Question 1

Which of the following best describes the difference between prokaryotic and eukaryotic cells?

Accepted Answer

Eukaryotic cells have a nucleus, while prokaryotic cells lack a nucleus.

Question 2

A microbiologist wants to count the number of viable E. coli cells in a food sample. Which method should they use for the most accurate result?

Accepted Answer

Viable plate count (spread plate or pour plate)

Question 3

Which of the following statements about the Gram stain is correct?

Accepted Answer

Gram-positive bacteria have a thick peptidoglycan layer that retains the crystal violet stain.

Question 4

Which formula is used to calculate the number of generations ($$n) in a $$bacterial culture, given initial cell number $$N_0$$ and final cell number $$N$$?

Accepted Answer

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

Question 5

Which adaptation allows psychrophilic microorganisms to thrive in cold environments?

Accepted Answer

Cytoplasmic membranes with high levels of unsaturated fatty acids

Question 6

A bacterial culture is growing in a batch system. After a period of rapid growth, nutrients become limited and cell division slows. Which phase of the growth curve is the culture entering?

Accepted Answer

Stationary phase

Question 7

Which of the following is a function of the cytoplasmic membrane in bacteria?

Accepted Answer

Acts as a selective permeability barrier

Question 8

Why are colony-forming units (CFUs) used instead of direct cell counts in plate count methods?

Accepted Answer

CFUs account for clumps of cells that form a single colony

Question 9

Which type of culture media contains ingredients of unknown chemical composition, such as yeast or meat extracts?

Accepted Answer

Complex media

Question 10

A scientist is using a spectrophotometer to measure the turbidity of a bacterial culture. What does an increase in optical density (OD) indicate?

Accepted Answer

An increase in the number of cells

Question 11

Which of the following best describes the function of pili in bacteria?

Accepted Answer

Gliding/twitching motility and genetic exchange

Question 12

Which of the following is NOT a property shared by all cells?

Accepted Answer

Presence of peptidoglycan in the cell wall

Question 13

Which of the following statements about endospores is correct?

Accepted Answer

Endospores are highly resistant structures formed by certain bacteria for survival under harsh conditions.

Question 14

Which of the following is a major component of the outer membrane of Gram-negative bacteria?

Accepted Answer

Lipopolysaccharide (LPS)

Question 15

A microbiologist streaks a plate to isolate a pure culture. What is the main purpose of this technique?

Accepted Answer

To obtain colonies derived from a single microbe

Question 16

Which of the following best explains why selective media are used in microbiology?

Accepted Answer

To inhibit the growth of some organisms while allowing others to grow

Question 17

Which type of motility is powered by a proton-motive force in bacteria?

Accepted Answer

Flagellar swimming

Question 18

A bacterial cell divides by binary fission every 30 minutes. If you start with 1 cell, how many cells will there be after 3 hours? Use the formula $$N = N_0$ 	imes 2^n$$, where $$n is $$the number of generations.

Accepted Answer

64

Question 19

Which of the following is a reason why direct microscopic counts may overestimate the number of viable cells in a sample?

Accepted Answer

They count both living and dead cells.

Question 20

Which of the following best describes the role of cell inclusions such as glycogen and polyhydroxyalkanoates (PHA) in bacteria?

Accepted Answer

They serve as carbon and energy storage materials.

Microbial Growth, Culturing, and Cell Structure: Study Notes for Microbiology

Guida di studio - Domande di pratica

Study guide - Flashcard