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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
Form spores
Reproduce asexually

Explanation:

Binary fission is asexual reproduction producing two identical daughter cells.

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

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:
All bacteria die
Growth rate equals death rate
Bacteria divide fastest
Bacteria form spores only

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 transfer DNA
Time to form spores
Time to become dormant

Explanation:

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

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

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:
High temperatures (45–80°C)
Cold temperatures
Low pH
Body temperature

Explanation:

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

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

Explanation:

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

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

Explanation:

Obligate anaerobes cannot survive in the presence of oxygen.

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

Explanation:

Facultative anaerobes can grow with or without oxygen.

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

Explanation:

Aerobic respiration uses oxygen as the final electron acceptor.

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

Explanation:

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

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

Explanation:

Lactobacillus and Streptococcus species ferment milk into yogurt.

Q. Nitrogen-fixing bacteria convert:
N2 to ammonia
Nitrate to N2
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
Animal intestines
Fish gills
Human skin

Explanation:

Rhizobium forms nodules on legume roots for nitrogen fixation.

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

Explanation:

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

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

Explanation:

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

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

Explanation:

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

Q. Pasteurization uses:
High-pressure steam
Radiation
UV light
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
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
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 DNA
Total bacteria including dead
Living bacteria
Bacterial proteins

Explanation:

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

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

Explanation:

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

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