Question 1

Which of the following best explains why Gram-negative bacteria are generally more resistant to antibiotics that target peptidoglycan synthesis than Gram-positive bacteria?

Accepted Answer

Gram-negative bacteria possess an outer membrane that acts as a barrier to many antibiotics.

Question 2

A bacterium is observed to have a single flagellum at each end of its cell. What is the correct term for this flagellar arrangement?

Accepted Answer

Amphitrichous

Question 3

Which of the following statements about the bacterial capsule is CORRECT?

Accepted Answer

It is a well-organized, gelatinous layer that can protect bacteria from phagocytosis.

Question 4

Which component of the Gram-negative bacterial cell envelope is responsible for the toxic effects seen in septic shock?

Accepted Answer

Lipid A of lipopolysaccharide (LPS)

Question 5

A scientist isolates a microorganism with a plasma membrane containing ether-linked lipids and tetra-ether glycerol. Which group does this organism most likely belong to?

Accepted Answer

Archaea

Question 6

Which of the following best describes the function of the bacterial cell wall?

Accepted Answer

It provides structural support and protects against osmotic lysis.

Question 7

A patient is infected with a bacterium that lacks peptidoglycan in its cell wall. Which of the following is most likely TRUE about this organism?

Accepted Answer

It is resistant to antibiotics that target peptidoglycan synthesis.

Question 8

Which of the following transport mechanisms across the bacterial plasma membrane requires energy input from ATP hydrolysis?

Accepted Answer

Active transport via ABC transporters

Question 9

During a Gram stain, a bacterium retains the crystal violet dye and appears purple under the microscope. Which structural feature is most responsible for this result?

Accepted Answer

A thick peptidoglycan layer

Question 10

Which of the following best explains why bacterial endospores are highly resistant to heat and chemicals?

Accepted Answer

They contain dipicolinic acid and small acid-soluble proteins that protect DNA.

Question 11

A bacterium is placed in a hypertonic solution. What process will most likely occur, and what is the expected outcome?

Accepted Answer

Plasmolysis; the cell will shrink as water leaves.

Question 12

Which of the following is a function of the glycocalyx in bacteria?

Accepted Answer

Protection from desiccation and adherence to surfaces

Question 13

Which of the following best describes the difference between facilitated diffusion and active transport in bacteria?

Accepted Answer

Facilitated diffusion uses channel or carrier proteins without energy input, while active transport requires energy to move substances against a gradient.

Question 14

Which of the following is a unique feature of archaeal cell membranes compared to bacterial cell membranes?

Accepted Answer

Ether-linked isoprenoid lipids

Question 15

A researcher observes a bacterium with flagella distributed all over its surface. What is the correct term for this arrangement, and what is its advantage?

Accepted Answer

Peritrichous; allows movement in multiple directions and efficient chemotaxis

Question 16

Which of the following statements about peptidoglycan is TRUE?

Accepted Answer

It consists of repeating units of N-acetylglucosamine and N-acetylmuramic acid cross-linked by short peptides.

Question 17

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

Accepted Answer

They provide rigidity to the cell wall and play a role in ion transport.

Question 18

A bacterial cell is exposed to lysozyme. Which of the following best describes the effect of lysozyme on the cell wall?

Accepted Answer

Lysozyme hydrolyzes the glycosidic bonds between N-acetylglucosamine and N-acetylmuramic acid in peptidoglycan.

Question 19

Which of the following best explains why mycoplasma species are resistant to antibiotics such as penicillin?

Accepted Answer

They lack a cell wall and therefore lack peptidoglycan.

Question 20

A bacterium is placed in a solution containing a high concentration of glucose. The bacterium uses a phosphotransferase system (PTS) to transport glucose into the cell. Which of the following best describes this process?

Accepted Answer

Glucose is transported via group translocation, where it is phosphorylated during transport.

Prokaryotic and Eukaryotic Cell Structures and Functions: Microbiology Study Notes

Guida di studio - Domande di pratica

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