MDCAT Prokaryotes MCQs

1. The basic unit of life in prokaryotes is called a:

A) Cell
B) Tissue
C) Organ
D) Organism

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2. The outermost layer of a bacterial cell is known as the:

A) Cell m
B) Cytoplasm
C) Cell wall
D) Nucleus

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3. Which of the following structures is NOT found in prokaryotic cells?

A) Nucleus
B) Ribosomes
C) Cell membrane
D) Cell wall

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4. The jelly-like substance inside a bacterial cell is called:

A) Nucleoid
B) Cytoplasm
C) Ribosomes
D) Capsule

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5. What is the function of the bacterial cell wall?

A) Control transport
B) Provide shape and protection
C) Store genetic material
D) Produce energy

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6. Bacteria are classified as prokaryotes because they lack:

A) DNA
B) A cell membrane
C) A nucleus
D) Ribosomes

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7. The region in a prokaryotic cell where the genetic material is located is called the:

A) Nucleus
B) Nucleoid
C) Cytoplasm
D) Ribosome

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8. Which of the following is NOT a function of the plasma membrane in bacteria?

A) Transport of materials
B) Energy production
C) Genetic information storage
D) Cell signaling

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9. Bacteria can have a structure called a flagellum, which is used for:

A) Respiration
B) Photosynthesis
C) Locomotion
D) Reproduction

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10. Which of the following is a structure that helps bacteria adhere to surfaces?

A) Capsule
B) Flagellum
C) Pilus
D) Ribosome

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11. Bacteria are commonly classified into different shapes. Which of the following is NOT a common bacterial shape?

A) Cocci
B) Bacilli
C) Spirilla
D) Amoebae

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12. Cocci bacteria are shaped like:

A) Rods
B) Spheres
C) Spirals
D) Chains

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13. Which shape of bacteria is described as rod-shaped?

A) Cocci
B) Bacilli
C) Spirilla
D) Vibrio

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14. The term “vibrio” refers to bacteria that are:

A) Spherical
B) Rod-shaped
C) Comma-shaped
D) Spiral-shaped

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15. The size of most bacteria typically ranges from:

A) 0.1 to 10 micrometers
B) 1 to 100 micrometers
C) 10 to 1000 micrometers
D) 100 to 1000 micrometers

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16. Which of the following bacterial shapes can occur in chains?

A) Cocci
B) Bacilli
C) Spirilla
D) Both A and B

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17. The term “streptococci” refers to:

A) Cocci that occur in clusters
B) Bacilli that occur in chains
C) Cocci that occur in chains
D) Bacilli that occur singly

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18. Which type of bacteria is known for having a spiral shape?

A) Bacilli
B) Cocci
C) Spirilla
D) Vibrio

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19. The shape of bacteria can influence their:

A) Metabolism
B) Reproduction
C) Pathogenicity
D) All of the above

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20. Bacterial size can be measured in:

A) Millimeters
B) Micrometers
C) Nanometers
D) Centimeters

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21. Which of the following is a beneficial role of bacteria in the environment?

A) Nitrogen fixation
B) Pathogenic infections
C) Water pollution
D) Food spoilage

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22. Bacteria are essential for:

A) Decomposition
B) Photosynthesis
C) Mineral formation
D) All of the above

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23. Which of the following processes is carried out by certain bacteria in the nitrogen cycle?

A) Denitrification
B) Photosynthesis
C) Fermentation
D) Respiration

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24. Bacteria can be used in biotechnology for:

A) Genetic engineering
B) Antibiotic production
C) Bioremediation
D) All of the above

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25. Some bacteria are used in the production of:

A) Yogurt
B) Cheese
C) Sauerkraut
D) All of the above

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26. Pathogenic bacteria can cause diseases in:

A) Humans
B) Animals
C) Plants
D) All of the above

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27. Bacteria are used in sewage treatment to:

A) Decompose organic waste
B) Increase water purity
C) Produce methane
D) All of the above

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28. Bacteria play a crucial role in soil health by:

A) Enhancing nutrient availability
B) Competing with weeds
C) Preventing erosion
D) Reducing water retention

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29. Which of the following bacteria is commonly used in the production of antibiotics?

A) Escherichia coli
B) Streptomyces
C) Lactobacillus
D) Bacillus subtilis

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30. The role of bacteria in the human gut is primarily to:

A) Aid in digestion
B) Cause infections
C) Produce hormones
D) Absorb nutrients

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31. Antibiotics are used to:

A) Promote bacterial growth
B) Kill or inhibit the growth of bacteria
C) Enhance digestion
D) Prevent viral infections

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32. Which of the following is a common method for controlling bacterial growth in food?

A) Freezing
B) Boiling
C) Canning
D) All of the above

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33. Disinfectants are used to:

A) Promote bacterial growth
B) Kill bacteria on surfaces
C) Increase bacterial reproduction
D) Enhance soil quality

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34. What is one potential problem associated with the overuse of antibiotics?

A) Increased bacterial diversity
B) Antibiotic resistance
C) Enhanced immune response
D) Decreased pathogenicity

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35. The process of sterilization is used to:

A) Kill all microorganisms
B) Promote bacterial growth
C) Selectively kill certain bacteria
D) Increase nutrient levels

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36. Bacteriophages are:

A) Antibiotics
B) Viruses that infect bacteria
C) Types of bacteria
D) Fungi that kill bacteria

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37. Which of the following methods is NOT effective for controlling bacterial growth?

A) Heating
B) Freezing
C) Refrigeration
D) Increasing oxygen levels

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38. The use of vaccines can help control diseases caused by:

A) Bacteria
B) Viruses
C) Fungi
D) All of the above

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39. Bacterial cultures are commonly stored in laboratories at:

A) High temperatures
B) Room temperature
C) Low temperatures
D) Under pressure

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40. Which of the following is a natural method for controlling harmful bacteria?

A) Probiotics
B) Antibiotics
C) Chemical disinfectants
D) Sterilization

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41. Bacterial reproduction primarily occurs through a process called:

A) Mitosis
B) Meiosis
C) Binary fission
D) Budding

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42. Which structure is responsible for genetic exchange between bacteria?

A) Cell wall
B) Plasmid
C) Nucleoid
D) Capsule

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43. The term “biofilm” refers to:

A) A single-celled organism
B) A thin layer of bacteria on a surface
C) Bacteria in a dormant state
D) The genetic material of bacteria

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44. Which of the following is an example of a beneficial bacterium?

A) Salmonella
B) E. coli (strain K-12)
C) Streptococcus pneumoniae
D) Mycobacterium tuberculosis

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45. Which process describes the transfer of genetic material between bacteria through direct contact?

A) Transformation
B) Conjugation
C) Transduction
D) Mutation

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46. The Gram stain is used to:

A) Determine bacterial shape
B) Identify bacterial species
C) Classify bacteria based on cell wall composition
D) Measure bacterial growth

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47. Bacteria that thrive in extreme environments are called:

A) Mesophiles
B) Psychrophiles
C) Thermophiles
D) Halophiles

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48. The thick peptidoglycan layer is characteristic of:

A) Gram-positive bacteria
B) Gram-negative bacteria
C) Both A and B
D) Neither A nor B

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49. Bacteria that require oxygen for growth are classified as:

A) Anaerobic
B) Aerobic
C) Facultative anaerobes
D) Microaerophiles

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50. Which of the following methods can be used to identify bacteria?

A) Biochemical tests
B) Microscopy
C) Culture methods
D) All of the above

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51. Which of the following structures helps bacteria resist phagocytosis?

A) Pilus
B) Capsule
C) Flagellum
D) Nucleoid

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52. Which of the following is a method for controlling bacterial contamination in laboratories?

A) Aseptic technique
B) Plating on agar
C) Cooling samples
D) All of the above

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53. The endospore is a:

A) Type of cell division
B) A dormant and resistant structure
C) A type of bacteria
D) A method of genetic exchange

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54. The term “antimicrobial” refers to substances that:

A) Promote bacterial growth
B) Kill or inhibit the growth of microorganisms
C) Are produced by viruses
D) Increase nutrient absorption

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55. The genetic material of bacteria is composed of:

A) Double-stranded DNA
B) Single-stranded RNA
C) Circular DNA
D) Linear DNA

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56. What type of bacteria is known to cause foodborne illness?

A) Lactobacillus
B) Clostridium botulinum
C) Streptococcus thermophilus
D) Escherichia coli (strain K-12)

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57. Bacteria that can survive without oxygen are known as:

A) Aerobic
B) Anaerobic
C) Microaerophilic
D) All of the above

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58. Which of the following is used in the lab to culture bacteria?

A) Agar plates
B) Broth media
C) Petri dishes
D) All of the above

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59. Which of the following is a feature of Gram-negative bacteria?

A) Thick peptidoglycan layer
B) Outer membrane
C) No cell wall
D) Always pathogenic

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60. The use of probiotics can help:

A) Increase harmful bacteria
B) Restore beneficial bacteria
C) Enhance viral infections
D) Increase antibiotic resistance

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61. Which of the following bacteria are commonly used in yogurt production?

A) Streptococcus thermophilus
B) Bacillus cereus
C) Staphylococcus aureus
D) Escherichia coli

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62. The term “pathogenic bacteria” refers to:

A) Bacteria that cause disease
B) Bacteria that are beneficial
C) Bacteria that are used in food production
D) Bacteria that are found in soil

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63. Biofilms are formed when:

A) Bacteria die
B) Bacteria reproduce
C) Bacteria adhere to surfaces and multiply
D) Bacteria absorb nutrients

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64. Bacteria that can switch between aerobic and anaerobic metabolism are called:

A) Obligate aerobes
B) Obligate anaerobes
C) Facultative anaerobes
D) Microaerophiles

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65. The role of pili in bacteria includes:

A) Movement
B) Genetic exchange
C) Protection
D) Nutrient absorption

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66. Which type of bacteria is capable of nitrogen fixation?

A) Nitrosomonas
B) Rhizobium
C) Escherichia coli
D) Streptococcus

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67. The process by which bacteria can take up DNA from their environment is called:

A) Conjugation
B) Transduction
C) Transformation
D) Binary fission

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68. Which of the following is a method to preserve food by inhibiting bacterial growth?

A) Pasteurization
B) Fermentation
C) Freezing
D) All of the above

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69. The primary component of a bacterial cell wall is:

A) Cellulose
B) Chitin
C) Peptidoglycan
D) Lipid

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70. Bacteria can be classified based on their:

A) Morphology
B) Metabolism
C) Habitat
D) All of the above

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71. Which of the following bacterial structures aids in motility?

A) Capsule
B) Pilus
C) Flagellum
D) Ribosome

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72. The enzyme that allows bacteria to digest complex carbohydrates is:

A) Amylase
B) Cellulase
C) Protease
D) All of the above

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73. Which process do bacteria use to obtain energy from organic compounds?

A) Photosynthesis
B) Fermentation
C) Cellular respiration
D) Both B and C

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74. Bacterial diseases can often be prevented through:

A) Vaccination
B) Antibiotic treatment
C) Hand hygiene
D) All of the above

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75. The outer membrane of Gram-negative bacteria is primarily composed of:

A) Lipopolysaccharides
B) Proteins
C) Nucleic acids
D) Carbohydrates

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76. Which type of bacteria primarily thrive in high-salt environments?

A) Psychrophiles
B) Halophiles
C) Thermophiles
D) Mesophiles

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77. Bacteria that live in extreme temperatures are known as:

A) Psychrophiles
B) Mesophiles
C) Thermophiles
D) Halophiles

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78. Bacteria can form spores to:

A) Reproduce quickly
B) Protect themselves from adverse conditions
C) Obtain nutrients
D) Increase size

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79. Which structure helps bacteria exchange genetic material during conjugation?

A) Capsule
B) Flagellum
C) Pilus
D) Cell wall

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80. Which of the following is a common laboratory technique for counting bacteria?

A) Hemocytometer
B) PCR
C) Gel electrophoresis
D) Spectrophotometry
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81. Bacteria that can survive in both aerobic and anaerobic conditions are termed:

A) Obligate aerobes
B) Obligate anaerobes
C) Faculative anaerobes
D) Microaerophiles

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82. Bacterial capsules are primarily made of:

A) Lipids
B) Proteins
C) Polysaccharides
D) Nucleic acids

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83. Bacteria are classified under Kingdom Monera, which is characterized by:

A) Multicellularity
B) Eukaryotic cells
C) Prokaryotic cells
D) Autotrophy

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84. Antibiotic resistance in bacteria can result from:

A) Genetic mutations
B) Plasmid exchange
C) Overuse of antibiotics
D) All of the above

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85. Which of the following bacteria is known to be a common cause of food poisoning?

A) Lactobacillus
B) Salmonella
C) Streptococcus
D) Clostridium thermocellum

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86. Bacterial transformation can be enhanced by:

A) Heat shock
B) Electroporation
C) Chemical treatment
D) All of the above

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87. The bacterial genome is typically composed of:

A) Linear DNA
B) Circular DNA
C) Plasmids
D) Both B and C

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88. Antibiotics function by targeting:

A) Host cells
B) Viral components
C) Bacterial cell structures or functions
D) All of the above

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89. Which bacterial group is responsible for nitrogen fixation in root nodules?

A) Bacillus
B) Rhizobium
C) Clostridium
D) Pseudomonas

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90. Bacterial contamination in drinking water is typically monitored by testing for:

A) Fungi
B) Viruses
C) Coliform bacteria
D) Algae

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91. The method of using high temperatures to kill bacteria in food is called:

A) Refrigeration
B) Pasteurization
C) Freezing
D) Fermentation

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92. Which of the following factors can influence bacterial growth?

A) Temperature
B) pH levels
C) Nutrient availability
D) All of the above

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93. The primary goal of sterilization is to:

A) Reduce microbial numbers
B) Kill all microorganisms
C) Enhance food quality
D) Increase bacterial diversity

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94. The bacteria involved in the spoilage of food are typically:

A) Pathogenic
B) Non-pathogenic
C) Beneficial
D) All of the above

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95. The study of bacteria is known as:

A) Virology
B) Mycology
C) Bacteriology
D) Parasitology

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96. Which of the following is a common test for determining bacterial sensitivity to antibiotics?

A) Gram stain
B) Biochemical test
C) Disk diffusion method
D) PCR

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97. Bioengineering often utilizes bacteria to:

A) Produce proteins
B) Degrade pollutants
C) Create insulin
D) All of the above

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98. The use of bacteriophages for treatment is an example of:

A) Antibiotic therapy
B) Phage therapy
C) Immunotherapy
D) Chemotherapy

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99. Which of the following is a characteristic of archaea, a group within Kingdom Monera?

A) Presence of peptidoglycan in cell walls
B) Extreme environmental adaptations
C) Obligate pathogenicity
D) Eukaryotic cell structure

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100. The main role of bacteria in the ecosystem includes:

A) Decomposition
B) Nutrient cycling
C) Symbiosis with plants
D) All of the above

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