Microbiology Chapter 15 Exam Questions with 100% Correct Answers | Verified | Updated

Microbiology Chapter 15 Exam Questions with 100% Correct Answers | Verified | Updated 1) The most frequently used portal of entry for pathogens is the A) mucous membranes of the respiratory tract. B) mucous membranes of the gastrointestinal tract. C) skin. D) parenteral route. E) All of these portals are used equally. - answerA) mucous membranes of the respiratory tract. 2) The ability of some microbes, such as Trypanosoma or Giardia to alter their surface molecules and evade destruction by the host's antibodies is called A) antigenic variation. B) lysogenic conversion. C) virulence. D) cytopathic effect. E) cytocidal effect. - answerA) antigenic variation. 3) Most pathogens that gain access through the skin A) can penetrate intact skin. B) just infect the skin itself. C) enter through hair follicles and sweat ducts. D) must adhere first while their invasive factors allow them to penetrate. E) must be injected. - answerC) enter through hair follicles and sweat ducts. 4) The ID50 is A) a measure of pathogenicity. B) the dose that will cause an infection in 50 percent of the test population. C) the dose that will kill some of the test population. D) the dose that will cause an infection in some of the test population. E) the dose that will kill 50 percent of the test population. - answerB) the dose that will cause an infection in 50 percent of the test population. 5) All of the following contribute to a pathogen's invasiveness EXCEPT A) toxins. B) capsules. C) cell wall components. D) hyaluronidase. E) coagulases. - answerA) toxins 6) Which of the following statements is FALSE? A) Leukocidins destroy neutrophils. B) Hemolysins lyse red blood cells. C) Hyaluronidase breaks down substances between cells. D) Kinase destroys fibrin clots. E) Coagulase destroys blood clots. - answerE) Coagulase destroys blood clots. 7) Which of the following statements about exotoxins is generally FALSE? A) They are more potent than endotoxins. B) They are composed of proteins. C) They are resistant to heat. D) They have specific methods of action. E) They are produced by gram-positive bacteria. - answerC) They are resistant to heat. 8) Endotoxins are A) associated with gram-positive bacteria. B) molecules that bind nerve cells. C) part of the gram-negative cell wall. D) excreted from the cell. E) A-B toxins. - answerC) part of the gra