Question 1

Which structural feature distinguishes Gram-positive bacteria from Gram-negative bacteria during a Gram stain procedure?

Accepted Answer

Thick peptidoglycan layer in the cell wall

Question 2

A microbiologist observes a bacterium with a rod-shaped morphology under the microscope. Which term best describes this bacterium?

Accepted Answer

Bacillus

Question 3

Which of the following statements about Archaea is correct?

Accepted Answer

They have unique membrane lipids not found in Bacteria.

Question 4

A patient is treated with penicillin for a bacterial infection. Which cellular process is directly inhibited by this antibiotic?

Accepted Answer

Transpeptidation of peptidoglycan cross-links

Question 5

During a laboratory experiment, a bacterial culture is exposed to an antibiotic. The minimum concentration that prevents visible growth is determined. Which term best describes this value?

Accepted Answer

MIC (Minimum Inhibitory Concentration)

Question 6

Which equation correctly represents the calculation of generation time ($g$) given the initial population ($N_0$), final population ($N$), and elapsed time ($t$) during the log phase of bacterial growth?

Accepted Answer

$g = \frac{t}{\log_2(N/N_0)}$

Question 7

A bacterium is found thriving in a hot spring at 90°C. Which classification best describes this organism?

Accepted Answer

Hyperthermophile

Question 8

Which component of the Gram-negative bacterial cell envelope acts as an endotoxin and can trigger a strong immune response in humans?

Accepted Answer

Lipopolysaccharide (LPS)

Question 9

A microbiologist is studying a surface-attached microbial community that is resistant to antibiotics and immune responses. What is the term for this structure?

Accepted Answer

Biofilm

Question 10

Which of the following best describes a facultative anaerobe?

Accepted Answer

Can grow with or without oxygen

Question 11

Which process is targeted by vancomycin, leading to inhibition of bacterial cell wall synthesis?

Accepted Answer

Binding to D-Ala-D-Ala residues

Question 12

A scientist is investigating horizontal gene transfer in bacteria. Which scenario best illustrates this process?

Accepted Answer

A bacterium acquires DNA from another organism, leading to new traits.

Question 13

Which of the following is a correct description of a prokaryotic cell?

Accepted Answer

Lacks a nucleus and membrane-bound organelles

Question 14

A bacterium is observed to have a protective polysaccharide coating that enhances its resistance to phagocytosis. What is this structure called?

Accepted Answer

Capsule (Glycocalyx)

Question 15

Which of the following best describes the function of the cell wall in bacteria?

Accepted Answer

Prevents osmotic lysis

Question 16

A microbiologist is culturing bacteria in a high-salt environment. Which term best describes organisms that thrive under these conditions?

Accepted Answer

Halophile

Question 17

Which phase of the bacterial growth curve is characterized by rapid cell division and exponential increase in population?

Accepted Answer

Log phase

Question 18

A bacterial cell is described as unicellular. Which statement best explains this characteristic?

Accepted Answer

A single cell performs all life functions.

Question 19

Which of the following is a correct description of the phospholipid structure found in cell membranes?

Accepted Answer

Hydrophilic head and hydrophobic tails

Question 20

A bacterium is classified as a mesophile. Which temperature range would you expect it to grow best in?

Accepted Answer

$20^\circ \mathrm{C} - 45^\circ \mathrm{C}$

Essential Microbiology Terms and Concepts: Cell Structure, Growth, and Classification

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