Which of the following outcomes would be expected if somatic hypermutation did not occur?
a. The diversity of pattern-recognition receptors would be significantly lowered.
b. B and T lymphocytes would not be able to produce receptors that recognize antigens.
c. The adaptive immune response would not be activated by pathogens.
d. The secondary immune response to a repeat infection would produce the same antibodies as those made in the primary immune response.

Why is clonal selection necessary for the adaptive immune response but not the innate immune response? Select True or False for each statement.

T/F The adaptive immune response uses receptors to recognize pathogens, and the innate immune response does not.

T/F There is more receptor diversity in the adaptive immune response than in the innate immune response.

T/F Cells in the innate immune response do not require activation, and those in the adaptive immune response do.

T/F Clonal selection is used for targeting pathogens, and the innate immune response is used only to stop blood flow from the wound.

What would a vaccine have to contain to protect a patient from chicken pox? Explain why we don't have vaccines for HIV.

In the condition myasthenia gravis, antibodies bind to and block certain receptors on muscle cells, preventing muscle contraction. This condition is best classified as an

a. Immunodeficiency disorder.

b. Exaggerated immune reaction.

c. Allergic reaction.

d. Autoimmune disorder.

Which of the following statements is not true?

a. An antibody has more than one antigen-binding site.

b. An antigen can have different epitopes.

c. A lymphocyte has receptors for multiple and different antigens.

d. A bacterium has more than one antigen.

Propose a hypothesis to explain how self-reactive B cells are identified and eliminated during maturation.

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In developed countries, an enormous change has occurred within the human body over the past century—the loss of parasitic worms. Due to improvements in sanitation, roundworms that have inhabited human intestines (such as the hookworm above) and challenged our immune system for millions of years are no longer a threat. Does the end of this long-term relationship come at a cost?

What is the hygiene hypothesis? What correlation does it attempt to explain?