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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
Form spores
Reproduce asexually
Become dormant

Explanation:

Binary fission is asexual reproduction producing two identical daughter cells.

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

Explanation:

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

Q. During which phase do bacteria grow fastest?
Death phase
Lag 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:
Adapt without dividing
Divide rapidly
Die
Form spores

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
Growth rate equals death rate
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 transfer DNA
Time to become dormant
Time for population to double
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:
Psychrophiles
Thermophiles
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)
Neutral pH
Body temperature
Cold temperatures (<15°C)

Explanation:

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

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

Explanation:

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

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

Explanation:

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

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

Explanation:

Obligate anaerobes cannot survive in the presence of oxygen.

Q. Facultative anaerobes:
Are killed by oxygen
Require 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
Photosynthesis
Fermentation
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?
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:
Ammonia to N2
N2 to ammonia
N2 to nitrate
Nitrate to N2

Explanation:

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

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

Explanation:

Rhizobium forms nodules on legume roots for nitrogen fixation.

Q. Which is a selective medium for Gram-negative bacteria?
MacConkey agar
Chocolate 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
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?
Dry heat
High-pressure steam
Filtration
UV light

Explanation:

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

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

Explanation:

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

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

Explanation:

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

Q. CFU stands for:
Culture Fast Unit
Cellular Function 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:
Total bacteria including dead
Bacterial DNA
Living bacteria
Bacterial proteins

Explanation:

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

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

Explanation:

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

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