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Biology for AP® Courses

Test Prep for AP® Courses

Biology for AP® CoursesTest Prep for AP® Courses
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  1. Preface
  2. Unit 1
    1. 1 The Study of Life
      1. Introduction
      2. 1.1 The Science of Biology
      3. 1.2 Themes and Concepts of Biology
      4. Key Terms
      5. Chapter Summary
      6. Review Questions
      7. Critical Thinking Questions
      8. Test Prep for AP® Courses
    2. 2 The Chemical Foundation of Life
      1. Introduction
      2. 2.1 Atoms, Isotopes, Ions, and Molecules: The Building Blocks
      3. 2.2 Water
      4. 2.3 Carbon
      5. Key Terms
      6. Chapter Summary
      7. Review Questions
      8. Critical Thinking Questions
      9. Test Prep for AP® Courses
      10. Science Practice Challenge Questions
    3. 3 Biological Macromolecules
      1. Introduction
      2. 3.1 Synthesis of Biological Macromolecules
      3. 3.2 Carbohydrates
      4. 3.3 Lipids
      5. 3.4 Proteins
      6. 3.5 Nucleic Acids
      7. Key Terms
      8. Chapter Summary
      9. Review Questions
      10. Critical Thinking Questions
      11. Test Prep for AP® Courses
      12. Science Practice Challenge Questions
  3. Unit 2
    1. 4 Cell Structure
      1. Introduction
      2. 4.1 Studying Cells
      3. 4.2 Prokaryotic Cells
      4. 4.3 Eukaryotic Cells
      5. 4.4 The Endomembrane System and Proteins
      6. 4.5 Cytoskeleton
      7. 4.6 Connections between Cells and Cellular Activities
      8. Key Terms
      9. Chapter Summary
      10. Review Questions
      11. Critical Thinking Questions
      12. Test Prep for AP® Courses
      13. Science Practice Challenge Questions
    2. 5 Structure and Function of Plasma Membranes
      1. Introduction
      2. 5.1 Components and Structure
      3. 5.2 Passive Transport
      4. 5.3 Active Transport
      5. 5.4 Bulk Transport
      6. Key Terms
      7. Chapter Summary
      8. Review Questions
      9. Critical Thinking Questions
      10. Test Prep for AP® Courses
      11. Science Practice Challenge Questions
    3. 6 Metabolism
      1. Introduction
      2. 6.1 Energy and Metabolism
      3. 6.2 Potential, Kinetic, Free, and Activation Energy
      4. 6.3 The Laws of Thermodynamics
      5. 6.4 ATP: Adenosine Triphosphate
      6. 6.5 Enzymes
      7. Key Terms
      8. Chapter Summary
      9. Review Questions
      10. Critical Thinking Questions
      11. Test Prep for AP® Courses
      12. Science Practice Challenge Questions
    4. 7 Cellular Respiration
      1. Introduction
      2. 7.1 Energy in Living Systems
      3. 7.2 Glycolysis
      4. 7.3 Oxidation of Pyruvate and the Citric Acid Cycle
      5. 7.4 Oxidative Phosphorylation
      6. 7.5 Metabolism without Oxygen
      7. 7.6 Connections of Carbohydrate, Protein, and Lipid Metabolic Pathways
      8. 7.7 Regulation of Cellular Respiration
      9. Key Terms
      10. Chapter Summary
      11. Review Questions
      12. Critical Thinking Questions
      13. Test Prep for AP® Courses
      14. Science Practice Challenge Questions
    5. 8 Photosynthesis
      1. Introduction
      2. 8.1 Overview of Photosynthesis
      3. 8.2 The Light-Dependent Reaction of Photosynthesis
      4. 8.3 Using Light to Make Organic Molecules
      5. Key Terms
      6. Chapter Summary
      7. Review Questions
      8. Critical Thinking Questions
      9. Test Prep for AP® Courses
      10. Science Practice Challenge Questions
    6. 9 Cell Communication
      1. Introduction
      2. 9.1 Signaling Molecules and Cellular Receptors
      3. 9.2 Propagation of the Signal
      4. 9.3 Response to the Signal
      5. 9.4 Signaling in Single-Celled Organisms
      6. Key Terms
      7. Chapter Summary
      8. Review Questions
      9. Critical Thinking Questions
      10. Test Prep for AP® Courses
      11. Science Practice Challenge Questions
    7. 10 Cell Reproduction
      1. Introduction
      2. 10.1 Cell Division
      3. 10.2 The Cell Cycle
      4. 10.3 Control of the Cell Cycle
      5. 10.4 Cancer and the Cell Cycle
      6. 10.5 Prokaryotic Cell Division
      7. Key Terms
      8. Chapter Summary
      9. Review Questions
      10. Critical Thinking Questions
      11. Test Prep for AP® Courses
      12. Science Practice Challenge Questions
  4. Unit 3
    1. 11 Meiosis and Sexual Reproduction
      1. Introduction
      2. 11.1 The Process of Meiosis
      3. 11.2 Sexual Reproduction
      4. Key Terms
      5. Chapter Summary
      6. Review Questions
      7. Critical Thinking Questions
      8. Test Prep for AP® Courses
      9. Science Practice Challenge Questions
    2. 12 Mendel's Experiments and Heredity
      1. Introduction
      2. 12.1 Mendel’s Experiments and the Laws of Probability
      3. 12.2 Characteristics and Traits
      4. 12.3 Laws of Inheritance
      5. Key Terms
      6. Chapter Summary
      7. Review Questions
      8. Critical Thinking Questions
      9. Test Prep for AP® Courses
      10. Science Practice Challenge Questions
    3. 13 Modern Understandings of Inheritance
      1. Introduction
      2. 13.1 Chromosomal Theory and Genetic Linkages
      3. 13.2 Chromosomal Basis of Inherited Disorders
      4. Key Terms
      5. Chapter Summary
      6. Review Questions
      7. Critical Thinking Questions
      8. Test Prep for AP® Courses
      9. Science Practice Challenge Questions
    4. 14 DNA Structure and Function
      1. Introduction
      2. 14.1 Historical Basis of Modern Understanding
      3. 14.2 DNA Structure and Sequencing
      4. 14.3 Basics of DNA Replication
      5. 14.4 DNA Replication in Prokaryotes
      6. 14.5 DNA Replication in Eukaryotes
      7. 14.6 DNA Repair
      8. Key Terms
      9. Chapter Summary
      10. Review Questions
      11. Critical Thinking Questions
      12. Test Prep for AP® Courses
      13. Science Practice Challenge Questions
    5. 15 Genes and Proteins
      1. Introduction
      2. 15.1 The Genetic Code
      3. 15.2 Prokaryotic Transcription
      4. 15.3 Eukaryotic Transcription
      5. 15.4 RNA Processing in Eukaryotes
      6. 15.5 Ribosomes and Protein Synthesis
      7. Key Terms
      8. Chapter Summary
      9. Review Questions
      10. Critical Thinking Questions
      11. Test Prep for AP® Courses
      12. Science Practice Challenge Questions
    6. 16 Gene Regulation
      1. Introduction
      2. 16.1 Regulation of Gene Expression
      3. 16.2 Prokaryotic Gene Regulation
      4. 16.3 Eukaryotic Epigenetic Gene Regulation
      5. 16.4 Eukaryotic Transcriptional Gene Regulation
      6. 16.5 Eukaryotic Post-transcriptional Gene Regulation
      7. 16.6 Eukaryotic Translational and Post-translational Gene Regulation
      8. 16.7 Cancer and Gene Regulation
      9. Key Terms
      10. Chapter Summary
      11. Review Questions
      12. Critical Thinking Questions
      13. Test Prep for AP® Courses
      14. Science Practice Challenge Questions
    7. 17 Biotechnology and Genomics
      1. Introduction
      2. 17.1 Biotechnology
      3. 17.2 Mapping Genomes
      4. 17.3 Whole-Genome Sequencing
      5. 17.4 Applying Genomics
      6. 17.5 Genomics and Proteomics
      7. Key Terms
      8. Chapter Summary
      9. Review Questions
      10. Critical Thinking Questions
      11. Test Prep for AP® Courses
      12. Science Practice Challenge Questions
  5. Unit 4
    1. 18 Evolution and Origin of Species
      1. Introduction
      2. 18.1 Understanding Evolution
      3. 18.2 Formation of New Species
      4. 18.3 Reconnection and Rates of Speciation
      5. Key Terms
      6. Chapter Summary
      7. Review Questions
      8. Critical Thinking Questions
      9. Test Prep for AP® Courses
      10. Science Practice Challenge Questions
    2. 19 The Evolution of Populations
      1. Introduction
      2. 19.1 Population Evolution
      3. 19.2 Population Genetics
      4. 19.3 Adaptive Evolution
      5. Key Terms
      6. Chapter Summary
      7. Review Questions
      8. Critical Thinking Questions
      9. Test Prep for AP® Courses
      10. Science Practice Challenge Questions
    3. 20 Phylogenies and the History of Life
      1. Introduction
      2. 20.1 Organizing Life on Earth
      3. 20.2 Determining Evolutionary Relationships
      4. 20.3 Perspectives on the Phylogenetic Tree
      5. Key Terms
      6. Chapter Summary
      7. Review Questions
      8. Critical Thinking Questions
      9. Test Prep for AP® Courses
      10. Science Practice Challenge Questions
  6. Unit 5
    1. 21 Viruses
      1. Introduction
      2. 21.1 Viral Evolution, Morphology, and Classification
      3. 21.2 Virus Infection and Hosts
      4. 21.3 Prevention and Treatment of Viral Infections
      5. 21.4 Other Acellular Entities: Prions and Viroids
      6. Key Terms
      7. Chapter Summary
      8. Review Questions
      9. Critical Thinking Questions
      10. Test Prep for AP® Courses
      11. Science Practice Challenge Questions
    2. 22 Prokaryotes: Bacteria and Archaea
      1. Introduction
      2. 22.1 Prokaryotic Diversity
      3. 22.2 Structure of Prokaryotes
      4. 22.3 Prokaryotic Metabolism
      5. 22.4 Bacterial Diseases in Humans
      6. 22.5 Beneficial Prokaryotes
      7. Key Terms
      8. Chapter Summary
      9. Review Questions
      10. Critical Thinking Questions
      11. Test Prep for AP® Courses
      12. Science Practice Challenge Questions
  7. Unit 6
    1. 23 Plant Form and Physiology
      1. Introduction
      2. 23.1 The Plant Body
      3. 23.2 Stems
      4. 23.3 Roots
      5. 23.4 Leaves
      6. 23.5 Transport of Water and Solutes in Plants
      7. 23.6 Plant Sensory Systems and Responses
      8. Key Terms
      9. Chapter Summary
      10. Review Questions
      11. Critical Thinking Questions
      12. Test Prep for AP® Courses
      13. Science Practice Challenge Questions
  8. Unit 7
    1. 24 The Animal Body: Basic Form and Function
      1. Introduction
      2. 24.1 Animal Form and Function
      3. 24.2 Animal Primary Tissues
      4. 24.3 Homeostasis
      5. Key Terms
      6. Chapter Summary
      7. Review Questions
      8. Critical Thinking Questions
      9. Test Prep for AP® Courses
    2. 25 Animal Nutrition and the Digestive System
      1. Introduction
      2. 25.1 Digestive Systems
      3. 25.2 Nutrition and Energy Production
      4. 25.3 Digestive System Processes
      5. 25.4 Digestive System Regulation
      6. Key Terms
      7. Chapter Summary
      8. Review Questions
      9. Critical Thinking Questions
      10. Test Prep for AP® Courses
      11. Science Practice Challenge Questions
    3. 26 The Nervous System
      1. Introduction
      2. 26.1 Neurons and Glial Cells
      3. 26.2 How Neurons Communicate
      4. 26.3 The Central Nervous System
      5. 26.4 The Peripheral Nervous System
      6. 26.5 Nervous System Disorders
      7. Key Terms
      8. Chapter Summary
      9. Review Questions
      10. Critical Thinking Questions
      11. Test Prep for AP® Courses
      12. Science Practice Challenge Questions
    4. 27 Sensory Systems
      1. Introduction
      2. 27.1 Sensory Processes
      3. 27.2 Somatosensation
      4. 27.3 Taste and Smell
      5. 27.4 Hearing and Vestibular Sensation
      6. 27.5 Vision
      7. Key Terms
      8. Chapter Summary
      9. Review Questions
      10. Critical Thinking Questions
      11. Science Practice Challenge Questions
    5. 28 The Endocrine System
      1. Introduction
      2. 28.1 Types of Hormones
      3. 28.2 How Hormones Work
      4. 28.3 Regulation of Body Processes
      5. 28.4 Regulation of Hormone Production
      6. 28.5 Endocrine Glands
      7. Key Terms
      8. Chapter Summary
      9. Review Questions
      10. Critical Thinking Questions
      11. Test Prep for AP® Courses
      12. Science Practice Challenge Questions
    6. 29 The Musculoskeletal System
      1. Introduction
      2. 29.1 Types of Skeletal Systems
      3. 29.2 Bone
      4. 29.3 Joints and Skeletal Movement
      5. 29.4 Muscle Contraction and Locomotion
      6. Key Terms
      7. Chapter Summary
      8. Review Questions
      9. Critical Thinking Questions
      10. Science Practice Challenge Questions
    7. 30 The Respiratory System
      1. Introduction
      2. 30.1 Systems of Gas Exchange
      3. 30.2 Gas Exchange across Respiratory Surfaces
      4. 30.3 Breathing
      5. 30.4 Transport of Gases in Human Bodily Fluids
      6. Key Terms
      7. Chapter Summary
      8. Review Questions
      9. Critical Thinking Questions
      10. Test Prep for AP® Courses
      11. Science Practice Challenge Questions
    8. 31 The Circulatory System
      1. Introduction
      2. 31.1 Overview of the Circulatory System
      3. 31.2 Components of the Blood
      4. 31.3 Mammalian Heart and Blood Vessels
      5. 31.4 Blood Flow and Blood Pressure Regulation
      6. Key Terms
      7. Chapter Summary
      8. Review Questions
      9. Critical Thinking Questions
      10. Test Prep for AP® Courses
      11. Science Practice Challenge Questions
    9. 32 Osmotic Regulation and Excretion
      1. Introduction
      2. 32.1 Osmoregulation and Osmotic Balance
      3. 32.2 The Kidneys and Osmoregulatory Organs
      4. 32.3 Excretion Systems
      5. 32.4 Nitrogenous Wastes
      6. 32.5 Hormonal Control of Osmoregulatory Functions
      7. Key Terms
      8. Chapter Summary
      9. Review Questions
      10. Critical Thinking Questions
      11. Test Prep for AP® Courses
    10. 33 The Immune System
      1. Introduction
      2. 33.1 Innate Immune Response
      3. 33.2 Adaptive Immune Response
      4. 33.3 Antibodies
      5. 33.4 Disruptions in the Immune System
      6. Key Terms
      7. Chapter Summary
      8. Review Questions
      9. Critical Thinking Questions
      10. Test Prep for AP® Courses
      11. Science Practice Challenge Questions
    11. 34 Animal Reproduction and Development
      1. Introduction
      2. 34.1 Reproduction Methods
      3. 34.2 Fertilization
      4. 34.3 Human Reproductive Anatomy and Gametogenesis
      5. 34.4 Hormonal Control of Human Reproduction
      6. 34.5 Fertilization and Early Embryonic Development
      7. 34.6 Organogenesis and Vertebrate Formation
      8. 34.7 Human Pregnancy and Birth
      9. Key Terms
      10. Chapter Summary
      11. Review Questions
      12. Critical Thinking Questions
      13. Test Prep for AP® Courses
      14. Science Practice Challenge Questions
  9. Unit 8
    1. 35 Ecology and the Biosphere
      1. Introduction
      2. 35.1 The Scope of Ecology
      3. 35.2 Biogeography
      4. 35.3 Terrestrial Biomes
      5. 35.4 Aquatic Biomes
      6. 35.5 Climate and the Effects of Global Climate Change
      7. Key Terms
      8. Chapter Summary
      9. Review Questions
      10. Critical Thinking Questions
      11. Test Prep for AP® Courses
      12. Science Practice Challenge Questions
    2. 36 Population and Community Ecology
      1. Introduction
      2. 36.1 Population Demography
      3. 36.2 Life Histories and Natural Selection
      4. 36.3 Environmental Limits to Population Growth
      5. 36.4 Population Dynamics and Regulation
      6. 36.5 Human Population Growth
      7. 36.6 Community Ecology
      8. 36.7 Behavioral Biology: Proximate and Ultimate Causes of Behavior
      9. Key Terms
      10. Chapter Summary
      11. Review Questions
      12. Critical Thinking Questions
      13. Test Prep for AP® Courses
      14. Science Practice Challenge Questions
    3. 37 Ecosystems
      1. Introduction
      2. 37.1 Ecology for Ecosystems
      3. 37.2 Energy Flow through Ecosystems
      4. 37.3 Biogeochemical Cycles
      5. Key Terms
      6. Chapter Summary
      7. Review Questions
      8. Critical Thinking Questions
      9. Test Prep for AP® Courses
      10. Science Practice Challenge Questions
    4. 38 Conservation Biology and Biodiversity
      1. Introduction
      2. 38.1 The Biodiversity Crisis
      3. 38.2 The Importance of Biodiversity to Human Life
      4. 38.3 Threats to Biodiversity
      5. 38.4 Preserving Biodiversity
      6. Key Terms
      7. Chapter Summary
      8. Review Questions
      9. Critical Thinking Questions
      10. Test Prep for AP® Courses
  10. A | The Periodic Table of Elements
  11. B | Geological Time
  12. C | Measurements and the Metric System
  13. Index
43.
A pathogenic bacterium has been engulfed by a phagocytic cell as part of the innate immune response. Which of the following illustrations best represents the response? [source: AP Biology Course and Exam Description Fall 2012, p. 132]
44.
How do natural killer cells react to healthy cells compared to cells infected with a pathogen?
  1. Natural killer cells recognize MHC I on a healthy cell and do not kill it, while the infected cells that do not present MHC I are killed.
  2. Natural killer cells recognize MHC I on an infected cell and kill it, while the healthy cells that do not present MHC I are not killed.
  3. Natural killer cells recognize MHC II on a healthy cell and do not kill it, while the infected cells that do not present MHC II are killed.
  4. Natural killer cells recognize MHC II on an infected cell and kill it, while the healthy cells that do not present MHC II are not killed.
45.

The flow diagram shows four boxes connected by arrows. The first box is labeled A and reads: PAMPs. An arrow then leads to the second box labeled B, which reads: PRRs. An arrow then leads to the third box, which reads: Cytokines. An arrow then leads to the fourth box labeled C, which reads: Reduced gene expression, protein synthesis.

The following incomplete diagram represents a series of events during an innate immune response. The labels A, B, and C need to be replaced with the names of the cells involved. Which set of cells correctly completes this diagram?

  1. A = infected host cell, B = pathogen, C = healthy host cell
  2. A = healthy host cell, B = pathogen, C = dendritic cell
  3. A = dendritic cell, B = infected host cell, C = pathogen
  4. A = pathogen, B = dendritic cell, C = healthy host cell
46.
A healthy person produces antibodies to pathogens that invade the body. However, if this person becomes infected with HIV, the body loses the ability to produce antibodies. Research has shown that the virus attacks and destroys CD4+T cells. Why does destruction of CD4+T cells lead to a loss of antibody synthesis in HIV-infected patients?
  1. CD4+T cells are a required intermediate in a series of cell-to-cell signaling events that must be completed before B cells can mature.
  2. CD4+T cells have CD4 molecules covalently bound to their cell surfaces and do not induce apoptosis in other cells during an immune response.
  3. CD4+T cell counts are about 1,000 per microliter in a healthy person, but drop below 400 per microliter in a person who cannot mount an immune response.
  4. CD4+T cell precursors are formed in the bone marrow and then migrate to the thymus, where they develop their T cell receptors.
47.
Which of the following diagrams best illustrates how a macrophage activates a helper T cell (THcell)?
48.

The graph plots antibody titer on the y-axis versus time on the x-axis. An arrow with the label vaccination appears at 0 on the x-axis. A red line labeled IgM shows a dramatic peak at 10–14 days. A blue line labeled IgG shows a much less dramatic arc with its peak at a slightly later time interval.

The graph shows changes in a person’s blood after they receive a vaccination. Explain how cell communication is involved in bringing about the changes depicted in the graph.

  1. The vaccine introduces antigens specific to a pathogen into the person’s blood. These antigens are moved to the cell surface of antigen-presenting cells present in the blood. Receptors on helper T cells bind to the antigens present on the antigen-presenting cell. This direct cell-to-cell contact initiates a series of events that leads to production of antibodies by B lymphocytes.
  2. The vaccine introduces antigens specific to a pathogen into the person’s blood. These antigens bind to the receptors on the surface of T cells. This direct cell-to-cell contact initiates a series of events that leads to production of antibodies by B lymphocytes.
  3. The vaccine introduces antigens specific to a pathogen into the person’s blood. These antigens are moved to the cell surface of antigen-presenting cells present in the blood. This direct cell-to-cell contact initiates a series of events that leads to production of antibodies by B lymphocytes.
  4. The vaccine introduces antigens specific to a pathogen into the person’s blood. These antigens are moved to the cell surface of antigen-presenting cells present in the blood. Receptors on helper T cells bind to the antigens present on the antigen-presenting cell. This direct cell-to-cell contact initiates a series of events that activates the complement system.
49.
B cells are important immune cells that fight infections. How is a naïve B cell stimulated to mature into a plasma cell that secretes antibodies?
  1. T cells secrete cytokines, which help the B cell to multiply and mature into an antibody-producing plasma cell.
  2. Natural killer cells secrete cytokines, which help the B cell to multiply and mature into an antibody-producing plasma cell.
  3. T cells secrete interferons, which help the B cell to multiply and mature into an antibody-producing plasma cell.
  4. Natural killer cells secrete interferons, which help the B cell to multiply and mature into an antibody-producing plasma cell.
50.

The illustration shows bacterial toxins encountering a host cell with toxin receptors. It then shows antibodies bound in complex to the toxins outside of the host cell.

The diagram illustrates a process taking place during an immune response. What process is represented by this diagram?

  1. opsonization
  2. apoptosis
  3. neutralization
  4. complement activation
51.

The flow diagram shows a mouse embryo not making Ig on the left and a mouse B cell tumor making a specific light chain on the right. Arrows from each cell lead to a box that reads: DNA extracted and digested with restriction enzyme. Arrows then point to a box that reads: DNA restriction fragments separated by electrophoresis. Arrows then point to a box that reads: V- and C-region coding sequences visualized by hybridization with radioactive DNA probes. The left arrow then points to an illustration showing V- and C-region coding sequences on separate fragments. The right arrow then points to an illustration showing V- and C-region coding sequences on the same fragment.

Scientists performed an experiment using a cell from a mouse embryo and a B cell from an adult mouse. The mouse embryo cell does not make antibodies, yet its DNA contains nucleotide sequences encoding antibody polypeptides. The adult mouse B cell makes and secretes a single type of antibody. In the experiment, radiolabeled DNA probes were synthesized to be complementary to the DNA encoding the light chains of antibody produced by the adult mouse B cells. Then, DNA from the mouse embryo cell and from the adult B cell were isolated and tested to see if either hybridized with the synthesized radiolabeled DNA probes. The results are shown in the diagram. Which claim is best supported by the data?

  1. The mouse genome contains an enormous number of antibody genes, which accounts for the huge diversity of antibody molecules that can be made.
  2. Rearrangement of gene segments encoding antibody polypeptides occurs at the level of DNA to produce an enormous diversity of antibody molecules.
  3. The tremendous diversity of antibody molecules that can be made results from post-translational modifications of antibody polypeptide chains.
  4. Each antibody is encoded by its own unique gene in the DNA, which explains how antibodies can have different antigen binding properties.
52.
How does an antibody molecule bind specifically to one antigen but not to others?
  1. due to the presence of a specific antigen binding site
  2. due to the constant region
  3. due to diversity of variable region
  4. due to the complete antibody structure
53.
The human genome contains less than 50,000 genes, yet a human has the capability of producing more than 1012different antibody molecules. How can this evidence be used to support the claim that the human body has an immune system that is both effective and efficient?
  1. There are so many different antibody molecules that can be made, each of which can specifically target a particular pathogen to destroy it. This specificity makes the immune system more effective. The immune system is also efficient because each antibody need to have its own gene.
  2. There are so many different antibody molecules that can be made, each of which can non-specifically target a particular pathogen to destroy it. This non-specificity makes the immune system more effective. The immune system is also efficient because each antibody does not need to have its own gene.
  3. There are so many different antibody molecules that can be made, each of which can specifically target a particular pathogen to destroy it. This specificity makes the immune system more efficient. The immune system is also effective because each antibody does not need to have its own gene.
  4. There are so many different antibody molecules that can be made, each of which can specifically target a particular pathogen to destroy it. This specificity makes the immune system more effective. The immune system is also efficient because each antibody does not need to have its own gene.
54.

The illustration shows a mast cell producing histamine. Histamine receptors are shown on vessel cells and nerve cells with anti-histamine bound to the histamine receptors.

An allergy is caused by the immune system reacting to a foreign protein to produce IgE molecules that recognize the protein. These IgE molecules become associated with mast cells that respond to future exposures to the protein by releasing histamines into the body. The diagram shows this release and also shows how a drug called an antihistamine can help an allergy sufferer reduce their allergy symptoms. Which of the following statements explains how an antihistamine helps restore homeostasis during an allergic reaction?

  1. Antihistamines prevent mast cells from becoming associated with IgE molecules that recognize the foreign protein allergen.
  2. Antihistamines prevent mast cells from releasing histamines and causing the unpleasant allergy symptoms.
  3. Antihistamines prevent histamines that have been released by mast cells from stimulating the itching and swelling of body tissues.
  4. Antihistamines prevent mast cells from producing histamines, which halts their effect on the body.
55.

The illustration shows the pituitary gland secreting TSH, which binds to a TSH receptor on a thyroid cell. This then stimulates hormone synthesis and the regulated production of thyroid hormones, which are connected to the pituitary gland under negative feedback control.

The diagram shows the normal feedback loop that controls the production of thyroid hormones in the human body. Graves’ disease is an autoimmune disease in which the body produces autoantibodies to the TSH receptor. When these autoantibodies bind to the receptor, it mimics the action of the TSH hormone. How would the feedback loop and the regulated production of thyroid hormones shown in the diagram be affected in a person with Graves’ disease?

  1. The feedback loop would be disrupted. Autoantibodies would bind to the TSH receptors, allowing them to continue to produce thyroid hormones. As a result, there would be an overproduction of thyroid hormones because the negative feedback system would be unable to function.
  2. The feedback loop would be not be disrupted. Autoantibodies would bind to the TSH receptors, allowing them to continue to produce thyroid hormones. As a result, there would be an overproduction of thyroid hormones because the negative feedback system would be unable to function.
  3. The feedback loop would be disrupted. Autoantibodies would not bind to the TSH receptors, allowing them to continue to produce thyroid hormones. As a result, there would be an overproduction of thyroid hormones because the negative feedback system would be unable to function.
  4. The feedback loop would be disrupted. Autoantibodies would bind to the TSH receptors, allowing them to continue to produce thyroid hormones. As a result, there would be an overproduction of thyroid hormones because the negative feedback system was functional.
56.

Myasthenia gravis is an autoimmune disease that initially presents with muscle weakness and can progress to complete impairment of muscle movement. The diagram compares a healthy individual with an individual suffering from this disease. Which statement best explains what happens to bring about this disease?

  1. The body produces antibodies against nerve cells, which prevents the nerve cells from releasing acetylcholine during signal transmissions to muscle.
  2. The body produces antibodies against acetylcholine, which prevents acetylcholine from transmitting signals from nerves to muscle.
  3. The body produces antibodies against receptors in muscle, which prevents acetylcholine from binding and completing nerve signal transmission.
  4. The body produces antibodies against acetylcholine, which prevents acetylcholine from breaking down after signal transmission is complete.
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