Chapter 15 review questions

Which of the following would be a sign of an infection?

A. muscle aches

B. headache

C. fever

D. nausea

C. fever

Which of the following is an example of a noncommunicable infectious disease?

A. infection with a respiratory virus

B. food poisoning due to a preformed bacterial toxin in food

C. skin infection acquired from a dog bite

D. infection acquired from the stick of a contaminated needle

B. food poisoning due to a preformed bacterial toxin in food

During an oral surgery, the surgeon nicked the patient's gum with a sharp instrument. This allowed Streptococcus, a bacterium normally present in the mouth, to gain access to the blood. As a result, the patient developed bacterial endocarditis (an infection of the heart). Which type of disease is this?

A. iatrogenic

B. nosocomial

C. vectors

D. zoonotic

A. iatrogenic

Which period is the stage of disease during which the patient begins to present general signs and symptoms?

A. convalescence

B. incubation

C. illness

D. prodromal

D. prodromal

A communicable disease that can be easily transmitted from person to person is which type of disease?

A. contagious

B. iatrogenic

C. acute

D. nosocomial

A. contagious

Which of the following is a pathogen that could not be identified by the original Koch's postulates?

A. Staphylococcus aureus

B. Pseudomonas aeruginosa

C. Human immunodeficiency virus

D. Salmonella enterica serovar Typhimurium

C. Human immunodeficiency virus

Pathogen A has an ID50 of 50 particles, pathogen B has an ID50 of 1,000 particles, and pathogen C has an ID50 of 1 × 106 particles. Which pathogen is most virulent?

A. pathogen A

B. pathogen B

C. pathogen C

A. pathogen A

Which of the following choices lists the steps of pathogenesis in the correct order?

A. invasion, infection, adhesion, exposure

B. adhesion, exposure, infection, invasion

C. exposure, adhesion, invasion, infection

D. disease, infection, exposure, invasion

C. exposure, adhesion, invasion, infection

Which of the following would be a virulence factor of a pathogen?

A. a surface protein allowing the pathogen to bind to host cells

B. a secondary host the pathogen can infect

C. a surface protein the host immune system recognizes

D. the ability to form a provirus

A. a surface protein allowing the pathogen to bind to host cells

You have recently identified a new toxin. It is produced by a gram-negative bacterium. It is composed mostly of protein, has high toxicity, and is not heat stable. You also discover that it targets liver cells. Based on these characteristics, how would you classify this toxin?

A. superantigen

B. endotoxin

C. exotoxin

D. leukocidin

A. superantigen

Which of the following applies to hyaluronidase?

A. It acts as a spreading factor.

B. It promotes blood clotting.

C. It is an example of an adhesin.

D. It is produced by immune cells to target pathogens.

A. It acts as a spreading factor.

Phospholipases are enzymes that do which of the following?

A. degrade antibodies

B. promote pathogen spread through connective tissue.

C. degrade nucleic acid to promote spread of pathogen

D. degrade cell membranes to allow pathogens to escape phagosomes

D. degrade cell membranes to allow pathogens to escape phagosomes

Which of the following is a major virulence factor for the fungal pathogen Cryptococcus?

A. hemolysin

B. capsule

C. collagenase

D. fimbriae

B. capsule

Which of the following pathogens undergoes antigenic variation to avoid immune defenses?

A. Candida

B. Cryptococcus

C. Plasmodium

D. Giardia

C. Plasmodium

A difference between an acute disease and chronic disease is that chronic diseases have an extended period of __________.

illness

A person steps on a rusty nail and develops tetanus. In this case, the person has acquired a(n) __________ disease.

noncommunicable

A(n) __________ pathogen causes disease only when conditions are favorable for the microorganism because of transfer to an inappropriate body site or weakened immunity in an individual.

opportunistic

The concentration of pathogen needed to kill 50% of an infected group of test animals is the __________.

LD50

A(n) __________ infection is a small region of infection from which a pathogen may move to another part of the body to establish a second infection.

focal

Cilia, fimbriae, and pili are all examples of structures used by microbes for __________

adhesion

The glycoprotein adhesion gp120 on HIV must interact with __________ on some immune cells as the first step in the process of infecting the cell.

CD4

Adhesins are usually located on __________ of the pathogen and are composed mainly of __________ and __________.

surface; proteins; sugars

The Shiga and diphtheria toxins target __________ in host cells.

protein synthesis

Antigenic __________ is the result of reassortment of genes responsible for the production of influenza virus spike proteins between different virus particles while in the same host, whereas antigenic __________ is the result of point mutations in the spike proteins.

shift; drift

Candida can invade tissue by producing the exoenzymes __________ and __________.

protease and phospholipase

The larval form of Schistosoma mansoni uses a __________ to help it gain entry through intact skin.

protease

Brian goes to the hospital after not feeling well for a week. He has a fever of 38 °C (100.4 °F) and complains of nausea and a constant migraine. Distinguish between the signs and symptoms of disease in Brian’s case.

Brian’s sign is his fever, and his symptoms are nausea and migraine

Describe the virulence factors associated with the fungal pathogen Aspergillus.

• Thermotolerance – Grows at body temperature.

• Small conidia – Easily inhaled into lungs.

• Melanin – Protects from immune attack.

• Gliotoxin – Suppresses immune cells.

• Enzymes – Break down host tissues.

• Biofilms – Help resist drugs and immunity.

Explain how helminths evade the immune system.

• Molecular mimicry – They produce molecules similar to host proteins to avoid detection.

• Immune suppression – Release compounds that suppress or divert immune responses.

• Thick outer coverings – Tough outer layers (like cuticles or teguments) protect them from immune attack.

• Migration – Move through tissues to avoid immune cells.

• Antigen variation – Change surface proteins to escape recognition.