Microbiology Chapter 4 HW

1. What is a biofilm? A bacterial cell that secretes an extensive network of fibers around its cell wall Free-floating bacteria that move through the blood to other sites A group of bacteria that accumulate in layers and secrete an protective extracellular material Correct A layer of sugars that persist even after bacteria have been killed by antibiotics

A group of bacteria that accumulate in layers and secrete an protective extracellular material Correct

2. After Gram's iodine is added, what color do the cells appear under a light microscope? All cells appear pink/red All cells appear colorless All cells appear purple Some cells may be purple and some may be pink/red

All cells appear purple

1. Endospores can survive _______. lack of water (dessication) exposure to disinfectants All of the choices are correct. exposure to high temperatures

All of the choices are correct.

4. Microenvironments are created within the biofilm based on _______. oxygen gradient nutrient concentration pH gradient All of the choices are correct.

All of the choices are correct.

1. The patient's hand went without adequate blood supply for too long due to damage to which vessel type?

Arteries

3. Why are biofilms important in infectious disease? Most microbes cannot cause disease without other microbes present. The secreted extracellular "gunk" is highly damaging to tissues. Bacteria in biofilms are often protected from antibiotics.

Bacteria in biofilms are often protected from antibiotics.

4. Which external structure directly impacts the effectiveness of the host immune system? Capsule Flagellum Pilus Fimbria

Capsule

3. Which staining method was used to determine the identity of the causative agent? Simple stain Flagellar stain Acid fast stain Capsule stain

Capsule stain

1. What is the stimulus for chemotaxis? Chemicals Sound Temperature Light

Chemicals

What does the capsule typically look like on a stained smear when viewing under the light microscope? Dark circles surrounding the cell wall Clear halos around the cells Colored layers of threadlike structures surrounding the cell

Clear halos around the cells

Which of the following is an example of a biofilm commonly found in the human body? Dental plaque Salivary secretions Ear wax Yellow or green discharge

Dental plaque

4. What general type of stain is used to separate types of bacteria based on their cellular structures? Negative Acidic Differential Simple

Differential

3. The production of which substance leads to thickening of the biofilm over time? Lysozyme IL-4 Exopolymer Exotoxin

Exopolymer

1. True or False: Bacteria are larger than human cells.

False Bacteria are much smaller than eukaryotic cells.

2. True or False: Bacteria are only visible with an electron microscope.

False Bacteria are visible with the light microscope.

5. True or False: Biofilms are composed of a single bacterial species.

False In the natural environment, biofilms often consist of different types of organisms that function together in the cycling of nutrients.

4. True or False: The presence of flagella can be determined by a Gram stain.

False Special stains are needed to visualize flagella

1. True or False: When the bacterial glycocalyx is easily removed, it is called a capsule.

False When the bacterial glycocalyx is easily removed, it is called a slime layer.

4. True or False: Ordinarily the presence of bacteria in the blood and CSF is a common and expected result.

False these two body compartments are typically free of microorganisms.

3. True or False: All bacteria can be classified as either gram-positive or gram-negative.

False Some bacteria are classified as acid-fast, and others lack cell walls completely.

4. True or False: The thinner peptidoglycan layer of gram-positive bacteria allows the crystal-violet-iodine complex to leave the cell.

False. Gram-positive bacteria have a thicker peptidoglycan layer that traps the crystal-violet-iodine complex inside the cell.

2. Which of the following structures leads to reversible binding of bacterial cells to a surface? Fimbriae and flagella Fimbriae Spike proteins Flagella

Fimbriae and flagella

1. Which of these pairs is incorrectly matched? Capsule-protective layer Flagellum-motility Fimbriae-motility Pilus-attachment

Fimbriae-motility

2. What motility structure is used for bacterial chemotaxis? Flagella Fimbriae Pili Cilia

Flagella

2. Which of the following bacteria possess capsules? Streptococcus pneumoniae Lactobacillus acidophilus Haemophilus influenzae and Streptococcus pneumoniae Haemophilus influenzae

Haemophilus influenzae and Streptococcus pneumoniae

Some Species of Bacteria

Have endospores, capsule, Pili, and flagella

All Species of Bacteria

Have ribosomes, cell membranes, and DNA

3. Which of the following statements describes Clostridium perfringens?

It is a gram-positive organism.

A culture of Klebsiella colonies is smooth, indicating the presence of a capsule. A culture of Pseudomonas shows rough colonies. Based on this information alone, which species is likely to be more pathogenic? Klebsiella Pseudomonas

Klebsiella

1. Which of the following surfaces have nutrients available that encourage the development of biofilms? Moist abiotic surfaces Moist abiotic surfaces and biotic surfaces such as plant and animal tissue Dry abiotic surfaces Biotic surfaces such as plant and animal tissue

Moist abiotic surfaces and biotic surfaces such as plant and animal tissue

2. If the Gram's iodine step was skipped in this technique, what would likely be seen under the microscope? Most cells would appear blue. Most cells would appear red/pink. All cells would appear colorless. Most cells would appear purple.

Most cells would appear red/pink.

1. SLE has been found to be caused by ______.

None of these choices.

1. Why must fresh cells be used when performing a Gram stain? Fresh cells do not smell as badly as older cells. Old cells may not Gram stain properly. As cells age, they won't stick to the slide. All of these are reasons why fresh cells must be used for Gram staining.

Old cells may not Gram stain properly.

3. A cell contains a fertility (F) plasmid that allows it to produce a structure for exchanging DNA with another cell. What structure is coded for by the genes of this plasmid? Capsule Fimbria Pilus Flagellum

Pilus

2. Select all of the characteristics of fimbriae. Allow bacterial cells to avoid phagocytosis Short appendages Allow bacterial cells to colonize host tissues Participate in biofilm formation Hollow tubes for material exchange

Short appendages Allow bacterial cells to colonize host tissues Participate in biofilm formation

5. Which of the following can increase the binding of bacterial cells to a surface, leading to the thickening of a biofilm? Slime layer and capsules Pseudopods Capsules Slime layer

Slime layer and capsules

4. If a few drops of nutrient solution are added to one side of a bacterium's environment, what will happen? The bacterium will run in a straight direction all the way to the nutrient solution. The bacterium will tumble until it reaches the nutrient. The bacterium will rotate its flagella clockwise most of the time The bacterium will have longer runs towards the nutrient, but it will still tumble at times.

The bacterium will have longer runs towards the nutrient, but it will still tumble at times.

3. What determines whether a bacterium "runs" or "tumbles" through its environment? The direction of flagellar rotation Whether a cell is gram-positive or gram-negative The number of cilia present on a cell The number of flagella present on a cell The position of flagella within the cell wall\

The direction of flagellar rotation

4. Why is the capsule considered a virulence factor? It provides motility to bacterial cells, allowing them to spread throughout the host organism. The presence of the capsule allows a bacterium to evade the immune system and cause damage to the host. It is released by the bacterium, killing any adjacent host cells.

The presence of the capsule allows a bacterium to evade the immune system and cause damage to the host.

1. True or False: A capsule is a type of glycocalyx.

True

2. True or False: Encapsulated bacterial cells generally have greater pathogenicity.

True

2. How did the patient most likely become exposed to the endospores of Clostridium perfringens?

Via soil-contaminated portions of the power take-off

1. When is sporulation initiated by spore-forming bacteria? When the organism is exposed to sunlight When nutrients are depleted or conditions become adverse When the organism is placed in a hypertonic solution As a normal part of cellular growth

When nutrients are depleted or conditions become adverse

4. It was hypothesized that bacteria wound up in the CSF due to the patient's lack of _______. lysosomes histamine production antibody production

antibody production

5. In the next phase of spore formation, _______ enters the cortex and _______ leaves the cortex. water; calcium peptidoglycan; cell membrane calcium; water protein; lipids

calcium; water

5. Rod-shaped bacteria _______. can be either gram-positive or gram-negative are never gram-positive or gram-negative are all gram-negative are all gram-positive

can be either gram-positive or gram-negative

3. In the case study, which of the following clinical signs suggested the patient was suffering from gas gangrene? cell wall glycocalyx mitochondria cytoplasm

cytoplasm

1. The differential stage of the Gram stain is the application of ______. safranin ethanol crystal violet iodine

ethanol

2. Clostridium perfringens is the causative agent of ______.

gas gangrene

2. When spore formation begins, the vegetative cell is referred to as the _______. parent cell father cell mother cell haploid cell

mother cell

3. The primary function of flagella is for ______. motility transferring DNA to other cells maintaining cell shape attachment

motility

4. Biofilms are found _______. on teeth on the walls of swimming pools on a variety of surfaces including shower curtains, the walls of swimming pools, and teeth on shower curtains

on a variety of surfaces including shower curtains, the walls of swimming pools, and teeth

4. The cortex is formed from _______. peptidoglycan protein cell membrane flagellar proteins

peptidoglycan

3. Capsules help many pathogenic bacteria resist the action of _______. phagocytes antigen presenting cells red blood cells astrocytesNot

phagocytes

6. In the final step of spore formation, a _______ coat forms around the cortex. protein lipopolysaccharide lipid membrane peptidoglycan

protein

3. When ethanol is applied correctly, gram-positive cells appear ______ and gram-negative cells appear ______. purple; pink/red pink/red; purple colorless; purple purple; colorless

purple; colorless

3. The term used to describe a cluster of circular bacteria is _________. streptobacilli staphylococci streptococci vibrio

staphylococci

2. Autosplenectomy is caused by _______. a viral infection lysozyme activity the action of autoantibodies bacterial exotoxins

the action of autoantibodies

3. The developing spore is surrounded by _______. proteins produced by the mother cell the membrane of the mother cell the cytoplasm of the mother cell the cell wall of the mother cell

the membrane of the mother cell