What is the key difference between a primary and a secondary immune response to the same antigen?

Correct answer: The secondary response is faster and more efficient due to the presence of a larger population of pre-existing memory cells.

Explanation

Immunological memory is the hallmark of the adaptive immune system. The first encounter with an antigen elicits a primary response and generates a large pool of long-lived memory lymphocytes. A subsequent encounter with the same antigen triggers a secondary response, which is much faster, stronger, and more effective because this expanded population of memory cells is readily activated.

Other questions

Question 1

Which statement accurately distinguishes between the innate and adaptive immune systems?

Question 2

What is the general term for the microbe-associated molecules that are recognized by the innate immune system's receptor proteins?

Question 3

According to the text, approximately how many different Toll-like receptors (TLRs) does a human make?

Question 4

Which Toll-like receptor (TLR) is responsible for recognizing lipopolysaccharide (LPS) on the outer membrane of Gram-negative bacteria?

Question 5

What is described as the pivotal complement component that is cleaved and activated by all three pathways of complement activation?

Question 6

How do Natural Killer (NK) cells primarily distinguish virus-infected cells from healthy cells?

Question 7

Which cell type is described as the crucial link between the innate and adaptive immune systems because it ingests pathogens and presents their antigens to T cells?

Question 8

What is the approximate number of lymphocytes in the human body, making the immune system comparable in cell mass to the liver or brain?

Question 9

Where do T cells and B cells primarily develop, respectively, in adult mammals?

Question 11

Which of the following is NOT listed as a mechanism for establishing immunological self-tolerance?

Question 12

Which class of immunoglobulin is the first to be made by a developing B cell and is also the major class secreted in the early stages of a primary antibody response?

Question 13

How many antigen-binding sites does a secreted IgM molecule have, due to its pentameric structure?

Question 14

Which immunoglobulin class is secreted in the largest quantities during a secondary immune response and is capable of crossing the placenta from mother to fetus?

Question 15

Which immunoglobulin class is primarily responsible for allergic reactions like hay fever and asthma by binding to Fc receptors on mast cells?

Question 16

What is the primary function of the activation-induced deaminase (AID) enzyme in activated B cells?

Question 17

What is a key structural difference between T cell receptors (TCRs) and B cell receptors (BCRs)?

Question 18

To which cells do class I and class II MHC proteins primarily present foreign peptides, respectively?

Question 19

What is the typical length of the peptides displayed in the peptide-binding groove of Class I MHC proteins?

Question 20

From where do the peptides presented by class II MHC proteins on antigen-presenting cells (APCs) mainly originate?