identification and classification of microbes

Question 1

Which of the following best describes the shape of cocci bacteria?
A) Spiral-shaped
B) Rod-shaped
C) Spherical
D) Comma-shaped

Answer 1

C) Spherical

Question 2

What determines the arrangement of bacterial cells?
A) The presence of a cell wall
B) The plane of division and whether cells separate or not
C) The size of the bacterial cells
D) The thickness of the peptidoglycan layer

Answer 2

B) The plane of division and whether cells separate or not

Question 3

Which of the following terms refers to a pair of spherical bacterial cells that remain together after division?
A) Streptococci
B) Tetrads
C) Sarcina
D) Diplococci

Answer 3

D) Diplococci

Question 4

Staphylococci are characterized by their:
A) Chain-like arrangement
B) Random planes of division forming grape-like clusters
C) Formation of a cubic packet of eight cells
D) Spiral shape

Answer 4

B) Random planes of division forming grape-like clusters

Question 5

Which of the following is NOT a shape observed in bacteria?
A) Rods
B) Vibrios
C) Spirilla
D) Mycelium-like forms in archaea

Answer 5

D) Mycelium-like forms in archaea

Question 6

Which of the following describes a rigid spiral-shaped bacterium?
A) Spirilla
B) Spirochete
C) Coccobacilli
D) Vibrio

Answer 6

A) Spirilla

Question 7

Archaeal cells differ from bacterial cells in that archaea:
A) Have spirochete-like and mycelial forms
B) Lack spirochete-like or mycelial forms
C) Are all pleomorphic
D) Are always larger than bacterial cells

Answer 7

B) Lack spirochete-like or mycelial forms

Question 8

What is the primary role of the bacterial cell wall?
A) Protection against osmotic lysis
B) Energy production
C) Nutrient acquisition
D) DNA replication

Answer 8

A) Protection against osmotic lysis

Question 9

The Gram stain differentiates bacteria based on the:
A) Presence of flagella
B) Composition of the cell wall, particularly peptidoglycan
C) Shape of the bacterial cell
D) Size of the bacterial cell

Answer 9

B) Composition of the cell wall, particularly peptidoglycan

Question 10

Gram-negative bacteria are characterized by:
A) A thick peptidoglycan layer
B) A single plasma membrane
C) A thin peptidoglycan layer and an outer membrane
D) The presence of teichoic acids

Answer 10

C) A thin peptidoglycan layer and an outer membrane

Question 11

In a Gram-negative bacterial cell, the periplasmic space:
A) Is found between the plasma membrane and the outer membrane
B) Contains teichoic acids
C) Lacks hydrolytic enzymes
D) Is the site of peptidoglycan synthesis

Answer 11

A) Is found between the plasma membrane and the outer membrane

Question 12

Which part of the lipopolysaccharide (LPS) in Gram-negative bacteria helps in stabilizing the outer membrane?
A) O side chain
B) Core polysaccharide
C) Lipid A
D) Braun’s lipoprotein

Answer 12

C) Lipid A

Question 13

What is the function of the bacterial flagella?
A) Nutrient uptake
B) DNA replication
C) Movement
D) Cell wall synthesis

Answer 13

C) Movement

Question 14

Which of the following statements about bacterial flagella synthesis is true?
A) Flagellin molecules are added at the base of the flagella
B) The flagella are embedded entirely within the cytoplasm
C) Synthesis of flagella is not protein-dependent
D) Flagellin molecules self-assemble at the tip of the filament

Answer 14

D) Flagellin molecules self-assemble at the tip of the filament

Question 15

In a hypotonic environment, the bacterial cell wall:
A) Causes the cell to shrink
B) Prevents the cell from swelling and bursting
C) Acts as an impermeable barrier to water
D) Dissolves, allowing water to freely move across

Answer 15

B) Prevents the cell from swelling and bursting

Question 16

What are the two types of membrane proteins found in the bacterial plasma membrane?
A) Integral and peripheral membrane proteins
B) Structural and transport proteins
C) Peptidoglycan and lipid-based proteins
D) Glycoproteins and lipoproteins

Answer 16

A) Integral and peripheral membrane proteins

Question 17

Which of the following correctly describes amphipathic lipids in the bacterial plasma membrane?
A) Polar heads face inward, and hydrophobic tails face outward
B) Polar heads are hydrophobic, and tails are hydrophilic
C) Polar heads are hydrophilic, and hydrophobic tails face inward
D) Hydrophilic tails are embedded in the lipid bilayer

Answer 17

C) Polar heads are hydrophilic, and hydrophobic tails face inward

Question 18

Which of the following transport processes in bacteria is energy-dependent?
A) Passive diffusion
B) Facilitated diffusion
C) Active transport
D) Osmosis

Answer 18

C) Active transport

Question 19

Why is iron uptake important for bacterial cells?
A) Iron helps in nutrient transport
B) Iron is only needed for flagella synthesis
C) Iron is required for metabolic processes such as respiration
D) Iron stabilizes the cell wall structure

Answer 19

C) Iron is required for metabolic processes such as respiration

Question 20

Which component of the Gram-negative bacterial cell wall serves as an endotoxin?
A) Teichoic acid
B) Lipid A of lipopolysaccharide (LPS)
C) Peptidoglycan layer
D) O side chain of LPS

Answer 20

B) Lipid A of lipopolysaccharide (LPS)

Question 21

Which of the following statements about peptidoglycan structure is true?
A) It is a single long strand without cross-links
B) It is composed of alternating NAG and NAM sugars
C) It is present only in Gram-negative bacteria
D) It does not contain any amino acids

Answer 21

B) It is composed of alternating NAG and NAM sugars

Question 22

What role do teichoic acids play in Gram-positive bacteria?
A) They contribute to the negative charge of the outer membrane
B) They are involved in DNA replication
C) They help maintain the cell envelope and bind to host cells
D) They are responsible for flagella movement

Answer 22

C) They help maintain the cell envelope and bind to host cells

Question 23

What is the function of siderophores in bacterial cells?
A) Siderophores bind to and transport iron into the cell
B) Siderophores degrade the cell wall
C) Siderophores transport water across the membrane
D) Siderophores help bacteria in attaching to host cells

Answer 23

A) Siderophores bind to and transport iron into the cell

Question 24

In Gram-negative bacteria, Braun’s lipoproteins connect:
A) The outer membrane to the inner membrane
B) The outer membrane to peptidoglycan
C) The peptidoglycan layer to the plasma membrane
D) The lipopolysaccharide to the plasma membrane

Answer 24

B) The outer membrane to peptidoglycan

Question 25

How do bacterial cells protect themselves in hypertonic environments?
A) The cell wall prevents water loss
B) Bacteria cannot survive in hypertonic environments
C) They pump solutes out of the cell
D) Plasmolysis occurs, where the cytoplasm shrinks but does not destroy the cell wall

Answer 25

D) Plasmolysis occurs, where the cytoplasm shrinks but does not destroy the cell wall

Question 26

What structural component makes Gram-positive bacteria stain purple during Gram staining?
A) The thick peptidoglycan layer
B) The outer membrane
C) The presence of lipopolysaccharides
D) The presence of teichoic acids

Answer 26

A) The thick peptidoglycan layer

Question 27

Which part of the bacterial flagella is responsible for embedding it into the cell envelope?
A) The filament
B) The basal body
C) The hook
D) The cap

Answer 27

B) The basal body

Question 28

Which of the following statements best describes the process of flagella synthesis?
A) Flagellin molecules are transported through the filament and self-assemble at the tip
B) Flagella subunits are synthesized at the base of the filament
C) Flagella synthesis does not require any energy
D) The flagella structure is not formed by protein subunits

Answer 28

A) Flagellin molecules are transported through the filament and self-assemble at the tip