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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
Reproduce asexually
Form spores
Transfer DNA

Explanation:

Binary fission is asexual reproduction producing two identical daughter cells.

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

Explanation:

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

Q. During which phase do bacteria grow fastest?
Log (exponential) phase
Death phase
Lag phase
Stationary phase

Explanation:

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

Q. In the lag phase, bacteria:
Die
Divide rapidly
Adapt without dividing
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 for population to double
Time to become dormant
Time to transfer DNA
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:
Mesophiles
Hyperthermophiles
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)
Neutral pH
High temperatures (>60°C)
Body temperature

Explanation:

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

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

Explanation:

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

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

Explanation:

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

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

Explanation:

Obligate anaerobes cannot survive in the presence of oxygen.

Q. Facultative anaerobes:
Grow with or without oxygen
Are killed by 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:
Photosynthesis
Anaerobic respiration
Fermentation
Aerobic respiration

Explanation:

Aerobic respiration uses oxygen as the final electron acceptor.

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

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:
Animal intestines
Fish gills
Legume roots
Human skin

Explanation:

Rhizobium forms nodules on legume roots for nitrogen fixation.

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

Explanation:

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

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

Explanation:

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

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

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
A spore
A single cell
Multiple cells

Explanation:

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

Q. CFU stands for:
Culture Fast Unit
Cell Fusion 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
Bacterial proteins
Living bacteria
Total bacteria including dead

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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