C2 Sample Questions from Brock

Question 1

An organism of the genus Staphylococcus is ______, while an organism of the genus Spirochaete is ____.
A) spherical / rod shaped
B) rod shaped / coiled
C) spherical / coiled
D) coiled / spherical

Answer 1

C) spherical / coiled

Staphylococcus bacteria are cocci, meaning they are spherical. Spirochaete are spiral-shaped, often described as coiled.

Question 2

Bacteria with type IV pili
A) possess tubular or stalk-like extensions of their cells.
B) likely exhibit twitching motility.
C) have capsules that promote dehydration.
D) live in aquatic environments.

Answer 2

B) likely exhibit twitching motility.

Type IV pili are known for their role in twitching motility, a type of bacterial movement involving extension and retraction of the pili.

Question 3

The terms “run”, and “tumble” are generally associated with
A) eukaryotic cells.
B) nutrient transport.
C) chemotaxis.
D) clustering of certain rod-shaped bacteria.

Answer 3

C) chemotaxis.

“Run” and “tumble” refer to the movement patterns of bacteria during chemotaxis, where they move towards or away from chemical stimuli. A run is a straight movement, while a tumble is a random change in direction.

Question 4

The morphology of a cell influences its
A) motility.
B) metabolism.
C) surface-to-volume ratio.
D) motility and surface-to-volume ratio.

Answer 4

D) motility and surface-to-volume ratio.

Cell morphology impacts both motility (e.g., streamlined shapes for swimming) and surface-to-volume ratio (e.g., smaller cells have higher ratios, facilitating nutrient exchange).

Question 5

Compared to Eukaryotes, Bacteria and Archaea have _____ surface-to-volume ratios, causing _____ nutrient exchange.
A) lower / lower
B) lower / higher
C) higher / lower
D) higher / higher

Answer 5

D) higher / higher

Bacteria and Archaea are generally smaller than eukaryotes, leading to a higher surface-area-to-volume ratio. This higher ratio facilitates a higher rate of nutrient exchange.

Question 6

The cytoplasmic membrane could best be described as
A) an impermeable barrier.
B) a passive conduit for intracellular transport.
C) a highly selective permeability barrier.
D) a rigid structure that protects the cell.

Answer 6

C) a highly selective permeability barrier.

The cytoplasmic membrane is selectively permeable, regulating the passage of substances into and out of the cell. It’s not simply a passive conduit nor an impermeable barrier.

Question 7

The use of the Gram stain in microbiology is important because it differentiates
A) Bacteria from each other
B) prokaryotic from eukaryotic cells.
C) bacterial cells with different types of cell walls.
D) archaeal cells with different types of metabolism.

Answer 7

C) bacterial cells with different types of cell walls.

The Gram stain differentiates bacteria based on cell wall structure (Gram-positive vs. Gram-negative), not between prokaryotes and eukaryotes or archaeal metabolism.

Question 8

Some archaea have unique phospholipids in their cytoplasmic membrane that
A) form a monolayer due to the presence of diglycerol tetraethers.
B) form a bilayer due to the presence of sterols.
C) form a stable ring structure due to the presence of crenarchaeol.
D) form a bilayer due to the presence of phosphatidylethanolamine

Answer 8

A) form a monolayer due to the presence of diglycerol tetraethers.

Some archaea have unique lipids called diglycerol tetraethers that span the entire membrane, forming a monolayer instead of the typical bilayer.

Question 9

You have discovered a new microorganism and would like to classify it as a eukaryote or a prokaryote. To investigate this question, you prepare a slide with a simple stain and view it with a light microscope with a 40X objective lens and 10X ocular lens. You also prepare a control slide using Saccharomyces cerevisiae (a unicellular eukaryote). You can see the cells on your control slide, but you don’t see cells when you look at your unknown microorganism. What can you conclude from this experiment?
A) The experiment failed to visualize the organism because the stain killed it.
B) Your new unknown microorganism is probably a virus.
C) The cells of the new unknown microorganism may be too small to see with the objective and ocular lenses you used.
D) The new unknown microorganism is probably an archaeon.

Answer 9

C) The cells of the new unknown microorganism may be too small to see with the objective and ocular lenses you used.

A 40X objective with a 10X ocular gives 400X magnification, which may not be sufficient to visualize very small prokaryotic cells. The other options are less likely given the information provided.

Question 10

You are given an electron micrograph of a bacterial cell. In the micrograph you can clearly see three thin layers of different densities surrounding the cell. Based on the micrograph, you can infer that this cell is ________ and would appear ________ after application of the Gram stain procedure.
A) gram-positive / purple
B) gram-negative / pink
C) gram-positive / pink
D) gram-negative / purple

Answer 10

B) gram-negative / pink

Three distinct layers in the electron micrograph indicate a gram-negative cell wall (inner membrane, periplasm, outer membrane). Gram-negative bacteria stain pink.

Question 11

The cell wall of a Gram-positive bacterium is composed of a thick _________ layer.
A) protein
B) poly-β-hydroxybutyric acid (PHB)
C) lipopolysaccharides (LPS)
D) peptidoglycan

Answer 11

D) peptidoglycan

Gram-positive bacteria have a thick peptidoglycan layer in their cell wall.

Question 12

You have discovered a new coccoid-shaped microorganism with no nucleus, a rigid cell wall, and a diameter of 2 μm. Chemical tests reveal that its cell wall does NOT contain peptidoglycan. The new microorganism is
A) most likely a bacterium.
B) most likely a eukaryote.
C) most likely an archaeon.
D) either a bacterium or an archaeon.

Answer 12

C) most likely an archaeon.

The description fits a prokaryote due to the lack of a nucleus and the presence of a rigid cell wall. The lack of peptidoglycan points to an archaeon, as bacterial cell walls are primarily composed of peptidoglycan.

Question 13

The lipopolysaccharide (LPS) layer is found ONLY in the cell walls of
A) gram-positive Bacteria.
B) gram-negative Bacteria.
C) Archaea.
D) Eukarya.

Answer 13

B) gram-negative Bacteria.

Lipopolysaccharide (LPS) is a characteristic component of the outer membrane of gram-negative bacteria.

Question 14

An endotoxin is
A) the toxic portion of the LPS.
B) a toxin produced within archaeal cells.
C) a toxin known for its primary attack on the epidermis of mammals.
D) a toxin produced in the periplasm of most bacteria.

Answer 14

A) the toxic portion of the LPS.

Endotoxin refers to the lipid A portion of LPS, which is responsible for the toxic effects of gram-negative bacterial infections.

Question 15

Using phase contrast microscopy on a wet mount of live cells, you observe motile bacilli moving rapidly and randomly through the field of view, changing directions after a brief tumble and taking off in a different direction. These cells are exhibiting _______ motility.
A) twitching
B) swimming
C) gliding
D) twitching or gliding

Answer 15

B) swimming

The described movement, with runs and tumbles, is characteristic of swimming motility mediated by flagella.

Question 16

Which of the following statements is FALSE?
A) A flagellar protein subunit is flagellin.
B) In flagellar motion, the basal body acts as a motor.
C) Flagellar rotation generates ATP.
D) The hook is the wider region at the base of the flagellum.

Answer 16

C) Flagellar rotation generates ATP.

Flagellar rotation is powered by ATP hydrolysis; it does not generate ATP. The other statements are true.

Question 17

Which of the following statements is TRUE?
A) Fimbriae are generally longer and less numerous than flagella.
B) Fimbriae are involved in genetic exchange between cells.
C) Hami are common in Bacteria but not found in Archaea.
D) Fimbriae are usually shorter than flagella whereas pili are involved in genetic exchange.

Answer 17

D) Fimbriae are usually shorter than flagella whereas pili are involved in genetic exchange.

Fimbriae are shorter and more numerous than flagella and are primarily for attachment. Pili are involved in processes like conjugation (genetic exchange). Hami are archaeal structures.

Question 18

Cellular inclusions in prokaryotic cells serve to
A) store energy rich compounds.
B) protect DNA.
C) position cells in the appropriate environment for survival.
D) store energy rich compounds and position cells in the appropriate environment for survival.

Answer 18

D) store energy rich compounds and position cells in the appropriate environment for survival.

Inclusions can store energy reserves (e.g., polyhydroxybutyrate aka PHB) or help with positioning (e.g., gas vesicles for buoyancy).

Question 19

A major function of prokaryotic gas vesicles is to
A) confer buoyancy on cells by decreasing their density.
B) serve as a reservoir for oxygen and carbon dioxide.
C) keep the cell’s organelles separated during flagellar motion.
D) store oxygen for aerobic growth when oxygen becomes depleted in the environment.

Answer 19

A) confer buoyancy on cells by decreasing their density.

Gas vesicles regulate buoyancy, allowing aquatic microorganisms to position themselves optimally in the water column.

Question 20

What is the biological function of endospores?
A) They are bacterial reproductive structures.
B) They enable organisms to endure extremes of temperature, drying, and nutrient depletion.
C) They transport toxins.
D) Endospores can serve as reproductive structures, enable survival in harsh environments, and transport toxins.

Answer 20

B) They enable organisms to endure extremes of temperature, drying, and nutrient depletion.

Endospores are dormant, resistant structures formed by certain bacteria for survival in harsh conditions, not for reproduction or toxin transport.

Question 21

__________ are charged molecules that are partially responsible for the ___________ charge of the gram-positive bacterial cell surface.
A) Diaminopimelic acids / positive
B) Teichoic acids / negative
C) Phospholipids / negative
D) Peptide interbridges / neutral

Answer 21

B) Teichoic acids / negative

Teichoic acids, found in Gram-positive cell walls, contribute to the negative charge of the cell surface.

Question 22

Although the inner leaflet of the gram-negative outer membrane is composed mainly of phospholipids, the outer leaflet of the outer membrane contains
A) pseudopeptidoglycans.
B) lipoteichoic acids.
C) poly-β-hydroxybutyric acids (PHB).
D) lipopolysaccharides (LPS).

Answer 22

D) lipopolysaccharides (LPS).

The outer leaflet of the Gram-negative outer membrane is characterized by the presence of LPS.

Question 23

Which is/are a function(s) of the cytoplasmic membrane in prokaryotes?
A) It functions as a permeability barrier.
B) It is an anchor for many proteins involved in bioenergetic reactions and transport.
C) It is a major site of energy conservation.
D) It serves as a permeability barrier, a docking station for proteins involved in bioenergetics reactions and transport, and a site for energy conservation.

Answer 23

D) It serves as a permeability barrier, a docking station for proteins involved in bioenergetics reactions and transport, and a site for energy conservation.

The cytoplasmic membrane performs all these functions.

Question 24

Mitochondria and hydrogenosomes are similar in that they both
A) are the site of energy production in eukaryotic cells.
B) evolved via endosymbiosis of bacterial cells.
C) are the site of aerobic respiration.
D) evolved via endosymbiosis and are sites for aerobic respiration and energy production.

Answer 24

B) evolved via endosymbiosis of bacterial cells.

Both mitochondria and hydrogenosomes are believed to have originated from endosymbiotic bacteria. Not all are involved in aerobic respiration.

Question 25

The membrane-enclosed compartments that contain digestive enzymes in eukaryotic cells are called
A) cristae.
B) mitosomes.
C) lysosomes.
D) stromas.

Answer 25

C) lysosomes.

Lysosomes contain digestive enzymes for breaking down cellular waste and foreign materials.

Question 26

The peptide interbridge crosslinking between peptidoglycan layers is found ONLY in the cell walls of
A) Archaea.
B) Eukarya.
C) gram-positive Bacteria.
D) gram-negative Bacteria.

Answer 26

C) gram-positive Bacteria.

Peptide interbridges in peptidoglycan are characteristic of gram-positive bacteria.

Question 27

Type IV pili are involved in
A) attachment of cells to surfaces.
B) twitching motility.
C) pathogenesis.
D) attachment to surfaces, twitching motility, and pathogenesis.

Answer 27

D) attachment to surfaces, twitching motility, and pathogenesis.

Type IV pili are versatile and play roles in all these processes.

Question 28

The rigid layer that is present in the cell walls of Bacteria that is primarily responsible for the strength of the wall is known as
A) pseudomurein.
B) S-layer.
C) cellulose.
D) peptidoglycan.

Answer 28

D) peptidoglycan

Peptidoglycan provides rigidity and strength to bacterial cell walls.

Question 29

Some of the intestinal symptoms elicited by pathogens such as Salmonella, Shigella, and Escherichia are due to the presence of
A) pseudomurein.
B) S-layers.
C) lipopolysaccharides.
D) peptidoglycan.

Answer 29

C) lipopolysaccharides.

LPS (endotoxin) in the outer membrane of Gram-negative bacteria like Salmonella, Shigella, and Escherichia contributes to intestinal inflammation and other symptoms.

Question 30

While examining cellular material, you find that organelle DNA is present. What organelle(s) must be within the sample?
A) lysosomes
B) rough or smooth endoplasmic reticulum
C) chloroplasts or mitochondria
D) Golgi complex

Answer 30

C) chloroplasts or mitochondria

Chloroplasts and mitochondria are the only organelles besides the nucleus that contain their own DNA.

Question 31

Which of the following is evidence for the endosymbiotic theory?
A) Mitochondria have circular DNA.
B) The nucleus is surrounded by a nuclear membrane.
C) Chloroplasts have thylakoids.
D) The rough endoplasmic reticulum has ribosomes.

Answer 31

A) Mitochondria have circular DNA.

The circular DNA in mitochondria resembles bacterial DNA, supporting the endosymbiotic origin of these organelles. The other options are features of eukaryotes but don’t specifically support endosymbiosis.

Question 32

Archaeans have archaella that rotate like bacterial flagella though they
A) have greater diameters than bacterial flagella.
B) are longer than bacterial flagella.
C) only rotate in one direction.
D) consist of multiple protein types.

Answer 32

D) consist of multiple protein types.

While functionally similar to bacterial flagella, archaella are composed of different proteins and are thinner.

Question 33

You find endospores of a particular species. Which of the following is most likely TRUE of this species?
A) It is an archaean.
B) It is a gram-positive bacterium.
C) It is a gram-negative bacterium.
D) It is equally likely to be an archaean, a gram-positive bacterium, or a gram-negative bacterium.

Answer 33

B) It is a gram-positive bacterium.

Endospore formation is primarily observed in certain gram-positive bacteria, particularly those in the genera Bacillus and Clostridium.

Question 34

T/F: Chemotaxis is a sensory response affecting the rotational direction of the flagellar motor.

Answer 34

True

Question 35

T/F: Mitochondria and chloroplasts have their own DNA and ribosomes, which supports the endosymbiotic hypothesis.

Answer 35

True

Question 36

T/F: Viewing the shape of a bacterial or archaeal cell using a microscope gives a great deal of information about the metabolism and lifestyle of the organism.

Answer 36

False.

While shape offers some clues, it doesn’t provide extensive information about metabolism and lifestyle. More detailed analyses are needed.

Question 37

T/F: Smaller prokaryotic cells generally grow faster than larger ones due to a higher surface-area-to-volume ratio.

Answer 37

True

Question 38

T/F: Despite the invariance of the backbone of peptidoglycan, there are more than 100 different types of peptidoglycan.

Answer 38

True

Question 39

T/F: In general, swimming is performed with flagella, whereas gliding uses other cellular components such as pili.

Answer 39

True