min

    Correct Answer
    A. 121 deg C / 20 min
    Explanation
    The correct answer is 121 deg C / 20 min. Sterilization in a steam autoclave requires a combination of temperature and time to effectively kill microorganisms. The temperature of 121 deg C is necessary to ensure the destruction of heat-resistant spores, while a duration of 20 minutes allows for adequate exposure to the high temperature. This combination provides the optimal conditions for sterilization in a steam autoclave.

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  • 33. 

    In a _______ mutation the normal codon is changed into a stop codon.

    • Neutral

    • Nonsense

    • Missense

    • Dissense

    Correct Answer
    A. Nonsense
    Explanation
    A nonsense mutation refers to a type of genetic mutation where the normal codon in the DNA sequence is changed into a stop codon. This stop codon signals the termination of protein synthesis, resulting in a truncated and nonfunctional protein. Unlike neutral mutations, which have no effect on the protein's function, nonsense mutations can have significant consequences as they disrupt the normal protein structure and function. Missense mutations, on the other hand, involve the substitution of one amino acid for another, while dissense mutations are not recognized terms in genetics.

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  • 34. 

    The _____ is the time required to kill all microbes at a specified temperature.

    • Thermal death time

    • Thermal death point

    • Thermal heat time

    • None of the above

    Correct Answer
    A. Thermal death time
    Explanation
    The term "thermal death time" refers to the amount of time it takes to completely kill off all microbes at a specific temperature. It is a measure of the effectiveness of heat in destroying microorganisms. This term is commonly used in microbiology and food safety to determine the appropriate temperature and duration for processes such as pasteurization or sterilization. The other options, "thermal death point" and "thermal heat time," do not accurately describe this concept.

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  • 35. 

    The process of _____ prevents any genes in an operon that code for amino acids from being transcribed into messenger RNA.

    • Induction

    • Allosteric inhibition

    • Repression

    • Hybridization

    Correct Answer
    A. Repression
    Explanation
    Repression is the process that prevents any genes in an operon that code for amino acids from being transcribed into messenger RNA. Repression occurs when a repressor protein binds to the operator region of the operon, blocking the RNA polymerase from binding to the promoter and initiating transcription. This mechanism allows the cell to regulate gene expression and prevent the production of unnecessary amino acids when they are not needed.

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  • 36. 

    The enzyme which is used to produce complentary DNA (cDNA) from messenger RNA is a:

    • Gyrase

    • Polymerase

    • Reverse transcriptase

    • Endonuclease

    Correct Answer
    A. Reverse transcriptase
    Explanation
    Reverse transcriptase is the correct answer because it is an enzyme that is used to produce complementary DNA (cDNA) from messenger RNA. This process is known as reverse transcription, where the enzyme synthesizes a DNA strand using the mRNA as a template. Reverse transcriptase is commonly used in molecular biology research to study gene expression and create cDNA libraries. It plays a crucial role in understanding the genetic information encoded in mRNA molecules.

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  • 37. 

    The process of decontamination of living tissue to reduce the microbial population is called:

    • Sanitization

    • Degermination

    Correct Answer
    A. Degermination
    Explanation
    Degermination is the correct answer because it refers to the process of removing or reducing the number of microorganisms from living tissue. Sanitization, on the other hand, refers to the process of reducing the number of microorganisms on inanimate objects or surfaces. Therefore, degermination is the more appropriate term for the decontamination of living tissue.

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  • 38. 

    The process whereby amino acids are assembled into proteins on the ribosomes is called:

    • Hybridization

    • Transcription

    • Translation

    • Recombination

    Correct Answer
    A. Translation
    Explanation
    Translation is the correct answer because it refers to the process in which amino acids are assembled into proteins on the ribosomes. During translation, the ribosomes read the messenger RNA (mRNA) sequence and use it as a template to link amino acids together in the correct order, forming a polypeptide chain which eventually folds into a functional protein. Hybridization is a process of combining two complementary nucleic acid strands, transcription is the synthesis of RNA from a DNA template, and recombination involves the rearrangement of genetic material.

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  • 39. 

    A modified recombinant plasmid is placed into recipient bacteria by the process of:

    • Conjugation

    • Hybridization

    • Mutation

    • Transformation

    Correct Answer
    A. Transformation
    Explanation
    Transformation is the process by which foreign DNA is introduced into a recipient cell. In this case, a modified recombinant plasmid is being placed into recipient bacteria, indicating that the DNA is being transferred from one organism to another. Conjugation involves the transfer of DNA through direct cell-to-cell contact, hybridization refers to the joining of complementary DNA strands, and mutation is a random change in DNA sequence. Therefore, transformation is the most appropriate process for the introduction of the modified recombinant plasmid into the recipient bacteria.

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  • 40. 

    A bacterial virus transfers small pieces of DNA from donor to recipient bacteria by:

    • Conjugation

    • Transformation

    • Transduction

    • Transposons

    Correct Answer
    A. Transduction
    Explanation
    Transduction is the process by which a bacterial virus, also known as a bacteriophage, transfers small pieces of DNA from a donor bacterium to a recipient bacterium. During transduction, the bacteriophage infects the donor bacterium and incorporates fragments of the donor's DNA into its own viral DNA. When the bacteriophage infects a recipient bacterium, it injects this viral DNA, which can then be integrated into the recipient's genome. This transfer of genetic material allows for the spread of specific genes between bacteria, contributing to genetic diversity and adaptation.

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  • 41. 

    Which of the following is a useful household disinfectant?

    • 30% ethyl alcohol

    • 5% silver nitrate

    • 5% sodium hypochlorite

    • 5% phenol

    Correct Answer
    A. 5% sodium hypochlorite
    Explanation
    Sodium hypochlorite is a useful household disinfectant because it is effective in killing a wide range of bacteria, viruses, and fungi. It is commonly used as a bleach and can be diluted to a 5% solution for disinfection purposes. Ethyl alcohol is not as effective as sodium hypochlorite in killing certain types of microorganisms. Silver nitrate is primarily used for its antimicrobial properties in medical settings, and phenol is a disinfectant that is more commonly used in industrial or laboratory settings.

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  • 42. 

    Which of the following substances can be used to disinfect water?

    • Carbolic acid

    • Aldehydes

    • Iodine

    • Hydrogen peroxide

    Correct Answer
    A. Iodine
    Explanation
    Iodine can be used to disinfect water because it has strong antimicrobial properties. When iodine is added to water, it reacts with microorganisms, such as bacteria and viruses, and destroys their cell membranes, effectively killing them. This makes iodine an effective disinfectant for water purification, especially in situations where access to clean water is limited or during emergencies.

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  • 43. 

    The best method for sterilizing serum and other blood products is:

    • Steam autoclave

    • Hot air oven

    • Filtration

    • Boiling

    Correct Answer
    A. Filtration
    Explanation
    Filtration is the best method for sterilizing serum and other blood products because it effectively removes bacteria, viruses, and other microorganisms from the liquid. This method involves passing the serum through a filter with small pores that can trap and remove these contaminants. Filtration is a reliable and efficient technique that ensures the safety and purity of the blood products without the need for high temperatures or chemicals that could potentially alter their composition or effectiveness.

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  • 44. 

    The most abundant component of a microbial cell is __________.

    • Sugar

    • Lipids

    • Water

    • Proteins

    Correct Answer
    A. Water
    Explanation
    The most abundant component of a microbial cell is water. Water makes up a significant portion of the cell's mass and is essential for various cellular processes such as metabolism, transportation, and maintaining cell structure. It acts as a solvent for many biochemical reactions and provides a medium for the transport of nutrients and waste products. Additionally, water is involved in maintaining the cell's internal temperature and pH balance. Therefore, water is a crucial component of microbial cells.

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  • 45. 

    An enzyme which cleaves DNA to produce sticky end fragments is called a:

    • Ligase

    • Endonuclease

    • Isomerase

    • Oxidoreductase

    Correct Answer
    A. Endonuclease
    Explanation
    An enzyme that cleaves DNA to produce sticky end fragments is called an endonuclease. Endonucleases are responsible for cutting DNA at specific sites within the molecule, resulting in fragments with sticky ends that can easily join with complementary DNA fragments. Ligase, isomerase, and oxidoreductase are not involved in the cleavage of DNA.

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  • 46. 

    Chemical agents called surfactants act on the microorganism's _________.

    • Proteins

    • Cell wall

    • Cell membranes

    • Nucleic acids

    Correct Answer
    A. Cell membranes
    Explanation
    Surfactants are chemical agents that are known to act on cell membranes. They have the ability to disrupt the structure and function of cell membranes, leading to the destruction of microorganisms. This disruption can cause leakage of cellular contents and ultimately result in the death of the microorganism. Therefore, cell membranes are the target of surfactants in their action against microorganisms.

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  • 47. 

    Alcohol is effective against:

    • Bacterial spores

    • Enveloped viruses

    • Vegetative bacterial cells

    • All of these

    Correct Answer
    A. Vegetative bacterial cells
    Explanation
    Alcohol is effective against vegetative bacterial cells because it has the ability to denature proteins and disrupt the cell membranes of bacteria. This leads to the destruction of bacterial cells and prevents their growth and reproduction. However, alcohol may not be effective against bacterial spores, which have a protective outer layer that makes them more resistant to disinfection. Additionally, alcohol is also effective against enveloped viruses, which have a lipid envelope that can be easily disrupted by alcohol, rendering the virus inactive.

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  • 48. 

    Genes that code for repressor proteins in bacteria operons are called:

    • Regulator genes

    • Repressor genes

    • Operator genes

    • Structural genes

    Correct Answer
    A. Regulator genes
    Explanation
    Regulator genes are the correct answer because they code for repressor proteins in bacterial operons. These repressor proteins bind to the operator region of the operon and prevent the transcription of structural genes. By regulating the expression of structural genes, regulator genes play a crucial role in controlling gene expression in bacteria.

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  • 49. 

    The non-specific direct transfer of "naked" DNA from a donor bacterial cell to a recipient bacterial cell is:

    • Transduction

    • Conjugation

    • Transformation

    • Transfusion

    Correct Answer
    A. Transformation
    Explanation
    Transformation is the correct answer because it refers to the non-specific direct transfer of "naked" DNA from a donor bacterial cell to a recipient bacterial cell. Transduction involves the transfer of DNA through a bacteriophage, conjugation involves the transfer of DNA through direct cell-to-cell contact, and transfusion is the transfer of blood or blood components from one individual to another.

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  • Mar 20, 2023
    Quiz Edited by
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  • May 11, 2010
    Quiz Created by
    Larainahailey
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