Question 1

Which of the following best explains why Gram-negative bacteria are generally more resistant to antibiotics such as penicillin than Gram-positive bacteria?

Accepted Answer

Their outer membrane acts as an impermeable barrier to many chemicals, including antibiotics.

Question 2

A patient is diagnosed with pneumonia caused by Streptococcus pneumoniae. The strain is found to lack a capsule. Which of the following is the most likely consequence?

Accepted Answer

The bacterium will be less able to resist phagocytosis and thus less likely to cause disease.

Question 3

Which of the following structures is primarily responsible for the transfer of genetic material between bacterial cells during conjugation?

Accepted Answer

F pilus

Question 4

A scientist is studying a bacterium with a cell wall composed of multiple layers of peptidoglycan and teichoic acid, but lacking an outer membrane. Which type of bacterium is this most likely to be?

Accepted Answer

Gram-positive

Question 5

Which of the following best describes the chemical bond linking N-acetyl Muramic acid (NAM) and N-acetyl Glucosamine (NAG) in bacterial peptidoglycan?

Accepted Answer

β 1-4 glycosidic bond

Question 6

Which of the following is a function of the bacterial capsule (glycocalyx)?

Accepted Answer

Protection against phagocytosis

Question 7

A laboratory technician is using a Shaeffer-Fulton stain. What structure is she most likely trying to visualize?

Accepted Answer

Endospores

Question 8

Which of the following statements about bacterial ribosomes is correct?

Accepted Answer

They are the site of protein synthesis and are targeted by some antibiotics.

Question 9

Which of the following best explains why Mycoplasma species are unaffected by penicillin?

Accepted Answer

They lack a cell wall, so penicillin has no target to attack.

Question 10

A bacterium is found to have magnetosomes. What is the most likely function of these structures?

Accepted Answer

Orientation in response to gravity or magnetic fields

Question 11

Which of the following is a correct description of the function of porins in Gram-negative bacteria?

Accepted Answer

They serve as channels for the transport of small molecules across the outer membrane.

Question 12

Which of the following best describes the role of dipicolinic acid (DPA) in bacterial endospores?

Accepted Answer

It contributes to the heat resistance of endospores.

Question 13

A researcher is studying a bacterium that forms a pellicle in broth culture and is highly adherent to surfaces. Which structure is most likely responsible for these properties?

Accepted Answer

Common pili (fimbriae)

Question 14

Which of the following is NOT a function of the bacterial cell wall?

Accepted Answer

Regulation of molecular traffic into and out of the cell

Question 15

Which of the following best explains why lysozyme is effective against many bacteria?

Accepted Answer

It breaks the $$\beta\ 1-4$$ glycosidic bonds between NAM and NAG in peptidoglycan.

Question 16

A Gram-negative bacterium is exposed to an antibiotic that targets peptidal bridges in peptidoglycan. Which of the following best predicts the outcome?

Accepted Answer

The bacterium may be affected, but less so than a Gram-positive bacterium due to its thinner peptidoglycan layer and protective outer membrane.

Question 17

Which of the following is a unique feature of the nucleoid in prokaryotic cells?

Accepted Answer

It contains a single, circular, double-stranded DNA molecule.

Question 18

A patient is infected with a bacterium that is able to survive boiling for 8-10 hours. Which structure is most likely responsible for this resistance?

Accepted Answer

Endospore

Question 19

Which of the following best describes the arrangement of phospholipids and proteins in the bacterial cell membrane according to the fluid-mosaic model?

Accepted Answer

A bilayer of phospholipids with embedded integral and peripheral proteins

Question 20

Which of the following is a correct match between a bacterial genus and a characteristic inclusion or structure it possesses?

Accepted Answer

Clostridium – metachromatic (volutin) granules

Bacterial Cell Structure: An Overview

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