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TestMaster MCQs

Bacterial Growth & Metabolism Questions

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

Explanation:

Binary fission is asexual reproduction producing two identical daughter cells.

Q. The bacterial growth curve has how many phases?
Three
Two
Four
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
Log (exponential) phase
Stationary 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
Die
Form spores
Divide rapidly

Explanation:

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

Q. In the stationary phase:
Bacteria divide fastest
Growth rate equals death rate
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 to become dormant
Time for population to double
Time to form spores
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:
Hyperthermophiles
Mesophiles
Thermophiles
Psychrophiles

Explanation:

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

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

Explanation:

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

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

Explanation:

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

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

Explanation:

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

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

Explanation:

Obligate anaerobes cannot survive in the presence of oxygen.

Q. Facultative anaerobes:
Require CO2
Require oxygen
Are killed by oxygen
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
Fermentation
Aerobic respiration
Photosynthesis

Explanation:

Aerobic respiration uses oxygen as the final electron acceptor.

Q. Fermentation in bacteria produces:
Only oxygen
ATP without oxygen
Only water
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?
Lactobacillus and Streptococcus
Mycobacterium and Corynebacterium
E. coli and Salmonella
Clostridium and Bacillus

Explanation:

Lactobacillus and Streptococcus species ferment milk into yogurt.

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

Explanation:

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

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

Explanation:

Rhizobium forms nodules on legume roots for nitrogen fixation.

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

Explanation:

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

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

Explanation:

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

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

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 virus
A single cell
Multiple cells
A spore

Explanation:

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

Q. CFU stands for:
Cellular Function Unit
Culture Fast Unit
Cell Fusion Unit
Colony-Forming 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:
Binary fission only
Horizontal gene transfer
Spore formation
Capsule formation

Explanation:

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

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