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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
Become dormant
Reproduce asexually

Explanation:

Binary fission is asexual reproduction producing two identical daughter cells.

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

Explanation:

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

Q. During which phase do bacteria grow fastest?
Lag phase
Death 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
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
Bacteria form spores only
All bacteria die
Growth rate equals death rate

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:
Neutral pH
Body temperature
Cold temperatures (<15°C)
High temperatures (>60°C)

Explanation:

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

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

Explanation:

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

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

Explanation:

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

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

Explanation:

Obligate anaerobes cannot survive in the presence of oxygen.

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

Explanation:

Facultative anaerobes can grow with or without oxygen.

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

Explanation:

Aerobic respiration uses oxygen as the final electron acceptor.

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

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
Clostridium and Bacillus
Lactobacillus and Streptococcus
Mycobacterium and Corynebacterium

Explanation:

Lactobacillus and Streptococcus species ferment milk into yogurt.

Q. Nitrogen-fixing bacteria convert:
Nitrate to N2
N2 to ammonia
N2 to nitrate
Ammonia 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
Human skin
Fish gills

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:
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
UV light
Filtration

Explanation:

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

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

Explanation:

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

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

Explanation:

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

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