Q: Which equation best represents the probability of matching MHC molecules for organ transplantation, given that there are 3 loci for MHC-I and 3 loci for MHC-II, each with over 100 alleles?

$$100 \times 100 \times 100 \times 100 \times 100 \times 100$$

Question 1

Which of the following best describes the function of complement proteins in the innate immune system?

Accepted Answer

They attach to microbes, activate inflammation, and lyse invading cells.

Question 2

A burn victim is at increased risk for infection primarily because:

Accepted Answer

Their skin barrier is compromised, allowing pathogens to enter.

Question 3

Which equation best represents the possible combinations of antibody diversity in humans, given that there are approximately 144,000 possible heavy chain combinations and 144,000 possible light chain combinations?

Accepted Answer

$$144,000 	imes 144,000$$

Question 4

Which cell type is responsible for releasing histamine during the inflammatory response and is also involved in allergic reactions?

Accepted Answer

Mast cells

Question 5

During phagocytosis, which step occurs immediately after a microbe is engulfed by a macrophage?

Accepted Answer

A vacuole containing the microbe forms inside the cell.

Question 6

Which of the following is NOT a function of the normal flora (microbiome) in human nonspecific defenses?

Accepted Answer

Directly attacking virus-infected cells.

Question 7

Which of the following best explains why organ transplants are often rejected by the recipient's immune system?

Accepted Answer

The donor's MHC molecules act as antigens and trigger a cellular immune response.

Question 8

Which of the following statements about the humoral immune response is correct?

Accepted Answer

It involves antibodies binding to free-floating or surface-bound antigens.

Question 9

A person exposed to a pathogen for the first time develops memory cells. Upon a second exposure, the immune response is faster due to:

Accepted Answer

Immunological memory

Question 10

Which of the following is a major difference between antibodies and T cell receptors?

Accepted Answer

Antibodies bind free-floating antigens, while T cell receptors bind antigens presented with MHC proteins.

Question 11

Which of the following best describes the role of helper T cells (TH cells) in the immune system?

Accepted Answer

They assist both the cellular and humoral immune systems by stimulating B and TC cells to divide.

Question 12

Which of the following is a real-world example of passive immunity?

Accepted Answer

Antibodies transferred from mother to child via breast milk

Question 13

Which equation best represents the probability of matching MHC molecules for organ transplantation, given that there are 3 loci for MHC-I and 3 loci for MHC-II, each with over 100 alleles?

Accepted Answer

$$100 	imes 100 	imes 100 	imes 100 	imes 100 	imes 100$$

Question 14

Which of the following is a primary emergency treatment for anaphylactic shock?

Accepted Answer

Administration of epinephrine

Question 15

Which of the following is a plausible reason why vaccines for rapidly mutating viruses (like influenza or COVID) may require frequent updates?

Accepted Answer

The viruses evolve new surface antigens, reducing vaccine effectiveness.

Question 16

Which of the following is a function of the inflammatory response?

Accepted Answer

Limits spread of pathogens to neighboring tissues and attracts phagocytes.

Question 17

Which of the following best describes the genetic basis of antibody diversity?

Accepted Answer

Antibody genes are reshuffled by recombination during B cell development.

Question 18

Which of the following is a characteristic of the immune system that allows it to respond to millions of different antigens?

Accepted Answer

Diversity

Question 19

Which of the following is a real-world example of the immune system distinguishing 'self' from 'non-self'?

Accepted Answer

MHC proteins on cell surfaces act as molecular fingerprints.

Question 20

Which of the following is a plausible explanation for the development of autoimmune diseases?

Accepted Answer

Failure to tolerate self molecules during B and T cell development.

Defenses Against Disease: The Immune System

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