Week 7: Microbes & Infection

Question 1

T/F: The coat of a virus consists of protein.

Answer 1

True

Question 2

T/F: A “bacillus” is a spiral-shaped bacterium.

Answer 2

False

Question 3

T/F: A bacterial cell wall contains chitin.

Answer 3

False

Question 4

T/F: A prokaryotic cell is identified by the presence of ribosomes.

Answer 4

False - Ribosomes are found in both prokaryotic and eukaryotic cells.

Question 5

T/F: Viruses can transform host cells into tumor cells.

Answer 5

True

Question 6

T/F: Fungi are eukaryotic cells whose cell wall contains peptidoglycan.

Answer 6

False - The cell wall of fungi contains chitin. Peptidoglycan is found in bacterial cell walls.

Question 7

T/F: Bacteria feed off living matter only.

Answer 7

False

Question 8

T/F: The most common type of viral infection is lytic.

Answer 8

True

Question 9

T/F: Prokaryotic cells contain a nucleus but no membrane-bound organelles.

Answer 9

False - The nucleus is a membrane-bound organelle and thus is not present in prokaryotes.

Question 10

T/F: Fungi generally only cause mild, superficial infections in healthy hosts.

Answer 10

True

Question 11

In which symbiotic relationship does one partner benefit while the other is unaffected?

a Infection

b Parasitic

c Commensal

d Mutualistic

Answer 11

c Commensal

Question 12

What benefits do the normal flora receive from the host?

Nutrition
Prevent colonisation and infection of the host by pathogens
Provide nutrients such as vitamins B and K
Living space

Answer 12

Nutrition
Living space

Question 13

The normal flora can be found in/on which of the following:

upper respiratory tract (i.e. nose, pharynx)
lungs and uterus
urinary bladder
warmer, more damp areas of the skin
mouth and stomach
the upper reprodcutive tract
large, but not the small, intestine

Answer 13

upper respiratory tract (i.e. nose, pharynx)
warmer, more damp areas of the skin
mouth and stomach

Question 14

T/F: Transient microbes are unable to colonise body surfaces.

Answer 14

True

Question 15

A pathogen has a _____ relationship with the host.

a mutualistic

b transient

c commensal

d parasitic

Answer 15

d parasitic

Question 16

T/F: Infectious disease is transmissible disease.

Answer 16

False - “Infectious” refers to tissue damage caused by a pathogen, not an ability to be transmitted.

Question 17

Which terms have been correctly identified?

Infection = invasion of a body surface by a pathogen
Infectious disease = invasion of a body surface by a pathogen involving tissue damage
Colonisation = establishment and growth of a microbe on a body surface involving tissue damage
Infection = establishment and growth of a microbe on a body surface
Colonisation = establishment and growth of a microbe on a body surface

Answer 17

Infection = invasion of a body surface by a pathogen
Infectious disease = invasion of a body surface by a pathogen involving tissue damage
Colonisation = establishment and growth of a microbe on a body surface

Question 18

The normal flora can cause an opportunistic infection when:

their own defences are compromised
their ecological balance is upset and a specific population multiplies to high numbers
host defences are compromised
they penetrate a body surface and colonise deeper tissues
they are relocated to body areas they are normally excluded from
they colonise a body surface different to their usual location
they turn to the dark side

Answer 18

their ecological balance is upset and a specific population multiplies to high numbers
host defences are compromised
they penetrate a body surface and colonise deeper tissues
they are relocated to body areas they are normally excluded from

Question 19

T/F: Compromised surface barriers increase host susceptibility to infection.

Answer 19

True

Question 20

Opportunistic pathogens, that do not usually cause disease in otherwise healthy hosts, include:

transient microbes
conventional pathogens
environmental microbes
normal flora

Answer 20

transient microbes
environmental microbes
normal flora

Question 21

T/F: A more virulent microbe has a high infectious dose.

Answer 21

False - A more virulent microbe can establish an infection with a low number of organisms.

Question 22

T/F: A symptom is an objective change in a patient that can be observed and measured.

Answer 22

False - A symptom is the subjective patient experience.

Question 23

T/F: If a host has memory lymphocytes that recognise a particular pathogen they are likely to experience an asymptomatic or subclinical infection the next time they encounter that pathogen.

Answer 23

True - Memory lymphocytes will mediate a secondary immune response that prevents, or reduces the severity of, an infection.

Question 24

T/F: Whether an infection occurs depends on host susceptibility, pathogen virulence and environmental conditions.

Answer 24

True

Question 25

T/F: A major cause of tissue damage by the host can be the process of inflammation.

Answer 25

True

Question 26

T/F: Viruses generally kill a host cells upon exit, causing tissue damage and promoting inflammation.

Answer 26

True

Question 27

T/F: Most pathogens can use multiple portals of entry into the body.

Answer 27

False - Most pathogens have a preferred portal of entry.

Question 28

The most common portal of entry is the:

a respiratory tract

b urinary tract

c gastrointestinal tract

d skin

Answer 28

a respiratory tract

Question 29

In order to establish an infection, a pathogen must first

a be able to use the host as a food resource

b avoid host defences

c attach to a body surface

d multiply to a critical population size

Answer 29

c attach to a body surface

Question 30

Pathogens can overcome host INNATE defences by:

• using enzymes to break though surface barriers
• using enzymes to destroy host anitbodies
• killing phagocytes with toxins
• changing their surface proteins
• degrading phagocyte digestive enzymes with their own enzymes

Answer 30

• using enzymes to break though surface barriers
• killing phagocytes with toxins
• degrading phagocyte digestive enzymes with their own enzymes`

Question 31

Damage to the host can be caused:

• indirectly by the activity of the pathogen
• directly by the activity of the host defences
• by perforins and granzymes from cytotoxic T cells or NK cells
• through the lytic activity of viruses
• by enzymes dervied from the pathogen or from host phagocytes
• by toxins that kill host cells

Answer 31

• by perforins and granzymes from cytotoxic T cells or NK cells
• through the lytic activity of viruses
• by enzymes dervied from the pathogen or from host phagocytes
• by toxins that kill host cells

Question 32

Pathogens most commonly exit the host via the:

a respiratory or gastrointestinal tracts

b secretions from the eyes and nose

c urine and faeces

d skin

Answer 32

a respiratory or gastrointestinal tracts

Question 33

T/F: Viruses, but not bacteria, can overcome host defences by changing their surface antigens.

Answer 33

False- Both viruses and bacteria can undergo antigenic variation.

Question 34

T/F: Bacteria release enzymes that can kill phagocytes.

Answer 34

True

Question 35

T/F: In an acute infection, host defences are never able to clear the pathogen.

Answer 35

False

Question 36

T/F: Pathogens cannot be transmitted during the incubation period of an infection.

Answer 36

False - Pathogens can be transmitted during any period, as long as the pathogen is multiplying.

Question 37

T/F: During the latent period of a chronic infection, the pathogen does not multiply and cannot be transmitted and the host is asymptomatic.

Answer 37

False - A chronic infection does not have a latent period.

Question 38

The phases of an acute infection occur in the following order:

a disease, incubation, prodromal, recovery
b recovery, prodromal, disease, incubation
c prodromal, recovery, incubation, disease
d incubation, prodromal, disease, recovery

Answer 38

d incubation, prodromal, disease, recovery

Question 39

A chronic infection generally results in:

a no tissue damage after a chronic period of time

b a dormant period when the pathogen does not multiply or cause tissue damage

c ongoing, long-term tissue damage

d recurrent periods of acute, symptomatic disease

Answer 39

c ongoing, long-term tissue damage

Question 40

T/F: Herpes viruses cause latent infections and cannot be transmitted in the latent period becasue the virus is not multiplying.

Answer 40

True

Question 41

Define:

Microbes

Answer 41

Microorganisms, including bacteria, viruses, fungi, and protozoa, that can live in and on the human body, influencing health in both positive and negative ways.

Question 42

Define:

Microbes

Answer 42

Microscopic organisms, including bacteria, fungi, viruses, protozoa, and algae, that can only be seen with a microscope. They make up a significant portion of Earth’s biomass.

Question 43

Define:

Bacteria

Answer 43

Single-celled prokaryotic organisms that lack membrane-bound organelles. They are found in various environments, including the human body.

Question 44

Define:

Fungi

Answer 44

Eukaryotic organisms that can exist as single cells or multicellular forms, such as molds and yeasts. They can produce toxins and antibiotics, like penicillin.

Question 45

Define:

Viruses

Answer 45

Acellular microbes that do not have all the components necessary for independent cell function and metabolism. They are not considered living organisms outside of a host.

Question 46

Define:

Protozoa

Answer 46

Single-celled eukaryotic organisms that can live alone or in colonies, typically found in water. Examples include amoebas.

Question 47

Define:

Algae

Answer 47

Photosynthetic eukaryotic organisms that can be single-celled or multicellular, found mainly in aquatic environments.

Question 48

Define:

Eukaryotic cells

Answer 48

Cells with membrane-bound organelles, including a nucleus, Golgi apparatus, lysosomes, and mitochondria. Found in animals, plants, fungi, protozoa, and algae.

Question 49

Define:

Prokaryotic cells

Answer 49

Simpler cells that lack membrane-bound organelles and a nucleus. All bacteria are prokaryotes.

Question 50

Define:

Bacilli

Answer 50

Rod-shaped bacteria. The term is used in the names of rod-shaped bacterial species.

Question 51

Define:

Cocci

Answer 51

Spherical-shaped bacteria. The term is used in the names of spherical bacterial species.

Question 52

Define:

Spirilla

Answer 52

Spiral-shaped bacteria. This term is used for bacteria with a spiral shape.

Question 53

Define:

Spirochete

Answer 53

A specific type of spiral-shaped bacteria with a unique corkscrew motion.

Question 54

Define:

Vibrio

Answer 54

A comma-shaped or curved rod-shaped bacteria.

Question 55

Define:

Cell envelope

Answer 55

The outer layers surrounding a bacterial cell, including the cell membrane and cell wall.

Question 56

Define:

Peptidoglycan

Answer 56

A glycoprotein consisting of protein and carbohydrate groups that forms a mesh-like layer in the bacterial cell wall, targeted by certain antibiotics.

Question 57

Define:

Capsule

Answer 57

An additional outer layer found in some bacteria, which can be sticky or slippery and aids in host colonization.

Question 58

Define:

Pili

Answer 58

Hair-like structures on the surface of bacteria used for genetic material exchange and adherence to surfaces.

Question 59

Define:

Flagellum (Plural: Flagella)

Answer 59

A whip-like structure used by bacteria for locomotion and sometimes as a receptor for environmental changes.

Question 60

Define:

Nucleoid

Answer 60

A region within a bacterial cell where the genetic material, a single circular DNA chromosome, is located.

Question 61

Define:

Binary fission

Answer 61

The process of bacterial reproduction where a single bacterium divides into two identical daughter cells after DNA replication.

Question 62

Define:

Obligate parasites

Answer 62

Organisms that can only reproduce inside a host cell, relying on the host’s cellular machinery for replication.

Question 63

Define:

Naked viruses

Answer 63

Viruses that have a protein coat called a capsid surrounding their genetic material but lack an outer lipid envelope.

Question 64

Define:

Enveloped viruses

Answer 64

Viruses that have a phospholipid bilayer derived from the host cell’s plasma membrane surrounding their capsid, which may contain embedded proteins for host cell attachment.

Question 65

Define:

Capsid

Answer 65

A protein coat surrounding the genetic material of a virus. It helps protect the viral genome and facilitates attachment to host cells.

Question 66

Define:

Envelope

Answer 66

An outer lipid bilayer surrounding some viruses, derived from the host cell’s membrane, which may contain viral proteins that assist in infection.

Question 67

Define:

Lytic infection

Answer 67

A type of viral infection that results in the destruction (lysis) of the host cell, releasing new viral particles.

Question 68

Define:

Endocytosis

Answer 68

A process by which cells take in external substances, such as viruses, by engulfing them in a vesicle.

Question 69

Define:

Fusion

Answer 69

The process by which an enveloped virus merges its lipid envelope with the host cell membrane to gain entry into the cell.

Question 70

Define:

Exocytosis

Answer 70

The process by which viruses exit the host cell, often involving the budding off of new viral particles from the cell membrane.

Question 71

Define:

SARS-CoV-2

Answer 71

The virus responsible for COVID-19, characterized as an enveloped virus with spike proteins that facilitate attachment and entry into host cells.

Question 72

Define:

Spike proteins

Answer 72

Surface proteins on some viruses, such as SARS-CoV-2, that enable the virus to bind to specific receptors on the host cell, facilitating infection.

Question 73

Define:

Chronic or persistent infection

Answer 73

A type of viral infection where the virus is released slowly from the host cell without killing it, leading to a prolonged presence in the host.

Question 74

Define:

Latent state

Answer 74

A condition in which a virus remains dormant inside a host cell without replicating, potentially becoming reactivated later.

Question 75

Define:

Chitin

Answer 75

A carbohydrate derivative of glucose that forms a tough, protective shell around fungal cells, similar to the exoskeletons of insects and crustaceans.

Question 76

Define:

Yeast

Answer 76

Single-celled fungi that reproduce by budding. They are oval-shaped and can be found in various environments.

Question 77

Define:

Budding

Answer 77

A form of asexual reproduction in yeast where a new cell develops from an outgrowth or bud on the parent cell.

Question 78

Define:

Molds

Answer 78

Multicellular fungi that form a network of cells known as mycelium. They often appear as fuzzy or thread-like structures and are commonly seen on spoiled food.

Question 79

Define:

Mycelium

Answer 79

A network of fungal cells that forms the vegetative part of a fungus, such as mold. It helps in nutrient absorption and growth.

Question 80

Define:

Tinea

Answer 80

A type of fungal infection commonly known as athlete’s foot, which affects the skin between the toes.

Question 81

Define:

Candidiasis

Answer 81

A fungal infection caused by Candida species, which can occur in areas such as the mouth (thrush) or other mucosal surfaces.

Question 82

Define:

Immunocompromised

Answer 82

Individuals with weakened immune systems, such as those with HIV/AIDS, undergoing immunosuppressive treatments, or having chronic conditions like cancer or diabetes, who are more susceptible to severe fungal infections.

Question 83

Define:

Symbiosis

Answer 83

A relationship between two organisms living together in close association. In the context of microbes and humans, it refers to how microbes interact with humans, either beneficially, neutrally, or harmfully.

Question 84

Define:

Normal flora

Answer 84

Also known as resident flora, microbiota, or the microbiome. These are the microorganisms that regularly inhabit various parts of the human body and usually benefit the host by outcompeting harmful pathogens and assisting in various bodily functions.

Question 85

Define:

Transient microbes

Answer 85

Microorganisms that temporarily inhabit the body but do not establish a permanent presence. They may be picked up from the environment and do not necessarily contribute to the body’s normal flora.

Question 86

Define:

Commensalism

Answer 86

A type of symbiotic relationship where the microbe benefits from the interaction, while the host is unaffected (neither helped nor harmed).

Question 87

Define:

Mutualism

Answer 87

A symbiotic relationship where both the microbe and the host benefit from the interaction.

Question 88

Define:

Parasitism

Answer 88

A symbiotic relationship where the microbe benefits at the expense of the host, potentially causing harm or disease to the host.

Question 89

Define:

Communicable

Answer 89

Refers to diseases that can be transmitted from one person to another. Infectious diseases are not always communicable, as some, like tooth decay, do not spread between individuals.

Question 90

Define:

Lactobacillus

Answer 90

A type of bacteria found in the gastrointestinal tract and vagina. They metabolize glycogen to produce lactic acid, which maintains an acidic environment that inhibits the growth of harmful microbes.

Question 91

Define:

Escherichia coli (E. coli)

Answer 91

A bacterium commonly found in the large intestine. It helps with the metabolism of waste products and the production of essential vitamins, such as B-group vitamins and vitamin K, which are crucial for various bodily functions.

Question 92

Define:

Vitamin K

Answer 92

A vitamin produced by intestinal bacteria, essential for normal blood clotting. Infants are often given a injection at birth to ensure proper clotting until their gut flora is established.

Question 93

Define:

Butyrate

Answer 93

A fatty acid produced by intestinal microbes that serves as an energy source for epithelial cells in the large intestine. It supports cell health and reduces the risk of colon cancer by enhancing blood flow and immune function.

Question 94

Define:

Innate immune defenses

Answer 94

The body’s initial, non-specific defense mechanisms that respond quickly to pathogens. It includes physical barriers like skin and mucous membranes, as well as various immune cells and proteins.

Question 95

Define:

Adaptive immune defenses

Answer 95

The part of the immune system that develops a specific response to pathogens and improves its response with each exposure. It involves specialized cells and antibodies.

Question 96

Define:

Sign

Answer 96

An objective change in the body that can be observed or measured by a healthcare provider, such as a fever.

Question 97

Define:

Symptom

Answer 97

A subjective experience reported by the patient, such as pain or fatigue, which cannot be directly measured but indicates an underlying condition.

Question 98

Define:

Subclinical disease

Answer 98

An infection or disease that does not produce noticeable symptoms, often because the immune system has successfully contained the pathogen.

Question 99

Define:

Virulence

Answer 99

The capacity of a microbe to cause disease. It measures how harmful the microbe is and affects the severity of the disease it can cause.

Question 100

Define:

Infectious dose

Answer 100

The minimum number of pathogens required to cause an infection. A lower infectious dose indicates higher virulence.

Question 101

Define:

Conventional pathogens

Answer 101

Microbes that cause disease in individuals with normal immune defenses. Examples include viruses like the measles virus and bacteria like Neisseria gonorrhoeae.

Question 102

Define:

Opportunistic pathogens

Answer 102

Microbes that usually do not cause disease in healthy individuals but can lead to infections when the host’s immune defenses are compromised or when they colonize an unusual body site.

Question 103

Define:

Ecological imbalance

Answer 103

A disruption in the normal balance of microbes, allowing opportunistic pathogens to overgrow. For instance, the reduction of Lactobacillus bacteria can lead to the overgrowth of Candida albicans.

Question 104

Define:

Relocation

Answer 104

When normal flora microbes move to a part of the body where they are not typically found, potentially causing infections. For example, E. coli from the large intestine causing a urinary tract infection.

Question 105

Define:

Compromised host defenses

Answer 105

When the immune system or physical barriers are weakened, making the host more susceptible to infections. Factors include preexisting conditions, age, and compromised immune systems.

Question 106

Define:

Aspergillus

Answer 106

A genus of fungus found in various environments, such as damp hay, which can cause respiratory infections in immunocompromised individuals.

Question 107

Define:

Primary immune response

Answer 107

The initial reaction of the immune system to a pathogen, aimed at eliminating it and leading to recovery.

Question 108

Define:

Secondary immune response

Answer 108

A faster and more effective immune response that occurs upon subsequent exposure to a pathogen, often preventing disease or reducing its severity.

Question 109

Define:

Portal of Entry

Answer 109

The site through which a pathogen enters the body. Different pathogens may have preferred entry points for effective infection.

Question 110

Define:

Skin and Mucous Membranes

Answer 110

Physical barriers of the body that act as the first line of defense against pathogens. Pathogens may enter through openings in the skin or mucous membranes.

Question 111

Define:

Glycocalyx

Answer 111

A sticky substance secreted by some bacteria that helps them adhere to body surfaces and can contribute to the formation of biofilms, such as dental plaque.

Question 112

Define:

Viral Attachment

Answer 112

The process by which viruses bind to specific molecules on the surface of target cells to facilitate infection.

Question 113

Define:

Extracellular pathogens

Answer 113

Microbes that obtain nutrients from extracellular fluids and do not need to enter host cells to cause disease.

Question 114

Define:

Intracellular pathogens

Answer 114

Microbes that obtain nutrients from within host cells, causing disease by infecting and replicating inside these cells.

Question 115

Define:

Virulence factors

Answer 115

Traits or abilities of a pathogen that enable it to evade host defenses, cause damage, or persist within the host.

Question 116

Define:

Surface Barriers

Answer 116

Physical and chemical defenses of the body, such as the skin and mucous membranes, that prevent microbial entry and infection.

Question 117

Define:

Antigenic Variation

Answer 117

A mechanism by which pathogens alter their surface proteins to evade recognition by the immune system, leading to ongoing or repeated infections.

Question 118

Define:

Cytopathic Effects

Answer 118

Direct damage caused by pathogens, particularly viruses, which leads to the death of host cells.

Question 119

Define:

Fibrosis

Answer 119

Formation of excess fibrous connective tissue in response to chronic inflammation, leading to scarring and loss of function.

Question 120

Define:

Portal of Exit

Answer 120

The route through which a pathogen exits the host’s body to spread to new hosts, commonly through respiratory or digestive tracts.

Question 121

Define:

Acute Infection

Answer 121

An infection characterized by a rapid onset of symptoms and a relatively short duration, typically resolved once the pathogen is eliminated.

Question 122

Define:

Chronic Infection

Answer 122

An infection that begins acutely but persists over a long period, often with slow multiplication of the pathogen and progressive tissue damage.

Question 123

Define:

Latent Infection

Answer 123

An infection where the pathogen remains dormant within the host after an initial acute phase, not causing symptoms or being transmissible until reactivation.

Question 124

Define:

Prodromal Period

Answer 124

The phase of an infection characterized by mild or nonspecific symptoms that precede the onset of more severe symptoms.

Question 125

Define:

Disease Period

Answer 125

The phase of an infection marked by the peak of symptoms and tissue damage, defining the disease’s impact on the host.

Question 126

Define:

Recovery Period

Answer 126

The phase following the peak of an infection where symptoms decrease as the host’s defenses overcome the pathogen.

Question 127

Define:

Immune Complex

Answer 127

A combination of antigens and antibodies that can deposit in tissues, activating complement proteins and attracting phagocytes.

Question 128

Define:

Complement Proteins

Answer 128

Proteins in the blood that assist in the immune response by marking pathogens for destruction and attracting phagocytes.

Question 129

Define:

Flaccid Paralysis

Answer 129

A condition where muscles become weak and limp due to the inability to contract, often caused by toxins affecting neuromuscular junctions.

Question 130

Define:

Tetany

Answer 130

Sustained muscle contractions due to a disruption in normal nervous system function, often caused by certain toxins.

Question 131

Define:

Shingles

Answer 131

A reactivation of the varicella-zoster virus that causes a painful rash, usually along the path of a spinal nerve.

Question 132

Define:

Herpes Viruses

Answer 132

A group of viruses that can cause latent infections and reactivate later, such as varicella-zoster virus which causes both chickenpox and shingles.

Question 133

What is…

Microorganisms, including bacteria, viruses, fungi, and protozoa, that can live in and on the human body, influencing health in both positive and negative ways.

Answer 133

Microbes

Question 134

What is…

Microscopic organisms, including bacteria, fungi, viruses, protozoa, and algae, that can only be seen with a microscope. They make up a significant portion of Earth’s biomass.

Answer 134

Microbes

Question 135

What is…

Single-celled prokaryotic organisms that lack membrane-bound organelles. They are found in various environments, including the human body.

Answer 135

Bacteria

Question 136

What is…

Eukaryotic organisms that can exist as single cells or multicellular forms, such as molds and yeasts. They can produce toxins and antibiotics, like penicillin.

Answer 136

Fungi

Question 137

What is…

Acellular microbes that do not have all the components necessary for independent cell function and metabolism. They are not considered living organisms outside of a host.

Answer 137

Viruses

Question 138

What is…

Single-celled eukaryotic organisms that can live alone or in colonies, typically found in water. Examples include amoebas.

Answer 138

Protozoa

Question 139

What is…

Photosynthetic eukaryotic organisms that can be single-celled or multicellular, found mainly in aquatic environments.

Answer 139

Algae

Question 140

What is…

Cells with membrane-bound organelles, including a nucleus, Golgi apparatus, lysosomes, and mitochondria. Found in animals, plants, fungi, protozoa, and algae.

Answer 140

Eukaryotic cells

Question 141

What is…

Simpler cells that lack membrane-bound organelles and a nucleus. All bacteria are prokaryotes.

Answer 141

Prokaryotic cells

Question 142

What is…

Rod-shaped bacteria. The term is used in the names of rod-shaped bacterial species.

Answer 142

Bacilli

Question 143

What is…

Spherical-shaped bacteria. The term is used in the names of spherical bacterial species.

Answer 143

Cocci

Question 144

What is…

Spiral-shaped bacteria. This term is used for bacteria with a spiral shape.

Answer 144

Spirilla

Question 145

What is…

A specific type of spiral-shaped bacteria with a unique corkscrew motion.

Answer 145

Spirochete

Question 146

What is…

A comma-shaped or curved rod-shaped bacteria.

Answer 146

Vibrio

Question 147

What is…

The outer layers surrounding a bacterial cell, including the cell membrane and cell wall.

Answer 147

Cell envelope

Question 148

What is…

A glycoprotein consisting of protein and carbohydrate groups that forms a mesh-like layer in the bacterial cell wall, targeted by certain antibiotics.

Answer 148

Peptidoglycan

Question 149

What is…

An additional outer layer found in some bacteria, which can be sticky or slippery and aids in host colonization.

Answer 149

Capsule

Question 150

What is…

Hair-like structures on the surface of bacteria used for genetic material exchange and adherence to surfaces.

Answer 150

Pili

Question 151

What is…

A whip-like structure used by bacteria for locomotion and sometimes as a receptor for environmental changes.

Answer 151

Flagellum (Plural: Flagella)

Question 152

What is…

A region within a bacterial cell where the genetic material, a single circular DNA chromosome, is located.

Answer 152

Nucleoid

Question 153

What is…

The process of bacterial reproduction where a single bacterium divides into two identical daughter cells after DNA replication.

Answer 153

Binary fission

Question 154

What is…

Organisms that can only reproduce inside a host cell, relying on the host’s cellular machinery for replication.

Answer 154

Obligate parasites

Question 155

What is…

Viruses that have a protein coat called a capsid surrounding their genetic material but lack an outer lipid envelope.

Answer 155

Naked viruses

Question 156

What is…

Viruses that have a phospholipid bilayer derived from the host cell’s plasma membrane surrounding their capsid, which may contain embedded proteins for host cell attachment.

Answer 156

Enveloped viruses

Question 157

What is…

A protein coat surrounding the genetic material of a virus. It helps protect the viral genome and facilitates attachment to host cells.

Answer 157

Capsid

Question 158

What is…

An outer lipid bilayer surrounding some viruses, derived from the host cell’s membrane, which may contain viral proteins that assist in infection.

Answer 158

Envelope

Question 159

What is…

A type of viral infection that results in the destruction (lysis) of the host cell, releasing new viral particles.

Answer 159

Lytic infection

Question 160

What is…

A process by which cells take in external substances, such as viruses, by engulfing them in a vesicle.

Answer 160

Endocytosis

Question 161

What is…

The process by which an enveloped virus merges its lipid envelope with the host cell membrane to gain entry into the cell.

Answer 161

Fusion

Question 162

What is…

The process by which viruses exit the host cell, often involving the budding off of new viral particles from the cell membrane.

Answer 162

Exocytosis

Question 163

What is…

The virus responsible for COVID-19, characterized as an enveloped virus with spike proteins that facilitate attachment and entry into host cells.

Answer 163

SARS-CoV-2

Question 164

What is…

Surface proteins on some viruses, such as SARS-CoV-2, that enable the virus to bind to specific receptors on the host cell, facilitating infection.

Answer 164

Spike proteins

Question 165

What is…

A type of viral infection where the virus is released slowly from the host cell without killing it, leading to a prolonged presence in the host.

Answer 165

Chronic or persistent infection

Question 166

What is…

A condition in which a virus remains dormant inside a host cell without replicating, potentially becoming reactivated later.

Answer 166

Latent state

Question 167

What is…

A carbohydrate derivative of glucose that forms a tough, protective shell around fungal cells, similar to the exoskeletons of insects and crustaceans.

Answer 167

Chitin

Question 168

What is…

Single-celled fungi that reproduce by budding. They are oval-shaped and can be found in various environments.

Answer 168

Yeast

Question 169

What is…

A form of asexual reproduction in yeast where a new cell develops from an outgrowth or bud on the parent cell.

Answer 169

Budding

Question 170

What is…

Multicellular fungi that form a network of cells known as mycelium. They often appear as fuzzy or thread-like structures and are commonly seen on spoiled food.

Answer 170

Molds

Question 171

What is…

A network of fungal cells that forms the vegetative part of a fungus, such as mold. It helps in nutrient absorption and growth.

Answer 171

Mycelium

Question 172

What is…

A type of fungal infection commonly known as athlete’s foot, which affects the skin between the toes.

Answer 172

Tinea

Question 173

What is…

A fungal infection caused by Candida species, which can occur in areas such as the mouth (thrush) or other mucosal surfaces.

Answer 173

Candidiasis

Question 174

What is…

Individuals with weakened immune systems, such as those with HIV/AIDS, undergoing immunosuppressive treatments, or having chronic conditions like cancer or diabetes, who are more susceptible to severe fungal infections.

Answer 174

Immunocompromised

Question 175

What is…

A relationship between two organisms living together in close association. In the context of microbes and humans, it refers to how microbes interact with humans, either beneficially, neutrally, or harmfully.

Answer 175

Symbiosis

Question 176

What is…

Also known as resident flora, microbiota, or the microbiome. These are the microorganisms that regularly inhabit various parts of the human body and usually benefit the host by outcompeting harmful pathogens and assisting in various bodily functions.

Answer 176

Normal flora

Question 177

What is…

Microorganisms that temporarily inhabit the body but do not establish a permanent presence. They may be picked up from the environment and do not necessarily contribute to the body’s normal flora.

Answer 177

Transient microbes

Question 178

What is…

A type of symbiotic relationship where the microbe benefits from the interaction, while the host is unaffected (neither helped nor harmed).

Answer 178

Commensalism

Question 179

What is…

A symbiotic relationship where both the microbe and the host benefit from the interaction.

Answer 179

Mutualism

Question 180

What is…

A symbiotic relationship where the microbe benefits at the expense of the host, potentially causing harm or disease to the host.

Answer 180

Parasitism

Question 181

What is…

Refers to diseases that can be transmitted from one person to another. Infectious diseases are not always communicable, as some, like tooth decay, do not spread between individuals.

Answer 181

Communicable

Question 182

What is…

A type of bacteria found in the gastrointestinal tract and vagina. They metabolize glycogen to produce lactic acid, which maintains an acidic environment that inhibits the growth of harmful microbes.

Answer 182

Lactobacillus

Question 183

What is…

A bacterium commonly found in the large intestine. It helps with the metabolism of waste products and the production of essential vitamins, such as B-group vitamins and vitamin K, which are crucial for various bodily functions.

Answer 183

Escherichia coli (E. coli)

Question 184

What is…

A vitamin produced by intestinal bacteria, essential for normal blood clotting. Infants are often given a injection at birth to ensure proper clotting until their gut flora is established.

Answer 184

Vitamin K

Question 185

What is…

A fatty acid produced by intestinal microbes that serves as an energy source for epithelial cells in the large intestine. It supports cell health and reduces the risk of colon cancer by enhancing blood flow and immune function.

Answer 185

Butyrate

Question 186

What is…

The body’s initial, non-specific defense mechanisms that respond quickly to pathogens. It includes physical barriers like skin and mucous membranes, as well as various immune cells and proteins.

Answer 186

Innate immune defenses

Question 187

What is…

The part of the immune system that develops a specific response to pathogens and improves its response with each exposure. It involves specialized cells and antibodies.

Answer 187

Adaptive immune defenses

Question 188

What is…

An objective change in the body that can be observed or measured by a healthcare provider, such as a fever.

Answer 188

Sign

Question 189

What is…

A subjective experience reported by the patient, such as pain or fatigue, which cannot be directly measured but indicates an underlying condition.

Answer 189

Symptom

Question 190

What is…

An infection or disease that does not produce noticeable symptoms, often because the immune system has successfully contained the pathogen.

Answer 190

Subclinical disease

Question 191

What is…

The capacity of a microbe to cause disease. It measures how harmful the microbe is and affects the severity of the disease it can cause.

Answer 191

Virulence

Question 192

What is…

The minimum number of pathogens required to cause an infection. A lower infectious dose indicates higher virulence.

Answer 192

Infectious dose

Question 193

What is…

Microbes that cause disease in individuals with normal immune defenses. Examples include viruses like the measles virus and bacteria like Neisseria gonorrhoeae.

Answer 193

Conventional pathogens

Question 194

What is…

Microbes that usually do not cause disease in healthy individuals but can lead to infections when the host’s immune defenses are compromised or when they colonize an unusual body site.

Answer 194

Opportunistic pathogens

Question 195

What is…

A disruption in the normal balance of microbes, allowing opportunistic pathogens to overgrow. For instance, the reduction of Lactobacillus bacteria can lead to the overgrowth of Candida albicans.

Answer 195

Ecological imbalance

Question 196

What is…

When normal flora microbes move to a part of the body where they are not typically found, potentially causing infections. For example, E. coli from the large intestine causing a urinary tract infection.

Answer 196

Relocation

Question 197

What is…

When the immune system or physical barriers are weakened, making the host more susceptible to infections. Factors include preexisting conditions, age, and compromised immune systems.

Answer 197

Compromised host defenses

Question 198

What is…

A genus of fungus found in various environments, such as damp hay, which can cause respiratory infections in immunocompromised individuals.

Answer 198

Aspergillus

Question 199

What is…What is…

The initial reaction of the immune system to a pathogen, aimed at eliminating it and leading to recovery.

Answer 199

Primary immune response

Question 200

What is…

A faster and more effective immune response that occurs upon subsequent exposure to a pathogen, often preventing disease or reducing its severity.

Answer 200

Secondary immune response

Question 201

What is…

The site through which a pathogen enters the body. Different pathogens may have preferred entry points for effective infection.

Answer 201

Portal of Entry

Question 202

What is…

Physical barriers of the body that act as the first line of defense against pathogens. Pathogens may enter through openings in the skin or mucous membranes.

Answer 202

Skin and Mucous Membranes

Question 203

What is…

A sticky substance secreted by some bacteria that helps them adhere to body surfaces and can contribute to the formation of biofilms, such as dental plaque.

Answer 203

Glycocalyx

Question 204

What is…

The process by which viruses bind to specific molecules on the surface of target cells to facilitate infection.

Answer 204

Viral Attachment

Question 205

What is…

Microbes that obtain nutrients from extracellular fluids and do not need to enter host cells to cause disease.

Answer 205

Extracellular pathogens

Question 206

What is…

Microbes that obtain nutrients from within host cells, causing disease by infecting and replicating inside these cells.

Answer 206

Intracellular pathogens

Question 207

What is…

Traits or abilities of a pathogen that enable it to evade host defenses, cause damage, or persist within the host.

Answer 207

Virulence factors

Question 208

What is…

Physical and chemical defenses of the body, such as the skin and mucous membranes, that prevent microbial entry and infection.

Answer 208

Surface Barriers

Question 209

What is…

A mechanism by which pathogens alter their surface proteins to evade recognition by the immune system, leading to ongoing or repeated infections.

Answer 209

Antigenic Variation

Question 210

What is…

Direct damage caused by pathogens, particularly viruses, which leads to the death of host cells.

Answer 210

Cytopathic Effects

Question 211

What is…

Formation of excess fibrous connective tissue in response to chronic inflammation, leading to scarring and loss of function.

Answer 211

Fibrosis

Question 212

What is…

The route through which a pathogen exits the host’s body to spread to new hosts, commonly through respiratory or digestive tracts.

Answer 212

Portal of Exit

Question 213

What is…

An infection characterized by a rapid onset of symptoms and a relatively short duration, typically resolved once the pathogen is eliminated.

Answer 213

Acute Infection

Question 214

What is…

An infection that begins acutely but persists over a long period, often with slow multiplication of the pathogen and progressive tissue damage.

Answer 214

Chronic Infection

Question 215

What is…

An infection where the pathogen remains dormant within the host after an initial acute phase, not causing symptoms or being transmissible until reactivation.

Answer 215

Latent Infection

Question 216

What is…

The phase of an infection characterized by mild or nonspecific symptoms that precede the onset of more severe symptoms.

Answer 216

Prodromal Period

Question 217

What is…

The phase of an infection marked by the peak of symptoms and tissue damage, defining the disease’s impact on the host.

Answer 217

Disease Period

Question 218

What is…

The phase following the peak of an infection where symptoms decrease as the host’s defenses overcome the pathogen.

Answer 218

Recovery Period

Question 219

What is…

A combination of antigens and antibodies that can deposit in tissues, activating complement proteins and attracting phagocytes.

Answer 219

Immune Complex

Question 220

What is…

Proteins in the blood that assist in the immune response by marking pathogens for destruction and attracting phagocytes.

Answer 220

Complement Proteins

Question 221

What is…

A condition where muscles become weak and limp due to the inability to contract, often caused by toxins affecting neuromuscular junctions.

Answer 221

Flaccid Paralysis

Question 222

What is…

Sustained muscle contractions due to a disruption in normal nervous system function, often caused by certain toxins.

Answer 222

Tetany

Question 223

What is…

A reactivation of the varicella-zoster virus that causes a painful rash, usually along the path of a spinal nerve.

Answer 223

Shingles

Question 224

What is…

A group of viruses that can cause latent infections and reactivate later, such as varicella-zoster virus which causes both chickenpox and shingles.

Answer 224

Herpes Viruses

Question 225

What role do microbes play in our lives?

Answer 225

Microbes influence our health by having both beneficial and harmful effects. They are crucial for understanding infection processes and disease prevention in clinical settings.

Question 226

What are microbes?

Answer 226

Microbes are microscopic organisms, including bacteria, fungi, and viruses, that can only be seen with a microscope.

Question 227

What percentage of Earth’s biomass is made up of microbes?

Answer 227

Microbes make up 90% of the Earth’s biomass.

Question 228

What types of organisms are included in the term “microbes”?

Answer 228

Microbes include bacteria, fungi, protozoa, algae, and viruses.

Question 229

Why are viruses not considered living organisms when outside a host?

Answer 229

Viruses lack the components necessary for cell function and independent metabolism.

Question 230

What distinguishes eukaryotic cells from prokaryotic cells?

Answer 230

Eukaryotic cells have membrane-bound organelles and a nucleus, while prokaryotic cells do not.

Question 231

Which cells are considered prokaryotic?

Answer 231

All bacteria are prokaryotic cells.

Question 232

What is the size range of typical bacteria?

Answer 232

Bacteria range from 1 to 5 micrometers in diameter.

Question 233

How do viruses compare in size to bacteria?

Answer 233

Viruses are much smaller than bacteria, falling in the nanometer range and requiring an electron microscope to be seen.

Question 234

What system is used to name microbes?

Answer 234

The binomial nomenclature system, which includes a genus name and a species name.

Question 235

What is the scientific name for “golden staph”?

Answer 235

The scientific name is Staphylococcus aureus.

Question 236

What shape is indicated by the term “bacilli”?

Answer 236

“Bacilli” refers to rod-shaped bacteria.

Question 237

What does the term “cocci” describe?

Answer 237

“Cocci” describes spherical bacteria.

Question 238

How do bacteria obtain nutrients?

Answer 238

Bacteria release enzymes to digest organic material extracellularly and then absorb the nutrients in dissolved form.

Question 239

What is the cell envelope of a bacterium composed of?

Answer 239

The cell envelope includes the cell membrane (phospholipid bilayer) and, in many cases, a cell wall made of peptidoglycan.

Question 240

Why are antibiotics like penicillin effective against bacteria?

Answer 240

Penicillin targets peptidoglycan in the bacterial cell wall, disrupting cell wall formation and leading to bacterial death.

Question 241

What is the function of a bacterial capsule?

Answer 241

A capsule helps bacteria adhere to hosts and can be sticky or slippery.

Question 242

What is the role of pili in bacteria?

Answer 242

Pili are used for the exchange of genetic material between bacteria.

Question 243

What is the function of a bacterial flagellum?

Answer 243

A flagellum aids in locomotion and can function as a receptor for detecting external chemicals or temperature changes.

Question 244

Where is bacterial genetic material located?

Answer 244

The genetic material is located in the nucleoid, a region containing a single circular chromosome.

Question 245

What is the process of bacterial reproduction called?

Answer 245

Bacterial reproduction is called binary fission.

Question 246

How quickly can E. coli reproduce under optimal conditions?

Answer 246

E. coli can divide every 20 minutes under optimal conditions.

Question 247

What are viruses made of?

Answer 247

Viruses are packets of genetic material, either DNA or RNA, surrounded by a protein coat called a capsid.

Question 248

What distinguishes a naked virus from an enveloped virus?

Answer 248

A naked virus has only a protein capsid surrounding its genetic material, while an enveloped virus has an additional outer phospholipid bilayer derived from the host cell’s plasma membrane.

Question 249

Why are viruses considered obligate parasites?

Answer 249

Viruses are obligate parasites because they must infect a host cell to reproduce, as they lack the necessary machinery to reproduce on their own.

Question 250

How do naked viruses typically enter a host cell?

Answer 250

Naked viruses usually enter a host cell via endocytosis.

Question 251

How do enveloped viruses typically enter a host cell?

Answer 251

Enveloped viruses can fuse their envelope with the host cell membrane to enter more easily.

Question 252

What is a lytic infection?

Answer 252

A lytic infection is one where the virus attaches to the host cell, enters, uses the host’s machinery to replicate, and eventually causes the cell to lyse and die, releasing new viral particles.

Question 253

What is an example of a virus that causes a lytic infection?

Answer 253

SARS-CoV-2, which causes COVID-19, is an example of a virus that causes a lytic infection.

Question 254

How does SARS-CoV-2 facilitate its entry into host cells?

Answer 254

SARS-CoV-2 uses spike proteins on its envelope to bind to receptors on epithelial cells, facilitating fusion with the host cell membrane.

Question 255

What happens during the maturation of enveloped viruses?

Answer 255

Enveloped viruses assemble their nucleic acids and capsid proteins inside the host cell, then bud off from the host cell membrane, taking part of the plasma membrane with them to form their envelope.

Question 256

What are the four possible outcomes of a viral infection?

Answer 256

Lytic infection
Chronic or persistent infection
Latent infection
Transformation of host cells into tumor cells

Question 257

What is a chronic or persistent viral infection?

Answer 257

A chronic or persistent infection occurs when the virus is released slowly from the host cell without killing it, and the infection can last for months, years, or even a lifetime.

Question 258

What characterizes a latent viral infection?

Answer 258

In a latent infection, the virus remains dormant inside the host cell without replicating or causing damage, and it can be reactivated later to cause a lytic infection.

Question 259

What is an example of a virus that can transform normal cells into tumor cells?

Answer 259

Papillomavirus is an example that can cause benign tumors like skin warts or malignant tumors like cervical cancer.

Question 260

What is the primary component of a fungal cell wall?

Answer 260

The primary component of a fungal cell wall is chitin.

Question 261

How do yeast cells reproduce?

Answer 261

Yeast cells reproduce by budding.

Question 262

What are molds, and how do they differ from yeast?

Answer 262

Molds are multicellular fungi that form a network of cells called mycelium, whereas yeast are single-celled fungi.

Question 263

What types of infections can fungi cause?

Answer 263

Fungi can cause superficial infections like athlete’s foot and thrush, as well as more serious infections in immunocompromised individuals.

Question 264

Which organization has prioritized fungal pathogens and why?

Answer 264

The World Health Organization (WHO) has prioritized fungal pathogens due to their increasing incidence and the limited treatment options available.

Question 265

What are the three types of relationships between humans and microbes?

Answer 265

Commensalism
Mutualism
Parasitism

Question 266

What is commensalism?

Answer 266

In commensalism, the microbe benefits from the relationship without affecting the host.

Question 267

What is mutualism?

Answer 267

In mutualism, both the microbe and the host benefit from the relationship.

Question 268

What is parasitism?

Answer 268

In parasitism, the microbe benefits at the expense of the host, potentially causing harm.

Question 269

What does the term “normal flora” refer to?

Answer 269

Normal flora refers to the variety of microbes that establish a population on body surfaces, such as the skin and gastrointestinal tract.

Question 270

How are microbes colonized on the body?

Answer 270

Microbes colonize the body surfaces by establishing a population and growing there after birth, coming from sources like the maternal vagina, diet, and the environment.

Question 271

Where are normal flora typically found on the skin?

Answer 271

Normal flora are usually found in warm, moist areas of the skin, such as the groin and armpits.

Question 272

What role do commercial deodorants play in managing body odor?

Answer 272

Deodorants work by inhibiting microbial metabolic activity or by keeping the skin dry to prevent microbial growth and body odor.

Question 273

How does the digestive tract support microbial growth?

Answer 273

The digestive tract is warm, moist, and filled with food sources, making it an ideal environment for microbes.

Question 274

What is the microbial density like in the mouth compared to the stomach and intestines?

Answer 274

The mouth has about 100 billion bacteria per gram of wet tissue, the stomach has fewer microbes due to low pH, and the number of microbes increases in the small and large intestines.

Question 275

What are some benefits of microbes in the large intestine?

Answer 275

Microbes in the large intestine help digest certain fibers, produce vitamins B and K, and create fatty acids that are used for energy.

Question 276

Why are the bronchi and lungs relatively free of microbes?

Answer 276

The bronchi and lungs are relatively free of microbes due to the mucociliary escalator and the presence of macrophages.

Question 277

Are the upper regions of the urinary tract sterile?

Answer 277

Yes, the upper regions of the urinary tract, including the kidneys, ureters, and bladder, are typically sterile.

Question 278

What types of microbes are found in the urethra?

Answer 278

The urethra, which connects the bladder to the outside, can contain microbes in both males and females, but the number is low due to the flushing action of urine.

Question 279

Where are microbes found in the reproductive tracts?

Answer 279

In females, microbes are commonly found in the vagina, while the ovaries and higher areas of the reproductive tract are sterile. In males, the urethra contains some microbes.

Question 280

What is the proportion of microbial cells to human cells on our body surfaces?

Answer 280

There are about 10 times as many microbial cells on our body surfaces as there are human cells.

Question 281

How do normal flora maintain ecological balance with the host?

Answer 281

Normal flora live, reproduce, and feed in place on body surfaces, maintaining a stable ecosystem with relatively constant numbers and types of microbes.

Question 282

How can the composition of normal flora change over time?

Answer 282

The composition can change due to factors like the emergence of a baby’s teeth creating a new ecological niche.

Question 283

What is commensalism in the context of normal flora?

Answer 283

In commensalism, one partner benefits (the microbe) while the other (the host) remains unaffected.

Question 284

How does mutualism benefit both the normal flora and the host?

Answer 284

In mutualism, both the microbe and the host benefit, such as when normal flora prevent pathogens from colonizing or produce beneficial compounds like vitamins.

Question 285

How does Lactobacillus bacteria benefit the host in the vagina?

Answer 285

Lactobacillus bacteria metabolize glycogen into lactic acid, which helps maintain an acidic environment and prevents overgrowth of harmful microbes.

Question 286

What is the role of E. coli in the large intestine?

Answer 286

E. coli helps metabolize waste products and produce essential vitamins like B-group vitamins and vitamin K.

Question 287

Why are babies given a vitamin K injection at birth?

Answer 287

Babies are given vitamin K injections because their gut flora are not fully developed yet to produce sufficient vitamin K for normal blood clotting.

Question 288

What is butyrate and why is it important?

Answer 288

Butyrate is a fatty acid produced by intestinal microbes that serves as an energy source for epithelial cells in the large intestine and helps reduce the risk of colon cancer.

Question 289

What is parasitism in relation to microbes?

Answer 289

Parasitism is a relationship where one partner (the parasite) benefits at the expense of the host, causing tissue damage and activating host defenses.

Question 290

What type of pathogens are also considered parasites?

Answer 290

Pathogens that cause infectious diseases and use the host as a resource for growth are also considered parasites.

Question 291

What must a microbe do to establish an infection?

Answer 291

It must attach to a body surface, colonize that surface by multiplying while avoiding host defenses, and then invade deeper tissues.

Question 292

What is the difference between a sign and a symptom of disease?

Answer 292

A sign is an objective change that can be observed or measured, such as a fever, while a symptom is subjective and relates to the patient’s experience, like a headache.

Question 293

What is the primary cause of tissue damage in infectious disease?

Answer 293

Tissue damage is primarily due to the activities of the pathogen, although host defenses may also contribute.

Question 294

What happens during a primary immune response?

Answer 294

The primary immune response is triggered by an infection, aiming to combat the pathogen and lead to recovery.

Question 295

What is asymptomatic disease?

Answer 295

Asymptomatic disease occurs when an infection is present but shows no symptoms.

Question 296

What is subclinical disease?

Answer 296

Subclinical disease refers to an infection with very minor symptoms.

Question 297

What factors influence whether an infectious disease occurs and is transmitted?

Answer 297

Three factors include the pathogen’s pathogenicity, the host’s susceptibility, and the environment’s suitability for the microbe’s survival and transmission.

Question 298

What is virulence?

Answer 298

Virulence is a measure of how harmful a microbe is, with more virulent microbes causing more severe disease.

Question 299

What is an infectious dose?

Answer 299

The infectious dose is the minimum number of pathogens required to cause disease.

Question 300

Name a highly virulent pathogen and its impact.

Answer 300

Smallpox has killed approximately 300 million people in the 20th century alone.

Question 301

How can preexisting poor health affect susceptibility to infection?

Answer 301

Conditions like malnutrition or diabetes can impair immune function and increase the risk of infection.

Question 302

How does immune status affect susceptibility to infection?

Answer 302

Vaccination status and treatments that compromise immune defenses can significantly affect susceptibility.

Question 303

Why are extremities of age a risk factor for infection?

Answer 303

Young babies have immature immune systems, and the elderly may have waning immune defenses, both affecting their ability to combat pathogens.

Question 304

What role do environmental conditions play in infection risk?

Answer 304

Environmental conditions affect individual health, the reservoir of infection, and how easily pathogens are transmitted, influencing the likelihood of infection.

Question 305

What are conventional pathogens?

Answer 305

Conventional pathogens are microbes that cause disease in individuals with normal defenses, such as the measles virus and Neisseria bacteria.

Question 306

What are opportunistic pathogens?

Answer 306

Opportunistic pathogens are microbes that usually do not cause disease in healthy individuals but can do so under certain conditions.

Question 307

What is an example of an opportunistic infection caused by ecological imbalance?

Answer 307

Candidiasis or thrush caused by Candida albicans overgrowing when normal flora like Lactobacillus are reduced.

Question 308

How can relocation of normal flora lead to opportunistic infection?

Answer 308

Normal flora can cause infections if they move to areas of the body where they are normally excluded, such as E. coli causing a urinary tract infection.

Question 309

What is an example of an opportunistic infection due to compromised host defenses?

Answer 309

Pneumonia caused by Streptococcus bacteria in individuals with impaired mucociliary escalator function or severe immunocompromised patients, like those with AIDS.

Question 310

What is an opportunistic infection?

Answer 310

An opportunistic infection is caused by microbes that typically have low pathogenicity but can cause disease in individuals with reduced immune defenses.

Question 311

Give an example of a fungus that can cause opportunistic infections in compromised individuals.

Answer 311

Aspergillus, a common fungus found in damp hay and straw, can lead to chronic respiratory infections in compromised individuals.

Question 312

What are the two possible outcomes when a microbe attaches to the body?

Answer 312

The microbe may be quickly dislodged, resulting in a transient association.
The microbe may multiply and colonize the body surface.

Question 313

What happens when a microbe establishes a stable relationship with the host?

Answer 313

It can become part of the normal flora, where the relationship is commensal or mutualistic, and the host is not harmed or may benefit.

Question 314

What is the difference between an asymptomatic and a subclinical infection?

Answer 314

An asymptomatic infection has no symptoms or tissue damage, while a subclinical infection has minor symptoms and tissue damage.

Question 315

List the steps involved in an infectious disease.

Answer 315

Entry
Multiplication
Damage
Exit
Evade Host Defenses

Question 316

What is the portal of entry for most pathogens?

Answer 316

The portal of entry is the site where a pathogen enters the body, such as the respiratory tract or gastrointestinal tract.

Question 317

How can pathogens enter the body through the skin?

Answer 317

Pathogens can enter through openings like hair follicles or sweat glands, or through compromised skin due to injury or puncture.

Question 318

What is the role of adhesions in pathogen attachment?

Answer 318

Adhesions are surface molecules that help pathogens bind to receptors on target cells.

Question 319

What is glycocalyx and how does it assist bacteria?

Answer 319

Glycocalyx is a sticky substance secreted by some bacteria that cements them to body surfaces, forming biofilms like dental plaque.

Question 320

Give an example of a pathogen that adheres to specific surface molecules on target cells.

Answer 320

HIV adheres to CD4 and CCR5 molecules on helper T cells and macrophages.

Question 321

Why do pathogens need to multiply to a critical population size?

Answer 321

To cause disease, pathogens need to reach a critical population size during the incubation period to overcome host defenses and spread throughout the body.

Question 322

What distinguishes extracellular pathogens from intracellular pathogens?

Answer 322

Extracellular pathogens obtain nutrients from extracellular fluids, while intracellular pathogens obtain nutrients from inside host cells.

Question 323

How do some pathogens overcome host defenses?

Answer 323

By penetrating barriers, avoiding or inactivating host defenses, or producing virulence factors.

Question 324

What is the role of collagenase produced by Streptococcus bacteria?

Answer 324

Collagenase breaks down collagen in the skin, allowing bacteria to invade deeper tissues.

Question 325

How does Bordetella pertussis contribute to disease development?

Answer 325

It secretes toxins that inactivate the mucociliary escalator, allowing the bacteria to reach deeper lung tissue.

Question 326

How do some bacteria resist phagocytes?

Answer 326

By having slippery capsules or glycocalyx that prevent phagocytes from adhering and engulfing them, or by producing leukocidins that kill phagocytes.

Question 327

What is the function of IgA proteases produced by some pathogens?

Answer 327

IgA proteases destroy IgA antibodies, preventing them from neutralizing microbes and allowing infection to occur.

Question 328

What is antigenic variation and how does it affect pathogen recognition?

Answer 328

Antigenic variation is the process by which pathogens alter their surface molecules, making them unrecognizable to previously generated antibodies and evading immune responses.

Question 329

Why can people get COVID-19 multiple times?

Answer 329

Due to antigenic variation in the spike protein of coronaviruses, antibodies from a primary infection may not effectively block subsequent infections.

Question 330

How do mutations in the spike protein of coronaviruses affect vaccine effectiveness?

Answer 330

Mutations can impact how the virus binds to and enters cells, potentially reducing the effectiveness of vaccines and treatments.

Question 331

What type of damage can pathogens cause directly?

Answer 331

Pathogens can cause damage directly through the secretion of enzymes or toxins, killing host cells, or consuming host resources.

Question 332

How do toxins produced by pathogens cause harm?

Answer 332

Toxins can kill phagocytes, induce high fevers, affect the cardiovascular system leading to shock, or cause diarrhea. They can sometimes be a major factor in the host’s death.

Question 333

What is an example of a toxin that affects the nervous system?

Answer 333

Tetanus toxin affects the central nervous system, causing sustained muscle contractions and potentially leading to respiratory failure.

Question 334

What does botulinum toxin do to the neuromuscular junction?

Answer 334

Botulinum toxin blocks the release of acetylcholine at the neuromuscular junction, causing flaccid paralysis.

Question 335

What are cytopathic effects?

Answer 335

Cytopathic effects refer to direct damage caused by a pathogen, leading to the death of host cells.

Question 336

Which virus is known for causing poliomyelitis and its associated effects?

Answer 336

Poliovirus causes poliomyelitis, leading to damage in corticospinal pathways and resulting in flaccid paralysis of the limbs.

Question 337

How do bacteria obtain essential nutrients from host cells?

Answer 337

Some bacteria, like those needing iron stored in the liver, kill host cells to access the nutrients they need.

Question 338

What is a cytotoxin and how does it affect host cells?

Answer 338

A cytotoxin damages cell membranes or other critical cellular components, leading to the destruction of host cells.

Question 339

What role does inflammation play in tissue damage?

Answer 339

Inflammation can cause swelling, which might compress and abrade tissues, and potentially lead to severe conditions like airway obstruction or brain herniation.

Question 340

How can extracellular release of digestive enzymes cause tissue damage?

Answer 340

Immune complexes or large parasites might lead to the release of enzymes from phagocytes, which can damage surrounding tissues.

Question 341

What is an example of a condition resulting from chronic inflammation leading to scarring?

Answer 341

Pelvic inflammatory disease caused by long-term infection can lead to scarring in the reproductive organs and potentially result in infertility.

Question 342

How do pathogens typically exit the body to spread to new hosts?

Answer 342

Pathogens often exit through the respiratory or digestive tracts, for example, via coughing or diarrhea.

Question 343

What are the four phases of an acute infection?

Answer 343

The four phases are the incubation period, the prodromal period, the disease period, and the recovery period.

Question 344

What happens during the incubation period of an infection?

Answer 344

The incubation period is the time between exposure to the pathogen and the onset of symptoms, influenced by factors such as pathogen virulence and host resistance.

Question 345

What characterizes the prodromal period?

Answer 345

The prodromal period is marked by mild or nonspecific symptoms such as headache or fatigue, with the pathogen continuing to multiply.

Question 346

During which phase of an infection are specific signs and symptoms most prominent?

Answer 346

The disease period is when specific signs and symptoms of the disease are most prominent.

Question 347

What occurs during the recovery period of an infection?

Answer 347

During the recovery period, the number of pathogens decreases, signs and symptoms reduce, and eventually, the pathogen may no longer be detectable.

Question 348

Can a patient transmit a pathogen during the incubation period?

Answer 348

Yes, a patient can transmit the pathogen during the incubation period, even before symptoms appear.

Question 349

What is the initial phase of a chronic infection like?

Answer 349

A chronic infection begins with an acute symptomatic disease, but the pathogen is not completely eliminated and continues to multiply slowly.

Question 350

How does a chronic infection differ from an acute infection in terms of pathogen multiplication?

Answer 350

In a chronic infection, the pathogen continues to multiply slowly over time, whereas in an acute infection, the pathogen typically causes rapid and severe symptoms but is usually eliminated quickly.

Question 351

What happens to the pathogen numbers in a chronic infection over time?

Answer 351

The pathogen numbers slowly increase over time, and there may be subsequent acute periods where symptoms reappear.

Question 352

Can a host with a chronic infection still transmit the pathogen?

Answer 352

Yes, even if the host appears healthy, they can still transmit the pathogen because the pathogen continues to multiply, albeit slowly.

Question 353

Give an example of a chronic infection and its potential long-term effects.

Answer 353

Hepatitis B is a chronic infection that can lead to liver damage, scar tissue formation, liver failure, and potentially liver cancer.

Question 354

How do latent infections begin and what happens to the pathogen after the initial acute phase?

Answer 354

Latent infections start with an acute symptomatic disease, but the pathogen becomes dormant after the initial phase, hiding within body cells and not multiplying.

Question 355

What is the state of the pathogen during the latent period of an infection?

Answer 355

During the latent period, the pathogen remains dormant, does not multiply, and cannot be transmitted. The host remains asymptomatic.

Question 356

How does reactivation of a latent infection differ from the initial infection?

Answer 356

Reactivation leads to a new episode of acute disease, and the symptoms may differ from those of the initial infection.

Question 357

What is a classic example of a latent infection and how does it manifest later?

Answer 357

Herpes viruses are a classic example. Chickenpox caused by varicella-zoster virus can later reactivate as shingles, presenting with a rash following the distribution of a spinal nerve.

Question 358

What is the duration and characteristic of an acute infection?

Answer 358

Acute infections are short-term with present symptoms and generally result in rapid recovery. The pathogen is transmissible as long as it is multiplying.

Question 359

How does a chronic infection typically progress after the initial acute phase?

Answer 359

A chronic infection progresses with the pathogen continuing to multiply slowly, causing progressive tissue damage, and may lead to periodic acute episodes.

Question 360

Can a latent infection ever become transmissible again?

Answer 360

Yes, when a latent infection reactivates, the pathogen can begin multiplying again and may become transmissible.

Question 361

Provide an example of an acute infection and its duration.

Answer 361

Influenza virus is an example of an acute infection, which is typically short-term with rapid onset and recovery.

Question 362

What is the primary difference between chronic and latent infections in terms of pathogen activity?

Answer 362

Chronic infections involve ongoing pathogen multiplication and tissue damage, while latent infections involve a dormant pathogen that does not multiply or cause damage during the latent period.

Question 363

How does the transmissibility of a chronic infection compare to that of a latent infection?

Answer 363

A chronic infection remains transmissible as the pathogen continues to multiply, while a latent infection is not transmissible during the dormant phase but can become transmissible if reactivated.

Question 364

Which of the following is a major structural feature of bacteria?
a) Nucleus
b) Cell wall
c) Chloroplast
d) Mitochondria

Answer 364

b) Cell wall

Question 365

What structure is unique to fungi compared to bacteria and viruses?
a) Capsule
b) Cell membrane
c) Chitin cell wall
d) RNA genome

Answer 365

c) Chitin cell wall

Question 366

Which of the following is a characteristic of viruses?
a) Cellular structure
b) Ability to reproduce independently
c) DNA or RNA genome
d) Cell wall

Answer 366

c) DNA or RNA genome

Question 367

Which type of microbe is characterized by having a chitinous cell wall and is eukaryotic?
a) Bacteria
b) Virus
c) Fungi
d) Protozoa

Answer 367

c) Fungi

Question 368

What is one of the three main types of microbes humans interact with?
a) Bacteria
b) Rocks
c) Plants
d) Metals

Answer 368

a) Bacteria

Question 369

Which relationship describes a microbe that benefits at the expense of the host?
a) Mutualism
b) Commensalism
c) Parasitism
d) Synergism

Answer 369

c) Parasitism

Question 370

Which term describes a pathogen that only causes disease when the host’s defenses are compromised?
a) Conventional pathogen
b) Opportunistic pathogen
c) Primary pathogen
d) Secondary pathogen

Answer 370

b) Opportunistic pathogen

Question 371

What is a key factor that determines whether an infection will occur?
a) Pathogen’s color
b) Pathogen’s resistance to sunlight
c) Host’s immune status
d) Host’s dietary habits

Answer 371

c) Host’s immune status

Question 372

Which of the following is a step in the infectious disease process?
a) Symptom resolution
b) Pathogen exit
c) Pathogen replication
d) None of the above

Answer 372

c) Pathogen replication

Question 373

What is the first step in the infectious disease process?
a) Infection
b) Incubation
c) Exposure
d) Recovery

Answer 373

c) Exposure

Question 374

During which phase of an acute infection do symptoms become most severe?
a) Incubation period
b) Prodromal period
c) Disease period
d) Recovery period

Answer 374

c) Disease period

Question 375

Which type of infection is characterized by an initial acute disease followed by a long-term, slowly progressing infection?
a) Acute infection
b) Chronic infection
c) Latent infection
d) Subclinical infection

Answer 375

b) Chronic infection

Question 376

What happens during the latent period of an infection?
a) The pathogen multiplies rapidly
b) The pathogen is dormant and not multiplying
c) Symptoms are severe and pronounced
d) The host’s immune system is compromised

Answer 376

b) The pathogen is dormant and not multiplying

Question 377

What is a common outcome of a chronic infection?
a) Rapid recovery
b) Persistent mild symptoms
c) Sudden severe symptoms
d) Immediate resolution

Answer 377

b) Persistent mild symptoms

Question 378

In which type of infection does the pathogen remain dormant within body cells for years before reactivation?
a) Acute infection
b) Chronic infection
c) Latent infection
d) Secondary infection

Answer 378

c) Latent infection

Question 379

Which example represents a latent infection?
a) Influenza
b) Chickenpox leading to shingles
c) Hepatitis B
d) Tuberculosis

Answer 379

b) Chickenpox leading to shingles

Question 380

What is the main feature of an acute infection?
a) Long-term persistence with progressive damage
b) Periodic reactivation of symptoms
c) Short-term illness with rapid onset and recovery
d) Persistent mild symptoms over many years

Answer 380

c) Short-term illness with rapid onset and recovery

Question 381

Which of the following infections is classified as chronic?
a) Common cold
b) Measles
c) Hepatitis C
d) Herpes simplex

Answer 381

c) Hepatitis C

Question 382

What phase follows the initial acute symptoms in a chronic infection?
a) Immediate recovery
b) Latent phase
c) Gradual resolution
d) Long-term persistence

Answer 382

d) Long-term persistence

Question 383

During which phase of an acute infection are pathogens actively multiplying and causing significant damage?
a) Incubation period
b) Prodromal period
c) Disease period
d) Recovery period

Answer 383

c) Disease period

Question 384

What are the 3 types of relationship that exist between humans and microbes?

Answer 384

Commensal
Mutualistic
Parasitic

Question 385

What 3 conditions determine if an infection will occur?

Answer 385

1. Susceptibility of the host
2. Virulence of the pathogen
3. How conducive the environment is to infection

Question 386

What are the 4 stages of an acute infection?

Answer 386

Incubation
Prodromal
Disease
Recovery

Question 387

List 3 types of infection.

Answer 387

Acute
Chronic
Latent

Question 388

Where are the normal flora found?

Answer 388

Skin - mainly in warmer, damper areas
Digestive tract - mouth - lots! Throughout tract but few in stomach (low pH)
Respiratory tract - upper tract only - due to mucociliary escalator
Urinary tract - Lower tract only (urethra)
Reproductive tract - lower tract only (urethra and vagina)

Question 389

2. Summarise the benefits both humans and the normal flora receive from our symbiotic relationship.

Answer 389

Normal flora receive:
* Living space
* Nutrition

Human hosts benefit from:
* Presence of normal flora prevents pathogens from colonising body surfaces
* Products of normal flora can make the body surface inhospitable to pathogens, e.g. acidic environment produced by Lactobaccillus in the vagina
* Normal flora may produce useful molecules, e.g. vitamins B and K, butyrate

Question 390

3. Identify three (3) ways the body’s normal flora can cause an opportunistic infection and disease, and give an example of each.

Answer 390

1. Ecological balance us upset – allowing an overgrowth of a species normally present in small numbers e.g. Candida albicans in the vagina causing candidiasis (thrush)
2. Normal flora relocated to body areas they are normally excluded from e.g. E. coli from the large intestine moves into the urethra causing a UTI
3. Host defences (innate and/or adaptive) are compromised e.g. immunodeficiency disease (HIV), immunosuppression (chemotherapy)

Question 391

4. Fiona McDonald is a 70-year old woman who had a fall and fractured the neck of her right femur. During her recovery, she has an in-dwelling urinary catheter. If all of the appropriate nursing procedures are followed, will there be an infection risk associated with this line? Explain your answer.

Answer 391

Yes, there will be a risk of infection
The urinary catheter compromises the first line of defence (physical barriers)
* provides a portal of entry
* allows normal flora to penetrate deeper tissues from which they are normally excluded

Question 392

5. Successful infection of a host requires that the pathogen is able to enter the host, attach to the appropriate target tissue and evade host defences long enough to multiple and spread within the body.

a. Identify two (2) strategies that a pathogen might use to attach to target surfaces or cells.

Answer 392

Adhesins → molecules that attach to body surfaces/target cells
Sticky capsule (glycocalyx) → stick to body surfaces
Receptors → pathogen can bind specific surface molecules on target cell membranes, e.g. HIV, influenza

Question 393

What strategies to overcome innate defences do pathogen use to avoid physical barriers?

Answer 393

• Enzymes that break down surface barriers/connective tissue
• Toxins that inactivate the mucociliary escalator

Question 394

What strategies to overcome innate defences do pathogen use to resist phagocytes?

Answer 394

• Slippery capsule
• Toxins that kill phagocytes
• Enzymes that inactivate lysosomal enzymes

Question 395

What strategies to overcome adaptive defences do pathogen use to degrade antibodies?

Answer 395

Enzymes that destroy IgA antibodies in mucus

Question 396

What strategies to overcome adaptive defences do pathogen use to avoid recognition?

Answer 396

Antigenic variation - Variation of surface proteins to prevent recognition by memory lymphocytes and circumvent secondary immune responses

Question 397

c. Host tissue damage is the result of the activities of both the pathogen and the host’s defences. List three (3) ways in which the process of inflammation (a host innate defence) can cause tissue damage to the host.

Answer 397

Swelling→ tissue compression/abrasion
Extracellular release of digestive enzymes → damages surrounding tissues
Fibrosis → loss of tissue function

Question 398

Describe the pathogen activity during the incubation period

Answer 398

colonises body surface
infects host
begins multiplying
some evade host defences

Question 399

Describe the pathogen activity during the prodromal period

Answer 399

more evade host defences
multiplying
causing tissue damage

Question 400

Describe the pathogen activity during the disease period

Answer 400

multiplying (greatest numbers)
causing tissue damage (maximal damage)
many evade host defences

Question 401

Describe the host activity/experience during the prodromal period

Answer 401

non-specific symptoms, e.g. headaches, malaise
innate defences active, adaptive defences developing

Question 402

Describe the pathogen activity during the recovery period

Answer 402

overcome by host defences
numbers decreasing

Question 403

Describe the host activity/experience during the incubation period

Answer 403

no signs or symptoms
innate defences active, adaptive defences developing

Question 404

What is the host doing at the point marked “*” and why is this important?

Answer 404

Host defences are overcoming the pathogen thus pathogen numbers start to decrease.
If this does not occur the pathogen will continue to multiply, leading to severe tissue damage and potentially death.

Question 404

Describe the host activity/experience during the disease period

Answer 404

specific signs and symptoms, e.g. measles rash
innate and adaptive defences active

Question 404

Describe the host activity/experience during the recovery period

Answer 404

defences overcome pathogen
signs and symptoms subside
recovery

Question 405

What is the time frame of an acute infection?

Answer 405

Short term

Question 406

What is the time frame of an chronic infection?

Answer 406

Long term to lifelong

Question 407

Describe the disease characteristics in a acute infection

Answer 407

Acute, symptomatic followed by recovery

Question 407

What is the time frame of an latent infection?

Answer 407

Lifelong

Question 408

Describe the disease characteristics in a chronic infection

Answer 408

Acute, symptomatic followed by apparent recovery

Question 409

Describe the disease characteristics in a latent infection

Answer 409

Acute, symptomatic followed by apparent recovery, reactivation at later time(s)

Question 410

Describe what happens to the pathogen in an acute infection

Answer 410

Cleared

Question 411

Describe what happens to the pathogen in an chronic infection

Answer 411

Persists, multiplies slowly

Question 412

Describe what happens to the pathogen in an latent infection

Answer 412

Persists inside host cells, does not multiply between reactivations

Question 413

Describe the damage to the host in an acute infection

Answer 413

Only during acute infection

Question 414

Describe the damage to the host in an chronic infection

Answer 414

Continual

Question 415

Describe the damage to the host in an latent infection

Answer 415

Only during initial acute infection or when reactivation

Question 416

When can transmission occur in an acute infection?

Answer 416

During any stage, when pathogen is multiplying

Question 417

When can transmission occur in an chronic infection?

Answer 417

At any time (pathogen always multiplying, host is a carrier)

Question 418

When can transmission occur in an latent infection?

Answer 418

During initial acute infection and reactivation (when pathogen multiplying and host symptomatic)

Question 419

Provide an example of an acute infection

Answer 419

Influenza, rhinovirus

Question 420

Provide an example of an chronic infection

Answer 420

Hepatitis B or C, HIV

Question 421

Provide an example of an latent infection

Answer 421

Herpes virus, HIV

Question 422

Identify which type of infection is represented by this graph

Answer 422

Latent

Question 423

Identify which type of infection is represented by this graph

Answer 423

Chronic (persistent)

Question 424

Identify which type of infection is represented by this graph

Answer 424

Acute