Bacterial Growth & Metabolism
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All Questions for: Bacterial Growth & Metabolism
Question 1: Binary fission is the process by which bacteria:
- A Reproduce asexually
- B Transfer DNA
- C Form spores
- D Become dormant
Explanation: Binary fission is asexual reproduction producing two identical daughter cells.
Question 2: The bacterial growth curve has how many phases?
- A Four
- B Three
- C Five
- D Two
Explanation: The bacterial growth curve has four phases: lag, log (exponential), stationary, and death.
Question 3: During which phase do bacteria grow fastest?
- A Log (exponential) phase
- B Lag phase
- C Stationary phase
- D Death phase
Explanation: Log (exponential) phase is when bacteria grow and divide at maximum rate.
Question 4: In the lag phase, bacteria:
- A Adapt without dividing
- B Divide rapidly
- C Die
- D Form spores
Explanation: During lag phase, bacteria adapt to new conditions but do not divide.
Question 5: In the stationary phase:
- A Growth rate equals death rate
- B Bacteria divide fastest
- C All bacteria die
- D Bacteria form spores only
Explanation: Stationary phase occurs when growth rate equals death rate, so total cell number stays constant.
Question 6: Generation time is:
- A Time for population to double
- B Time to form spores
- C Time to transfer DNA
- D Time to become dormant
Explanation: Generation time is the time required for a bacterial population to double.
Question 7: Bacteria that grow best at human body temperature are:
- A Mesophiles
- B Psychrophiles
- C Thermophiles
- D Hyperthermophiles
Explanation: Mesophiles grow best at moderate temperatures (20–45°C), like human body temperature.
Question 8: Psychrophiles grow best at:
- A Cold temperatures (<15°C)
- B Body temperature
- C High temperatures (>60°C)
- D Neutral pH
Explanation: Psychrophiles thrive at cold temperatures (below 15°C).
Question 9: Thermophiles grow best at:
- A High temperatures (45–80°C)
- B Cold temperatures
- C Body temperature
- D Low pH
Explanation: Thermophiles thrive at high temperatures (45–80°C).
Question 10: Bacteria that require oxygen for growth are called:
- A Obligate aerobes
- B Obligate anaerobes
- C Facultative anaerobes
- D Microaerophiles
Explanation: Obligate aerobes require oxygen; obligate anaerobes are killed by oxygen.
Question 11: Bacteria killed by oxygen are:
- A Obligate anaerobes
- B Obligate aerobes
- C Facultative anaerobes
- D Aerotolerant anaerobes
Explanation: Obligate anaerobes cannot survive in the presence of oxygen.
Question 12: Facultative anaerobes:
- A Grow with or without oxygen
- B Require oxygen
- C Are killed by oxygen
- D Require CO2
Explanation: Facultative anaerobes can grow with or without oxygen.
Question 13: Bacterial metabolism that uses oxygen as final electron acceptor is:
- A Aerobic respiration
- B Anaerobic respiration
- C Fermentation
- D Photosynthesis
Explanation: Aerobic respiration uses oxygen as the final electron acceptor.
Question 14: Fermentation in bacteria produces:
- A ATP without oxygen
- B Only oxygen
- C Only water
- D Only glucose
Explanation: Fermentation produces ATP without oxygen, generating products like lactic acid, ethanol, or acetic acid.
Question 15: Which bacteria are used in yogurt production?
- A Lactobacillus and Streptococcus
- B E. coli and Salmonella
- C Clostridium and Bacillus
- D Mycobacterium and Corynebacterium
Explanation: Lactobacillus and Streptococcus species ferment milk into yogurt.
Question 16: Nitrogen-fixing bacteria convert:
- A N2 to ammonia
- B Ammonia to N2
- C Nitrate to N2
- D N2 to nitrate
Explanation: Nitrogen-fixing bacteria (e.g., Rhizobium) convert atmospheric N2 into ammonia.
Question 17: Rhizobium bacteria form symbiotic relationships with:
- A Legume roots
- B Animal intestines
- C Fish gills
- D Human skin
Explanation: Rhizobium forms nodules on legume roots for nitrogen fixation.
Question 18: Which is a selective medium for Gram-negative bacteria?
- A MacConkey agar
- B Blood agar
- C Nutrient agar
- D Chocolate agar
Explanation: MacConkey agar inhibits Gram-positive bacteria and allows Gram-negative growth.
Question 19: Blood agar is classified as:
- A Enriched and differential
- B Selective only
- C Defined medium
- D Minimal medium
Explanation: Blood agar is an enriched, differential medium showing hemolysis patterns.
Question 20: Autoclaving uses which combination for sterilization?
- A High-pressure steam
- B Dry heat
- C UV light
- D Filtration
Explanation: Autoclaving uses high-pressure steam (121°C, 15 psi) for 15–20 minutes.
Question 21: Pasteurization uses:
- A Controlled heating to kill pathogens
- B High-pressure steam
- C UV light
- D Radiation
Explanation: Pasteurization heats liquids (e.g., milk) to kill pathogens without sterilizing.
Question 22: A bacterial colony arises from:
- A A single cell
- B Multiple cells
- C A spore
- D A virus
Explanation: Each colony arises from a single bacterial cell (or CFU — colony-forming unit).
Question 23: CFU stands for:
- A Colony-Forming Unit
- B Cell Fusion Unit
- C Cellular Function Unit
- D Culture Fast Unit
Explanation: CFU stands for Colony-Forming Unit, a measure of viable bacterial numbers.
Question 24: Viable plate count measures:
- A Living bacteria
- B Total bacteria including dead
- C Bacterial DNA
- D Bacterial proteins
Explanation: Viable plate count measures living (viable) bacteria that can form colonies.
Question 25: Antibiotic resistance can spread between bacteria via:
- A Horizontal gene transfer
- B Binary fission only
- C Spore formation
- D Capsule formation
Explanation: Resistance spreads via horizontal gene transfer: conjugation, transformation, and transduction.