Question 1

Which of the following best describes the role of Toll-like receptors (TLRs) in innate immunity?

Accepted Answer

TLRs attach to pathogen-associated molecular patterns (PAMPs) and induce cytokine release.

Question 2

A patient presents with a low white blood cell (WBC) count. Which of the following is LEAST likely to be a cause?

Accepted Answer

Bacterial infection

Question 3

Which physical barrier is most responsible for preventing microbial entry into the lower respiratory tract?

Accepted Answer

Ciliary escalator

Question 4

Which of the following chemical factors is correctly matched with its antimicrobial function?

Accepted Answer

Lysozyme: destroys bacterial cell walls

Question 5

A patient with a parasitic worm infection is likely to have an elevated count of which leukocyte?

Accepted Answer

Eosinophils

Question 6

Which of the following best explains why normal microbiota are important for innate immunity?

Accepted Answer

They compete with pathogens for space and nutrients, and may produce substances harmful to pathogens.

Question 7

Which of the following is NOT a function of the lymphatic system in immunity?

Accepted Answer

Producing erythrocytes for oxygen transport

Question 8

Which of the following best describes the difference between innate and adaptive immunity?

Accepted Answer

Innate immunity is present at birth and responds rapidly to any pathogen; adaptive immunity is slower and specific to particular pathogens.

Question 9

Which of the following scenarios best illustrates microbial antagonism?

Accepted Answer

Normal microbiota outcompete pathogenic bacteria for nutrients in the gut, preventing infection.

Question 10

Which of the following is a correct sequence of events in the activation of the adaptive immune response by the innate immune system?

Accepted Answer

TLRs bind PAMPs → cytokines released → activation of T and B cells

Question 11

A patient is prescribed a broad-spectrum antibiotic, which disrupts their normal microbiota. Which of the following is a possible consequence?

Accepted Answer

Overgrowth of opportunistic pathogens such as Clostridioides difficile

Question 12

Which of the following best describes the function of neutrophils in the immune response?

Accepted Answer

They are highly phagocytic and are most active in the early stages of infection.

Question 13

Which of the following is an example of a chemical barrier in innate immunity?

Accepted Answer

Low pH of gastric juice

Question 14

Which of the following best explains why intact, healthy skin is an effective barrier to microbial invasion?

Accepted Answer

It is composed of tightly packed epithelial cells with keratin, and is dry and sheds regularly.

Question 15

Which of the following best describes the function of dendritic cells in the immune system?

Accepted Answer

They initiate adaptive immune responses by presenting antigens.

Question 16

A patient with an autoimmune disease is found to have a high WBC count. Which of the following best explains this finding?

Accepted Answer

Autoimmune diseases can stimulate increased production of leukocytes.

Question 17

Which of the following best describes the role of probiotics in human health?

Accepted Answer

They are live microbial cultures administered to exert a beneficial effect.

Question 18

Which of the following is a correct statement about the formation of blood cells?

Accepted Answer

All blood cells are created in the red bone marrow from stem cells via hematopoiesis.

Question 19

Which of the following best describes the function of the ciliary escalator?

Accepted Answer

It transports microbes trapped in mucus away from the lungs.

Question 20

Which of the following best describes the relationship between commensal microbiota and the host?

Accepted Answer

The microbiota benefit while the host is unharmed.

Innate Immunity: Nonspecific Defenses of the Host

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