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TestMaster MCQs

Bacterial Growth & Metabolism Questions

Home Science Bacterial Growth & Metabolism
Q. Binary fission is the process by which bacteria:
Reproduce asexually
Become dormant
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
Five
Four
Three

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
Log (exponential) phase
Stationary phase

Explanation:

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

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

Explanation:

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

Q. In the stationary phase:
Bacteria form spores only
Growth rate equals death rate
Bacteria divide fastest
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 to transfer DNA
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
Hyperthermophiles
Thermophiles
Mesophiles

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:
Body temperature
Cold temperatures
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:
Microaerophiles
Obligate anaerobes
Facultative anaerobes
Obligate aerobes

Explanation:

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

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

Explanation:

Aerobic respiration uses oxygen as the final electron acceptor.

Q. Fermentation in bacteria produces:
Only oxygen
Only glucose
Only water
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?
Clostridium and Bacillus
Mycobacterium and Corynebacterium
Lactobacillus and Streptococcus
E. coli and Salmonella

Explanation:

Lactobacillus and Streptococcus species ferment milk into yogurt.

Q. Nitrogen-fixing bacteria convert:
N2 to ammonia
N2 to nitrate
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:
Legume roots
Fish gills
Human skin
Animal intestines

Explanation:

Rhizobium forms nodules on legume roots for nitrogen fixation.

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

Explanation:

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

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

Explanation:

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

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

Explanation:

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

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

Explanation:

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

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

Explanation:

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

Q. CFU stands for:
Colony-Forming Unit
Culture Fast Unit
Cellular Function Unit
Cell Fusion Unit

Explanation:

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

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

Explanation:

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

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

Explanation:

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

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