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TestMaster MCQs

Bacterial Growth & Metabolism Questions

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

Explanation:

Binary fission is asexual reproduction producing two identical daughter cells.

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

Explanation:

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

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

Explanation:

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

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

Explanation:

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

Q. In the stationary phase:
All bacteria die
Growth rate equals death rate
Bacteria form spores only
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 become dormant
Time for population to double
Time to transfer DNA
Time to form spores

Explanation:

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

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

Explanation:

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

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

Explanation:

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

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

Explanation:

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

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

Explanation:

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

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

Explanation:

Obligate anaerobes cannot survive in the presence of oxygen.

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

Explanation:

Facultative anaerobes can grow with or without oxygen.

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

Explanation:

Aerobic respiration uses oxygen as the final electron acceptor.

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

Explanation:

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

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

Explanation:

Lactobacillus and Streptococcus species ferment milk into yogurt.

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

Explanation:

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

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

Explanation:

Rhizobium forms nodules on legume roots for nitrogen fixation.

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

Explanation:

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

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

Explanation:

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

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

Explanation:

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

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

Explanation:

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

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

Explanation:

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

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

Explanation:

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

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

Explanation:

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

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

Explanation:

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

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