Question 1

Which of the following innate immunity mechanisms is mismatched with its associated structure or body fluid?

Accepted Answer

The mucociliary escalator is associated with the respiratory tract, not the intestines.

All other choices are correctly matched: 
A) Lysozyme is found in tears and saliva 
C) The stomach has a highly acidic pH 
D) The skin has acidic pH, sebum, and fatty acids 
E) The urogenital tract has a low pH.

Question 2

Which of the following organisms can cause Pseudomembranous enterocolitis?

Accepted Answer

Clostridium difficile is the organism responsible for Pseudomembranous enterocolitis. Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli, and Streptococcus pyogenes are all potential causes of other types of bacterial infections.

Question 3

Which of the following types of cells are antigen presenters in humans?

Accepted Answer

Macrophages and dendritic cells are both antigen presenting cells (APCs) in humans. They process and present antigens to T cells, triggering an immune response. B lymphocytes and T helper cells can also present antigens, but they are not considered the primary APCs in humans.

Question 4

The mucociliary escalator functions to:

Accepted Answer

The mucociliary escalator is a protective mechanism in the respiratory system that uses cilia and mucus to trap and sweep microbes from the bronchi back up to the throat to be swallowed, preventing them from entering the lungs.

Question 5

Which of the following is NOT an integral part of the inflammatory process?

Accepted Answer

Antibody synthesis is not an integral part of the inflammatory process. Antibodies are part of the adaptive immune response, which takes longer to activate compared to the immediate, non-specific response of inflammation. The other choices (A-D) are all important steps in the inflammatory process.

Question 6

The aerobe to anaerobe ratio showing the greatest difference in concentrations occurs in the:

Accepted Answer

The intestinal tract has a very high number of anaerobic bacteria compared to aerobic bacteria, while other areas such as the mouth, skin, respiratory tract, and genitourinary tract have a more balanced ratio of aerobic to anaerobic bacteria.

Question 7

Which of the following is NOT a lymphoid organ?

Accepted Answer

The stomach is not a lymphoid organ. It is a part of the digestive system that secretes acid and enzymes to break down food. The other options are all lymphoid organs: tonsils and adenoids, spleen, appendix, and bone marrow. These organs play important roles in the immune system, producing and storing immune cells and antibodies to protect the body from infections and diseases.

Question 8

Neisseria species:

Accepted Answer

Neisseria species are Gram-negative cocci that are found as normal microbial flora of humans. They are not obligate intracellular parasites, and they do not cause serious diarrhea. They are not used as probiotics.

Question 9

Which of the following are the major phagocytic cells in the body?

Accepted Answer

Neutrophils and macrophages are the major phagocytic cells in the body. T and B lymphocytes are involved in immune responses but not phagocytosis. Basophils and eosinophils are involved in allergic reactions and parasitic infections, respectively, but have limited phagocytic activity. Erythrocytes are red blood cells and do not have phagocytic activity. Epithelial cells with cilia are involved in moving mucus and other substances along respiratory and reproductive tracts but are not phagocytic cells.

Question 10

Which of the following is rarely normal flora of the urethra?

Accepted Answer

The answer of Which of the following is rarely normal...

Question 11

Microbial colonization of the eye is inhibited by the presence of antimicrobial factors, like:

Accepted Answer

The answer of Microbial colonization of the eye is inhibited...

Question 12

Which of the following is NOT found in the epidermis layer?

Accepted Answer

The answer of Which of the following is NOT found...

Question 13

An organism found on human skin that derives benefit from the host but does NOT harm it is described as a/an:

Accepted Answer

A commensal organism benefits from its host without causing harm or providing any significant benefit in return.

Question 14

All of the following statements are correct about microbial colonization of the human body EXCEPT:

Accepted Answer

Cardiovascular normal flora do not exist as there is no normal microbiota in the cardiovascular system.

Question 15

Which of the following is NOT a symptom of periodontal disease?

Accepted Answer

Swollen tongue is not a symptom of periodontal disease, but it can be a symptom of other health conditions such as allergies or infections. Red, swollen gums, bleeding gums, gum shrinkage, and teeth drifting apart are all common symptoms of periodontal disease.

Question 16

Which part of the genitourinary tract maintains a normal flora population?

Accepted Answer

The answer of Which part of the genitourinary tract maintains...

Question 17

Which of the following should be free from microbes in a healthy individual?

Accepted Answer

Cerebrospinal fluid should be free from microbes in a healthy individual as it is a sterile fluid that functions to protect the brain and spinal cord. The nose, mouth, skin, and genitourinary tract can all harbor various types of microbes even in a healthy individual.

Question 18

Which of the following organisms are commonly used as probiotics?

Accepted Answer

Bifidobacterium and Lactobacillus acidophilus are commonly used as probiotics. Streptococcus mutans is not typically used as a probiotic and is associated with causing dental caries. Bacteroides and Enterobacter species are not commonly used as probiotics. Diphtheroids and Fusobacterium species are not commonly used as probiotics.

Question 19

Which of the following is correct regarding inflammation?

Accepted Answer

Inflammation is a non-specific response that occurs in the same manner regardless of the type of pathogen or injury.

Question 20

Which of the following is a primary lymphoid organ?

Accepted Answer

The thymus is a primary lymphoid organ as it is the site where T cells mature and differentiate. The other choices are secondary lymphoid organs which play a role in the activation and proliferation of lymphocytes.

Quiz 23: Human Microbiota and Nonspecific Host Defenses