Question 1

Which of the following statements best explains why penicillin is effective against bacteria but not against human cells?

Accepted Answer

Penicillin targets the peptidoglycan found in bacterial cell walls, which human cells lack.

Question 2

A bacterial cell is placed in a hypertonic solution. What is the most likely outcome for the cell?

Accepted Answer

The cell will undergo plasmolysis as water leaves the cell.

Question 3

Which of the following formulas correctly calculates the number of generations ($$n) in a $$bacterial population given the initial ($$N_0) $$and final ($$N_t) $$cell counts?

Accepted Answer

$$n = \frac{\log N_t - \log N_0$}{0.301}$$

Question 4

Which structure is responsible for motility in bacteria and is composed of the protein flagellin?

Accepted Answer

Flagella

Question 5

A Gram-negative bacterium is exposed to lysozyme. What is the most likely effect?

Accepted Answer

Lysozyme breaks glycosidic bonds in the peptidoglycan, weakening the cell wall.

Question 6

Which of the following is a correct description of the bacterial population growth equation?

Accepted Answer

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

Question 7

A patient with cystic fibrosis is suffering from a persistent lung infection. Which microbial phenomenon is most likely contributing to the difficulty in treating this infection?

Accepted Answer

Biofilm formation by bacteria, which protects them from antibiotics and the immune system.

Question 8

Which of the following is NOT a function of the bacterial plasma membrane?

Accepted Answer

Synthesis of peptidoglycan for the cell wall.

Question 9

A bacterium is placed in a hypotonic environment after being treated with penicillin. What is the most likely outcome?

Accepted Answer

The cell will burst (lysis) due to water influx and weakened cell wall.

Question 10

Which of the following is a distinguishing feature of Archaea compared to Bacteria?

Accepted Answer

Archaea lack peptidoglycan in their cell walls.

Question 11

Which environmental factor is most likely to affect the growth of barophiles?

Accepted Answer

Pressure

Question 12

A bacterial culture starts with 100 cells and grows to 800 cells after 3 generations. Which formula would you use to confirm this population growth?

Accepted Answer

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

Question 13

Which of the following best describes the function of teichoic acids in Gram-positive bacteria?

Accepted Answer

They help maintain cell wall structure and regulate ion movement.

Question 14

Which enzyme is responsible for detoxifying hydrogen peroxide in bacteria?

Accepted Answer

Catalase

Question 15

Which of the following is a correct description of group translocation in bacteria?

Accepted Answer

A substance is chemically altered during transport across the membrane.

Question 16

Which bacterial structure is most important for attachment to surfaces and formation of biofilms?

Accepted Answer

Fimbriae

Question 17

A bacterial cell is observed to have a thick peptidoglycan layer and teichoic acids. What is its Gram reaction?

Accepted Answer

Gram positive

Question 18

Which of the following equations would you use to calculate generation time ($$g) if $$you know the total time ($$t) $$and the number of generations ($$n$$)?

Accepted Answer

$$g = \frac{t}{n}$$

Question 19

Which of the following is NOT a characteristic of viruses?

Accepted Answer

They reproduce by binary fission.

Question 20

Which bacterial structure is most likely to be found in spirochetes and is responsible for their corkscrew motion?

Accepted Answer

Axial filaments

Introduction to Microbiology: Microbial World, Cell Structure, and Growth

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