Chapter 4

Multiple Choice Test:

1. Describe binary fission and how it relates to exponential growth.

a. Asexual reproduction method in bacteria; exponential growth occurs when cells divide at a constant rate.

b. Sexual reproduction method in bacteria; exponential growth occurs when cells merge and replicate.

c. Asexual reproduction method in humans; exponential growth occurs during mitosis.

d. Sexual reproduction method in humans; exponential growth occurs during meiosis.

Answer: a

2. Calculate the number of cells in a culture if given the original number of cells, the time it takes for a cell to replicate, and the length of incubation.

a. N = N0 * 2^(t/d)

b. N = N0 * t/d

c. N = N0 + (t/d)

d. N = N0 - (t/d)

Answer: a

3. Describe a biofilm and why they are important to humans – beneficial, harmful, or neutral.

a. A thin layer of dead cells; harmful to humans causing infections.

b. A colony of bacteria on a surface; beneficial for medical implants.

c. A slimy layer of bacteria adhered to a surface; can be beneficial or harmful to humans.

d. A protective layer of viruses; neutral to humans.

Answer: c

4. Describe the stages of a growth curve. If given graphical data, determine the location of the phases of growth for a given bacterial culture.

a. Lag phase, Log/exponential phase, Stationary phase, Death phase.

b. Exponential phase, Lag phase, Stationary phase, Death phase.

c. Log phase, Death phase, Lag phase, Stationary phase.

d. Stationary phase, Log phase, Lag phase, Death phase.

Answer: a

5. Describe what occurs in each bacterial growth phase based on the following:

a. Rate of cell division is equal to the rate of cell death.

b. Cell numbers – increasing, decreasing, or staying the same.

c. Most sensitive to antibiotics.

d. Logarithmic decrease in cell number.

e. Survival of the fittest during this phase.

Answer: a - Log/exponential phase; b - Log/exponential phase; c - Log/exponential phase; d - Death phase; e - Stationary phase

7. Describe how different conditions affect bacterial cell growth.

a. pH, temperature, nutrient availability, and oxygen.

b. Light, sound, humidity, and pressure.

c. Social interactions, time of day, color of surroundings, and atmospheric composition.

d. Gravity, magnetic fields, air pollution, and season.

Answer: a

8. Classify the following categories of bacteria based on temperature preference and their location in nature.

a. Psychrophiles

b. Mesophiles

c. Thermophiles

d. Psychotrophs

e. Hyperthermophiles

Answer: a - Cold environments; b - Moderate environments; c - Hot environments; d - Moderate environments; e - Extremely hot environments

9. Classify the following categories of bacteria based on oxygen preference and if they use aerobic respiration, anaerobic respiration, and/or fermentation. Identify their location in a tube of medium.

a. Obligate aerobes

b. Microaerophiles

c. Obligate anaerobes

d. Aerotolerant anaerobes

e. Facultative anaerobes

Answer: a - Top of the tube; b - Middle of the tube; c - Bottom of the tube; d - Evenly distributed in the tube; e - Throughout the tube

10. Classify the following categories of bacteria based on their carbon and energy sources:

a. Photoautotrophs

b. Photoheterotrophs

c. Chemolithoautotrophs

d. Chemoorganoheterotrophs

Answer: a - Light and CO2; b - Light and organic compounds; c - Inorganic compounds and CO2; d - Organic compounds

How did you do?