Which statement best describes the difference between responses of effector B cells (plasma cells) and those of cytotoxic T cells? a. B cells confer active immunity; cytotoxic T cells confer passive immunity. b. B cells respond the first time a pathogen is present; cytotoxic T cells respond subsequent times. c. B cells secrete antibodies against a pathogen; cytotoxic T cells kill pathogen-infected host cells. d. B cells carry out the cell-mediated response; cytotoxic T cells carry out the humoral response.
Ch. 43 - The Immune System
Chapter 43, Problem 5
Which of the following should be the same in identical twins? a. the set of antibodies produced b. the set of MHC molecules produced c. the set of T cell antigen receptors produced d. the set of immune cells eliminated as self-reactive
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Step 1: Understand the question. The question is asking which of the given options should be the same in identical twins. Identical twins are genetically identical, meaning they have the same DNA sequence.
Step 2: Analyze each option. Option a, the set of antibodies produced, is not the same in identical twins. Antibodies are produced in response to specific antigens, which can vary based on individual experiences with pathogens.
Step 3: Option b, the set of MHC molecules produced, should be the same in identical twins. MHC molecules are genetically determined, and since identical twins have the same DNA, they should produce the same set of MHC molecules.
Step 4: Option c, the set of T cell antigen receptors produced, is not the same in identical twins. T cell receptors are generated through a random process of gene rearrangement, which is not genetically determined.
Step 5: Option d, the set of immune cells eliminated as self-reactive, is not the same in identical twins. This process is influenced by individual experiences with pathogens and is not genetically determined. Therefore, the correct answer is option b, the set of MHC molecules produced.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Identical Twins and Genetics
Identical twins originate from a single fertilized egg that splits into two embryos, resulting in genetically identical individuals. This genetic similarity means that they share the same DNA, which influences various biological traits, including immune system components. However, environmental factors can still lead to differences in immune responses.
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Genetic Code
MHC Molecules
Major Histocompatibility Complex (MHC) molecules are proteins found on cell surfaces that play a crucial role in the immune system by presenting antigens to T cells. In identical twins, the MHC molecules are genetically identical, which means they will have the same set of MHC molecules, influencing their immune responses and compatibility.
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Which Molecules Freely Cross Membranes?
T Cell Antigen Receptors
T cell antigen receptors (TCRs) are unique proteins on the surface of T cells that recognize specific antigens. While identical twins share the same genetic makeup, the TCRs are generated through a random recombination process during T cell development, leading to variability. Therefore, the set of T cell antigen receptors is not necessarily the same in identical twins.
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Related Practice
Textbook Question
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Textbook Question
Which of the following statements is true? (A) An antibody has one antigen-binding site. (B) A lymphocyte has receptors for a single antigen. (C) Every antigen has a single epitope. (D) A liver or muscle cell makes two classes of MHC molecule
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Textbook Question
Which of the following statements is true?
a. An antibody has one antigen-binding site.
b. A lymphocyte has receptors for a single antigen.
c. Every antigen has a single epitope.
d. A liver or muscle cell makes two classes of MHC molecule.
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