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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
Form spores
Transfer DNA
Reproduce asexually

Explanation:

Binary fission is asexual reproduction producing two identical daughter cells.

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

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
Lag phase
Death phase
Stationary phase

Explanation:

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

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

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 become dormant
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:
Psychrophiles
Mesophiles
Hyperthermophiles
Thermophiles

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

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:
Obligate anaerobes
Aerotolerant anaerobes
Obligate aerobes
Facultative anaerobes

Explanation:

Obligate anaerobes cannot survive in the presence of oxygen.

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

Explanation:

Facultative anaerobes can grow with or without oxygen.

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

Explanation:

Aerobic respiration uses oxygen as the final electron acceptor.

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

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 nitrate
Ammonia to N2
Nitrate to N2
N2 to ammonia

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?
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?
Dry heat
UV light
Filtration
High-pressure steam

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:
Colony-Forming Unit
Cellular Function Unit
Cell Fusion Unit
Culture Fast Unit

Explanation:

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

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

Explanation:

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

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

Explanation:

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

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