Question 1

Which of the following best describes binary fission in bacteria?

Accepted Answer

A process where a single cell divides into two genetically identical daughter cells after replicating its chromosome.

Question 2

Which protein is primarily responsible for forming the Z-ring during bacterial cytokinesis?

Accepted Answer

FtsZ

Question 3

A rod-shaped bacterium is found to lose its characteristic shape and become spherical. Which cytoskeletal protein is most likely depleted?

Accepted Answer

MreB

Question 4

Which of the following equations correctly calculates the number of cells after n generations, starting from an initial population $$N_0$$?

Accepted Answer

$$N_t = N_0$ 	imes 2^n$$

Question 5

A bacterial culture starts with 100 cells and reaches 12,800 cells after 7 generations. What is the generation time if this occurs over 210 minutes?

Accepted Answer

$$g = \frac{210}{7} = 30$$ minutes/generation

Question 6

Which phase of the microbial growth curve is characterized by a balance between cell division and cell death?

Accepted Answer

Stationary phase

Question 7

Which adaptation allows extreme halophiles to survive in high-salt environments?

Accepted Answer

Accumulation of K+ and Cl- ions in the cytoplasm

Question 8

Which of the following best describes the function of superoxide dismutase (SOD) in aerobic bacteria?

Accepted Answer

It converts superoxide radicals to hydrogen peroxide, protecting cells from reactive oxygen species.

Question 9

Which type of culture medium contains ingredients of unknown chemical composition and is used to support the growth of many microorganisms?

Accepted Answer

Complex medium

Question 10

A microbiologist wants to isolate a Gram-negative, lactose-fermenting bacterium from a mixed sample. Which medium should they use?

Accepted Answer

MacConkey agar

Question 11

Which of the following is a direct method for measuring microbial population size?

Accepted Answer

Counting chambers (hemocytometer)

Question 12

Which environmental factor is most likely to limit the growth of a mesophile in a hot spring (90°C)?

Accepted Answer

Temperature

Question 13

Which of the following best describes quorum sensing in bacteria?

Accepted Answer

A process where bacteria communicate using small signaling molecules to coordinate gene expression based on population density.

Question 14

Which of the following is true about biofilms?

Accepted Answer

Biofilms protect microbes from harmful agents and can lead to antibiotic resistance.

Question 15

Which equation would you use to calculate the number of generations ($$n) if $$you know the initial ($$N_0) $$and final ($$N_t) $$cell numbers?

Accepted Answer

$$n = \frac{\log_{10} N_t - \log_{10} N_0$}{\log_{10} 2}$$

Question 16

Which of the following best describes the function of the Min system in E. coli cell division?

Accepted Answer

It prevents FtsZ polymerization at the cell poles, ensuring Z-ring formation at midcell.

Question 17

Which of the following is a characteristic of obligate anaerobes?

Accepted Answer

They are usually killed in the presence of oxygen.

Question 18

A culture medium that allows only Gram-negative bacteria to grow and distinguishes lactose fermenters by a color change is best described as:

Accepted Answer

Selective and differential

Question 19

Which of the following adaptations is NOT typically found in thermophiles?

Accepted Answer

Increased unsaturated fatty acids in membranes

Question 20

Which of the following best explains why plate count results are expressed as colony forming units (CFUs) rather than cells?

Accepted Answer

A colony may arise from a single cell or a group of cells, so CFU reflects viable units rather than individual cells.

Bacterial and Archaeal Growth: Mechanisms, Environmental Factors, and Laboratory Cultivation

Study Guide - Practice Questions