Question 1

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

Accepted Answer

Innate immunity is a generalized, immediate response that usually does not clear pathogens, while adaptive immunity is highly specific, takes time to develop, and confers immunological memory.

Question 2

A patient is exposed to a novel virus. Which immune response is responsible for the immediate, non-specific defense against this virus?

Accepted Answer

Release of interferons and activation of natural killer (NK) cells

Question 3

Which of the following is NOT considered a physical barrier in the innate immune system?

Accepted Answer

Interleukin-2 (IL-2)

Question 4

During an infection, which cell type is most likely to be the first to arrive at the site of bacterial invasion and perform phagocytosis?

Accepted Answer

Neutrophils

Question 5

Which cytokine is primarily responsible for signaling among leukocytes and other tissues?

Accepted Answer

Interleukins (ILs)

Question 6

A researcher is studying a protein that stimulates stem cells to divide. Which class of cytokine is she most likely investigating?

Accepted Answer

Growth factors

Question 7

Which of the following best explains why humans are generally resistant to most plant and animal pathogens?

Accepted Answer

Humans lack the correct chemical receptors and have physiological conditions incompatible with those pathogens.

Question 8

Which of the following is a function of dendritic cells in the immune response?

Accepted Answer

Transporting antigens to secondary lymphoid tissues and presenting them to T cells

Question 9

A patient with a parasitic worm infection is likely to have an increased number of which type of leukocyte?

Accepted Answer

Eosinophils

Question 10

Which of the following best describes the process of clonal selection in adaptive immunity?

Accepted Answer

Each lymphocyte bears a single type of receptor with unique specificity, and only those that recognize the antigen proliferate.

Question 11

Which of the following equations best represents the relationship between the number of mature lymphocyte clones ($$N$$), the number of unique antigen receptors ($$R$$), and the probability of antigen recognition ($$P$$), assuming each clone has a unique receptor and $$P = \frac{N}{R}$$?

Accepted Answer

$$P = \frac{N}{R}$$

Question 12

Which of the following is a key feature of adaptive immunity that is not present in innate immunity?

Accepted Answer

Highly specific recognition of antigens and immunological memory

Question 13

A patient is unable to produce interferons. Which of the following would be the most likely consequence?

Accepted Answer

Increased susceptibility to viral infections due to impaired inhibition of viral replication

Question 14

Which of the following best describes the role of major histocompatibility complex (MHC) proteins in adaptive immunity?

Accepted Answer

They present processed antigen peptides to T cells, enabling antigen recognition.

Question 15

Which of the following scenarios best illustrates the concept of immunological memory?

Accepted Answer

A person recovers more quickly from a second infection with the same virus due to rapid activation of memory B and T cells.

Question 16

Which of the following is the correct sequence of events in the adaptive immune response to a bacterial infection?

Accepted Answer

Antigen presentation by dendritic cells → Activation of T cells → Activation of B cells → Antibody production

Question 17

Which of the following best explains why NK cells are important in the innate immune response to viral infections?

Accepted Answer

They kill virus-infected cells before the adaptive immune response is activated.

Question 18

A mutation prevents a patient’s macrophages from producing tumor necrosis factor (TNF). Which of the following is a likely consequence?

Accepted Answer

Impaired ability to kill tumor cells and regulate inflammation

Question 19

Which of the following best describes the role of chemokines in the immune response?

Accepted Answer

They act as chemotactic signals to direct leukocyte movement.

Question 20

Which of the following is a correct statement about antigen recognition by B cell receptors (BCR) and T cell receptors (TCR)?

Accepted Answer

BCRs recognize whole antigens (proteins, carbohydrates, lipids, nucleic acids), while TCRs recognize processed peptides presented by MHC proteins.

Organization of the Immune System: Overview and Cellular Components

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