Mastering Microbiology Ch 4

Which of the following statements about bacterial flagella is true? a. Bacteria can only rotate flagella clockwise. b. Bacteria can only rotate flagella counterclockwise. c. Bacteria can rotate 360 degrees. d. Bacteria work by undulating.

Taxis is: a. caused by the undulating motion of a bacterium. b. another word for stimulus. c. movement towards or away from a stimulus. d. another term for bacterial tumbling.

Which of the following terms refers to a bacterium moving towards a light source? a. Positive phototaxis b. Positive chemotaxis c. Negative chemotaxis d. Negative phototaxis

As a bacterium approaches a food source, one would expect: a. flagella to stop spinning. b. runs to become more frequent. c. flagella to rotate clockwise more frequently. d. tumbles to become more frequent.

Why are receptors on the cell surface necessary for bacterial movement? a. The receptors actually spin the flagella. b. The receptors sense the stimulus and send signals to the flagella. c. The bacterium contains receptors that are sensitive to light. d. The receptors physically alter shape to steer the bacterium.

What structural part of a bacterial flagellum is composed of flagellin? a. Rod b. Basal body c. Filament d. Hook

How are Gram-positive and Gram-negative flagella different? a. A Gram-positive flagellum does not have a membrane covering its filament; A Gram-negative flagellum does. b. A Gram-positive flagellum has only two rings in its basal body; Gram-negatives each have four. c. Each Gram-positive flagellum contains a hook; gram-negatives do not. d. Flagella are only found in Gram-negative bacteria

The rings: a. are curved structures into which each filament inserts. b. anchor the flagellum to the cell membrane. c. are covered by a membrane. d. are comprised of globular proteins called flagellin.

The basal body is comprised of which structural component(s) of flagella? a. Filament b. Rod and Rings c. Rod and Hook d. Rod e. Rings f. Hook

Pathogenic bacteria: a. are unique because they have a membrane covering the filament. b. have a unique basal body structure. c. can be identified and classified by differences in their flagellar proteins. d. do not have flagella.

Which of the following molecules is shared by both Gram-positive and Gram-negative organisms? a. lipid A b. lipoteichoic acid c. lipopolysaccharide d. N-acetylmuramic acid

Amoxicillin is an antibiotic that inhibits the formation of peptide cross-links. Amoxicillin, therefore, would most likely inhibit the growth of __________. a. only Gram-negative organisms b. neither Gram-positive nor Gram-negative organisms c. both Gram-positive and Gram-negative organisms d. only Gram positive organisms

Porins are present in ______________bacteria because, in these organisms, molecules entering the cell must pass through an extra layer of ___________. a. Gram-negative; membrane b. both Gram-negative and Gram-positive; membrane c. Gram-negative; peptidoglycan d. Gram-positive; peptidoglycan e. Gram-positive; membrane

You are observing a Gram stain of spherical-shaped microorganisms that are linked in a chain and stain purple. How would you describe these bacteria using the correct terminology for the cell shape and arrangement? a. gram-positive streptococci b. gram-negative staphylococci c. gram-positive coccobacilli d. gram-positive tetrads

Which membrane transport mechanism requires ATP? a. active transport b. osmosis c. simple diffusion d. facilitated diffusion

Which statement regarding the structure or function of ribosomes is correct? a. Ribosomes are the sites of lipid biosynthesis in both prokaryotes and eukaryotes. b. Ribosomes are found both free-floating and attached to the rough endoplasmic reticulum in eukaryotes and in prokaryotes. c. The ribosomes in the prokaryote are slightly larger than those found in the eukaryotic endoplasmic reticulum. d. In eukaryotes, the ribosomes found in chloroplasts and mitochondria are 70S ribosomes, which are similar in size to prokaryotic ribosomes.

Which of the following is found in the cytoplasm of prokaryotic cells but is ABSENT from the cytoplasm of eukaryotic cells? a. DNA b. a cytoskeleton c. enzymes d. water

Which of the following statements accurately describes specific bacterial cell walls? a. In gram-negative bacteria, the thin layer of peptidoglycan is surrounded by an external membrane made of phospholipids, lipopolysaccharides, and proteins. b. Gram-negative bacterial cell walls contain teichoic acids, whereas the cell walls of gram-positive bacteria do not. c. The cell walls of gram-negative bacteria contain many more layers of peptidoglycan than those of gram-positive bacteria. d. In bacteria with acid-fast cell walls, the carboxylic acid in the walls forms a layer outside a thin layer of hydrophilic polypeptides.