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TestMaster MCQs

Bacterial Growth & Metabolism Questions

Home Science Bacterial Growth & Metabolism
Q. Binary fission is the process by which bacteria:
Become dormant
Transfer DNA
Reproduce asexually
Form spores

Explanation:

Binary fission is asexual reproduction producing two identical daughter cells.

Q. The bacterial growth curve has how many phases?
Two
Five
Four
Three

Explanation:

The bacterial growth curve has four phases: lag, log (exponential), stationary, and death.

Q. During which phase do bacteria grow fastest?
Log (exponential) phase
Death phase
Stationary phase
Lag phase

Explanation:

Log (exponential) phase is when bacteria grow and divide at maximum rate.

Q. In the lag phase, bacteria:
Divide rapidly
Die
Form spores
Adapt without dividing

Explanation:

During lag phase, bacteria adapt to new conditions but do not divide.

Q. In the stationary phase:
Growth rate equals death rate
Bacteria form spores only
All bacteria die
Bacteria divide fastest

Explanation:

Stationary phase occurs when growth rate equals death rate, so total cell number stays constant.

Q. Generation time is:
Time to form spores
Time to transfer DNA
Time to become dormant
Time for population to double

Explanation:

Generation time is the time required for a bacterial population to double.

Q. Bacteria that grow best at human body temperature are:
Mesophiles
Hyperthermophiles
Psychrophiles
Thermophiles

Explanation:

Mesophiles grow best at moderate temperatures (20–45°C), like human body temperature.

Q. Psychrophiles grow best at:
High temperatures (>60°C)
Neutral pH
Body temperature
Cold temperatures (<15°C)

Explanation:

Psychrophiles thrive at cold temperatures (below 15°C).

Q. Thermophiles grow best at:
Body temperature
Cold temperatures
Low pH
High temperatures (45–80°C)

Explanation:

Thermophiles thrive at high temperatures (45–80°C).

Q. Bacteria that require oxygen for growth are called:
Obligate anaerobes
Obligate aerobes
Facultative anaerobes
Microaerophiles

Explanation:

Obligate aerobes require oxygen; obligate anaerobes are killed by oxygen.

Q. Bacteria killed by oxygen are:
Facultative anaerobes
Aerotolerant anaerobes
Obligate aerobes
Obligate anaerobes

Explanation:

Obligate anaerobes cannot survive in the presence of oxygen.

Q. Facultative anaerobes:
Require oxygen
Grow with or without oxygen
Are killed by oxygen
Require CO2

Explanation:

Facultative anaerobes can grow with or without oxygen.

Q. Bacterial metabolism that uses oxygen as final electron acceptor is:
Aerobic respiration
Anaerobic respiration
Photosynthesis
Fermentation

Explanation:

Aerobic respiration uses oxygen as the final electron acceptor.

Q. Fermentation in bacteria produces:
Only water
Only oxygen
Only glucose
ATP without oxygen

Explanation:

Fermentation produces ATP without oxygen, generating products like lactic acid, ethanol, or acetic acid.

Q. Which bacteria are used in yogurt production?
Clostridium and Bacillus
Lactobacillus and Streptococcus
Mycobacterium and Corynebacterium
E. coli and Salmonella

Explanation:

Lactobacillus and Streptococcus species ferment milk into yogurt.

Q. Nitrogen-fixing bacteria convert:
N2 to ammonia
Ammonia to N2
N2 to nitrate
Nitrate to N2

Explanation:

Nitrogen-fixing bacteria (e.g., Rhizobium) convert atmospheric N2 into ammonia.

Q. Rhizobium bacteria form symbiotic relationships with:
Human skin
Fish gills
Animal intestines
Legume roots

Explanation:

Rhizobium forms nodules on legume roots for nitrogen fixation.

Q. Which is a selective medium for Gram-negative bacteria?
Chocolate agar
Nutrient agar
Blood agar
MacConkey agar

Explanation:

MacConkey agar inhibits Gram-positive bacteria and allows Gram-negative growth.

Q. Blood agar is classified as:
Selective only
Defined medium
Minimal medium
Enriched and differential

Explanation:

Blood agar is an enriched, differential medium showing hemolysis patterns.

Q. Autoclaving uses which combination for sterilization?
Dry heat
UV light
High-pressure steam
Filtration

Explanation:

Autoclaving uses high-pressure steam (121°C, 15 psi) for 15–20 minutes.

Q. Pasteurization uses:
Controlled heating to kill pathogens
Radiation
UV light
High-pressure steam

Explanation:

Pasteurization heats liquids (e.g., milk) to kill pathogens without sterilizing.

Q. A bacterial colony arises from:
A spore
A single cell
Multiple cells
A virus

Explanation:

Each colony arises from a single bacterial cell (or CFU — colony-forming unit).

Q. CFU stands for:
Cell Fusion Unit
Colony-Forming Unit
Culture Fast Unit
Cellular Function Unit

Explanation:

CFU stands for Colony-Forming Unit, a measure of viable bacterial numbers.

Q. Viable plate count measures:
Bacterial proteins
Living bacteria
Total bacteria including dead
Bacterial DNA

Explanation:

Viable plate count measures living (viable) bacteria that can form colonies.

Q. Antibiotic resistance can spread between bacteria via:
Horizontal gene transfer
Binary fission only
Capsule formation
Spore formation

Explanation:

Resistance spreads via horizontal gene transfer: conjugation, transformation, and transduction.

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