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1.1 The study of life Read Online
Viewed from space, Earth offers no clues about the diversity of life forms that reside there. The first forms of life on Earth are thought to have been microorganisms that existed for billions of years in the ocean before plants and animals appeared. The mammals, birds, and flowers so familiar to us are all relatively recent, originating 130 to 200 million years ago. Humans have inhabited this planet for only the last 2.5 million years, and only in the last 200,000 years have humans started looking like we do today.
Question: Which of the following do not induce a strong immune response?
Choices:
lipids
proteins
polysaccharides
nucleic acids
lipids AND nucleic acids
Question: There are ______ classes of antibody.
Choices:
1
3
5
7
Question: A terrorist mad scientist develops a new blood-borne virus that will completely shut down presentation of viral epitopes on MHC molecules in the cells it infects. He produces an internet video describing it and how it will be indestructible by CD8+ cytotoxic T-cells and will kill millions (if not billions) of people. The medical community quickly denounces and discredits his plan as impossible, and the whole thing is quickly forgotten-why?
Choices:
CD8+ T-cells are not the cells that are responsible for killing virally-infected cells. The terrorist mad scientist is a misinformed idiot.
While CD8+ T-cells ARE important for eliminating a viral infection, they are not the ONLY things that are capable of doing so. Natural Killer cells can kill virally-infected cells that have shut down MHC antigen presentation, and interferons can assist in clearing virally-infected cells.
A blood-borne virus would not be capable of rapidly infecting millions of people, due to its difficult mode of transmission.
B-cells would be primed right away to produce complement proteins to destroy the virus. This would prevent cells from being infected with it in the first place. His plot would be foiled.
While CD8+ T-cells ARE important for eliminating a viral infection, they are not the ONLY things that are capable of doing so. Natural Killer cells can kill virally-infected cells that have shut down MHC antigen presentation, and interferons can assist in clearing virally-infected cells AND a blood-borne virus would not be capable of rapidly infecting millions of people, due to its difficult mode of transmission.
Question: The stimulation of B cells to divide and mature is provided by
Choices:
T helper cells.
macrophages.
T cytotoxic cells.
plasma cells.
Question: How long after initiation of a primary response do significant amounts of antibody appear in the blood?
Choices:
one day
10-14 days
4 weeks
6 months
Question: Antigens may be processed for presentation by
Choices:
macrophages.
dendritic cells.
erythrocytes.
T cytotoxic cells.
macrophages AND dendritic cells.
Question: The function of the secretory component of the IgA molecule is
Choices:
to protect IgA from being destroyed by proteolytic enzymes.
to coat the antigen.
opsonization.
to fix IgA to the antigen.
Question: CD4 cells are often
Choices:
T helper cells.
T suppresser cells.
T cytotoxic cells.
T hypersensitivity cells.
Question: Memory cells may take the form of
Choices:
B cells.
T cytotoxic cells.
T helper cells.
All of the choices are correct.
Question: "Clonal selection" and "clonal expansion"
Choices:
implies that each individual lymphocyte produces a single antibody.
describes how the adaptive immune system can produce millions of different antibodies.
depends on an antibody recognizing a specific epitope.
are based on random processes.
All of the above
Question: According to the clonal selection theory
Choices:
antibodies are modified, at the time of antigen exposure, to specifically react with the antigen.
self-reactive T cells are killed in the thymus.
B cells producing autoantibodies are eliminated in the thymus.
each B cell is already programmed to produce a specific antibody.
self-reactive T cells are killed in the thymus AND B cells producing autoantibodies are eliminated in the thymus.
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