Question 1

Which of the following statements best explains why Mycoplasma species are resistant to beta-lactam antibiotics such as amoxicillin?

Accepted Answer

They lack a cell wall and instead have a plasma membrane containing sterols.

Question 2

A scientist isolates a prokaryote with a cell wall composed of pseudomurein. Which of the following is most likely true about this organism?

Accepted Answer

It is a member of the Archaea domain.

Question 3

Which of the following best describes the function of bacterial capsules and slime layers?

Accepted Answer

They protect against desiccation and help evade host immune responses.

Question 4

A Gram-negative bacterium is found to have a periplasmic space. Which of the following best describes the location and function of this space?

Accepted Answer

It is located between the cytoplasmic membrane and the outer membrane, containing enzymes and transport proteins.

Question 5

Which of the following cell inclusions allows certain aquatic bacteria to orient themselves within Earth's magnetic field?

Accepted Answer

Magnetosomes

Question 6

A researcher is developing biodegradable plastics using bacteria. Which cell inclusion is most relevant to this process?

Accepted Answer

Polyhydroxyalkanoates (PHA)

Question 7

Fimbriae and pili are both protein structures on bacterial surfaces. Which of the following correctly distinguishes their primary functions?

Accepted Answer

Fimbriae are mainly for surface attachment, while pili can mediate genetic exchange and twitching motility.

Question 8

Which of the following best describes the mechanism by which bacterial flagella rotate?

Accepted Answer

The flow of protons ($H^+$) down their electrochemical gradient through the Mot proteins generates torque for rotation.

Question 9

A peritrichously flagellated bacterium is observed under a microscope. Which of the following best describes its movement pattern?

Accepted Answer

It alternates between runs (straight movement) and tumbles (reorientation).

Question 10

Which of the following is NOT a type of taxis observed in bacteria?

Accepted Answer

Thermotaxis

Question 11

During chemotaxis, how do bacteria sense and respond to chemical gradients?

Accepted Answer

They use chemoreceptors to detect attractants or repellents and adjust their run and tumble behavior accordingly.

Question 12

Which of the following statements about endospores is correct?

Accepted Answer

Endospores are highly resistant to heat, chemicals, and radiation, allowing survival in harsh environments.

Question 13

A patient is diagnosed with walking pneumonia caused by Mycoplasma pneumoniae. Which structural feature of this bacterium is most relevant to its pathogenicity and antibiotic resistance?

Accepted Answer

Lack of a cell wall and presence of sterols in the plasma membrane

Question 14

Which of the following best explains why Bacillus anthracis endospores are a concern for public health and bioterrorism?

Accepted Answer

They can remain dormant and viable for many years, resisting harsh conditions.

Question 15

A bacterium is found to accumulate large amounts of polyphosphate granules. What is the most likely function of these inclusions?

Accepted Answer

Storage of inorganic phosphate for future use in nucleic acid and phospholipid synthesis

Question 16

Which of the following best describes the difference between a capsule and a slime layer in bacteria?

Accepted Answer

Capsules are tightly bound and organized, while slime layers are loosely attached and unorganized.

Question 17

A researcher observes a bacterium that moves rapidly in a corkscrew fashion. Which structure is most likely responsible for this type of motility?

Accepted Answer

Periplasmic (axial) flagella

Question 18

Which of the following is a correct sequence of events during the bacterial endospore formation process?

Accepted Answer

Vegetative cell → Sporulation → Endospore → Germination

Question 19

A bacterium is found to have gas vesicles. What is the primary function of these structures?

Accepted Answer

Confer buoyancy to allow the cell to position itself in the water column

Question 20

Which of the following best explains why penicillin is ineffective against most Archaea?

Accepted Answer

Archaea lack peptidoglycan and instead have cell walls made of pseudomurein or other polymers.

Microbial Cell Structure and Function: Study Notes for Microbiology 300

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