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TestMaster MCQs

Bacterial Growth & Metabolism Questions

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

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?
Lag phase
Death phase
Stationary phase
Log (exponential) phase

Explanation:

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

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

Explanation:

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

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

Explanation:

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

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

Explanation:

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

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

Explanation:

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

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

Explanation:

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

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

Explanation:

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

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

Explanation:

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

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

Explanation:

Obligate anaerobes cannot survive in the presence of oxygen.

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

Explanation:

Facultative anaerobes can grow with or without oxygen.

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

Explanation:

Aerobic respiration uses oxygen as the final electron acceptor.

Q. Fermentation in bacteria produces:
ATP without oxygen
Only glucose
Only 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
Lactobacillus and Streptococcus
Mycobacterium and Corynebacterium
Clostridium and Bacillus

Explanation:

Lactobacillus and Streptococcus species ferment milk into yogurt.

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

Explanation:

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

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

Explanation:

Rhizobium forms nodules on legume roots for nitrogen fixation.

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

Explanation:

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

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

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:
Controlled heating to kill pathogens
High-pressure steam
Radiation
UV light

Explanation:

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

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

Explanation:

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

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

Explanation:

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

Q. Viable plate count measures:
Total bacteria including dead
Bacterial proteins
Living bacteria
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
Spore formation
Capsule formation

Explanation:

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

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