Question 1

Which of the following best describes the role of keratin in the epidermis as shown in the first image?

Accepted Answer

Keratin provides a physical barrier that prevents microbial entry and is frequently shed, removing attached microbes.

Question 2

A patient presents with a fever of 39°C after a bacterial infection. Which of the following statements best explains the physiological benefit of this fever?

Accepted Answer

Fever slows the growth of heat-limited microbes and increases the rate of phagocytosis.

Question 3

Which phase of phagocytosis is depicted when a phagocyte extends pseudopods to engulf a bacterium, as shown in the fifth image?

Accepted Answer

Ingestion

Question 4

Which of the following is NOT a function of inflammation as illustrated in the sixth image?

Accepted Answer

Decreasing blood flow to the affected area

Question 5

A patient with a genetic deficiency in lysozyme production would be most susceptible to which of the following?

Accepted Answer

Increased bacterial infections due to impaired degradation of peptidoglycan in bacterial cell walls

Question 6

Which leukocyte is primarily responsible for releasing histamine and causing inflammation, as shown in the fourth image?

Accepted Answer

Basophil

Question 7

Which of the following best describes the process of opsonization in the complement system, as shown in the ninth image?

Accepted Answer

Complement proteins coat microbes, enhancing their recognition and ingestion by phagocytes.

Question 8

A patient is infected with a parasitic worm. Which leukocyte is most likely to increase in number to combat this infection?

Accepted Answer

Eosinophil

Question 9

Which of the following is a direct effect of interferon (IFN) release by virus-infected cells, as shown in the eleventh image?

Accepted Answer

Stimulation of neighboring cells to produce antiviral proteins

Question 10

Which of the following best explains why normal microflora are considered a chemical barrier to infection?

Accepted Answer

They compete with pathogens for nutrients and space, preventing pathogen colonization.

Question 11

A patient with a wound infection develops swelling, redness, heat, and pain at the site. Which stage of inflammation is responsible for these symptoms?

Accepted Answer

Vasodilation

Question 12

Which of the following best describes the function of transferrins in innate immunity?

Accepted Answer

They bind and sequester iron, limiting bacterial growth.

Question 13

Which of the following is a characteristic of the innate immune system but NOT the adaptive immune system?

Accepted Answer

It responds rapidly and is always present.

Question 14

Which of the following best explains why fever above 43°C can be life-threatening?

Accepted Answer

It can denature essential proteins and enzymes in the human body.

Question 15

Which of the following is the correct sequence of events in phagocytosis?

Accepted Answer

Chemotaxis → Adherence → Ingestion → Digestion

Question 16

Which of the following is a function of natural killer (NK) cells in innate immunity?

Accepted Answer

They kill infected body cells and tumor cells by recognizing abnormal proteins on their surface.

Question 17

Which of the following best describes the role of the membrane attack complex (MAC) in the complement system?

Accepted Answer

It forms pores in the microbial membrane, leading to cell lysis.

Question 18

A patient with a burn injury loses the outer layer of skin. Which aspect of innate immunity is most compromised?

Accepted Answer

Physical barrier

Question 19

Which of the following is a plausible consequence of impaired ciliary function in the respiratory tract?

Accepted Answer

Decreased removal of microbes trapped in mucus, leading to increased respiratory infections

Question 20

Which of the following best explains why the normal microflora is considered part of the innate immune system?

Accepted Answer

It prevents the growth of pathogens through competitive exclusion and microbial antagonism.

Innate Immunity: The First Line of Defense in the Human Body

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