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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
Form spores
Reproduce asexually

Explanation:

Binary fission is asexual reproduction producing two identical daughter cells.

Q. The bacterial growth curve has how many phases?
Three
Four
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
Log (exponential) phase
Lag phase
Death phase

Explanation:

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

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

Explanation:

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

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

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
Mesophiles
Psychrophiles
Hyperthermophiles

Explanation:

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

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

Explanation:

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

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

Explanation:

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

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

Explanation:

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

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

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:
Fermentation
Aerobic respiration
Anaerobic respiration
Photosynthesis

Explanation:

Aerobic respiration uses oxygen as the final electron acceptor.

Q. Fermentation in bacteria produces:
Only oxygen
Only glucose
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?
Mycobacterium and Corynebacterium
Clostridium and Bacillus
E. coli and Salmonella
Lactobacillus and Streptococcus

Explanation:

Lactobacillus and Streptococcus species ferment milk into yogurt.

Q. Nitrogen-fixing bacteria convert:
N2 to ammonia
N2 to nitrate
Nitrate to N2
Ammonia 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
Legume roots
Animal intestines

Explanation:

Rhizobium forms nodules on legume roots for nitrogen fixation.

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

Explanation:

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

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

Explanation:

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

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

Explanation:

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

Q. Pasteurization uses:
UV light
High-pressure steam
Radiation
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 single cell
A virus

Explanation:

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

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

Explanation:

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

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