Question 1

Which of the following best describes the structure and function of the bacterial plasma membrane?

Accepted Answer

It is a phospholipid bilayer with embedded proteins that controls the movement of substances in and out of the cell.

Question 2

A microbiologist observes a group of spherical bacteria arranged in chains under the microscope. What is the correct term for this arrangement?

Accepted Answer

Streptococcus

Question 3

Which of the following statements about Gram-negative bacteria is correct?

Accepted Answer

Their outer membrane contains lipopolysaccharide (LPS), which can act as an endotoxin.

Question 4

A bacterial cell is observed to have a flexible spiral shape and moves using axial filaments located in the periplasmic space. What is the most likely classification of this bacterium?

Accepted Answer

Spirochete

Question 5

Which of the following best explains why agar is preferred over gelatin as a solidifying agent in microbiological media?

Accepted Answer

Agar is not degraded by most bacteria and has a higher melting point than gelatin.

Question 6

A researcher is studying a bacterial protein that spans the plasma membrane and allows sodium ions to move from high to low concentration without using energy. Which type of transport is being described?

Accepted Answer

Facilitated diffusion (passive transport)

Question 7

Which of the following is a function of the bacterial glycocalyx when present as a capsule?

Accepted Answer

It helps the cell resist desiccation and evade the host immune system.

Question 8

A bacterial cell is able to move toward a chemical attractant in its environment. What is the term for this type of movement, and what structure is primarily responsible?

Accepted Answer

Chemotaxis; flagellum

Question 9

Which of the following best describes the process of autoclaving for sterilization?

Accepted Answer

Injecting steam at $$121^\circC $$and 15 psi for about 15 minutes to kill all microbes, including endospores.

Question 10

Which of the following is a correct statement about bacterial ribosomes?

Accepted Answer

They are 70S and are responsible for protein synthesis.

Question 11

A scientist is preparing a synthetic minimal medium for bacterial growth. Which of the following best describes this type of medium?

Accepted Answer

It contains only the exact nutrients required for growth, with all ingredients known.

Question 12

Which of the following structures is directly involved in bacterial conjugation (DNA transfer between cells)?

Accepted Answer

F pilus

Question 13

A bacterial cell is observed to have a thick, tightly organized sugar layer outside its cell wall. Which term best describes this structure, and what is one of its main functions?

Accepted Answer

Capsule; helps evade the host immune system

Question 14

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

Accepted Answer

Their outer membrane acts as a barrier to many antibiotics.

Question 15

A student is using sterile technique to inoculate a plate. Which of the following steps is most critical to prevent contamination?

Accepted Answer

Disinfecting the workspace and sterilizing instruments before use.

Question 16

Which of the following correctly matches a bacterial shape with its description?

Accepted Answer

Spirillum: rigid corkscrew-shaped

Question 17

A bacterial cell is observed to have a network of protein fibers that help maintain its shape. What is this structure called?

Accepted Answer

Cytoskeleton

Question 18

Which of the following best describes the function of the S layer in some bacteria?

Accepted Answer

It is a protein layer that helps the cell stick to surfaces.

Question 19

A bacterial cell is exposed to a new antibiotic that targets the synthesis of tetrapeptides. Which cell structure will be most directly affected?

Accepted Answer

Peptidoglycan cell wall

Question 20

Which of the following best describes the process of diffusion as it occurs in bacterial cells?

Accepted Answer

Molecules move from high to low concentration due to random Brownian motion.

Functional Anatomy of Prokaryotic and Eukaryotic Cells & Microbial Growth Media

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