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Biology for AP® Courses

Critical Thinking Questions

Biology for AP® CoursesCritical Thinking Questions
  1. Preface
  2. The Chemistry of Life
    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. The Cell
    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. Genetics
    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. Evolutionary Processes
    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. Biological Diversity
    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. Plant Structure and Function
    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. Animal Structure and Function
    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. Ecology
    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
25.
Apply your understanding of how living organisms use energy to argue in favor of why it is either beneficial or detrimental for cells to use ATP rather than directly using the energy stored in the bonds of carbohydrates to power cellular reactions.
  1. ATP is readily available in the form of a single unit that provides a consistent, appropriate amount of energy. If cells harvested energy from various carbohydrate compounds, they would need to tailor each reaction to each energy source.
  2. ATP energy cannot activate the ROS dependent stress response whereas food molecules are responsible for activating ROS.
  3. ATP is low in energy, but food molecules (in the form of carbohydrates) possess higher levels of energy that cells can use.
  4. ATP is readily available to cells, unlike the carbohydrate compounds that have to first be phosphorylated in order to release their energy.
26.
What role does \text{NAD}^{+} {\!} play in redox reactions?
  1. \text{NAD}^{+} {\!}, an oxidizing agent, can accept electrons and protons from organic molecules and get reduced to \text{NADH}.
  2. \text{NAD}^{+} {\!}, a reducing agent, can donate its electrons and protons to organic molecules.
  3. \text{NAD}^{+} {\!}, an oxidizing agent, can accept electrons from organic molecules and get reduced to NADH2.
  4. \text{NAD}^{+} {\!}, a reducing agent, can donate its electrons and protons to inorganic molecules.
27.

Which statement best explains how electrons are transferred and the role of each species. Remember that R represents a hydrocarbon molecule and RH represents the same molecule with a particular hydrogen identified.

\text{RH} + \text{NAD}^{+} {\!} \rightarrow \text{NADH} + \text{R}
  1. \text{RH} acts as a reducing agent and donates its electrons to the oxidizing agent \text{NAD}^{+} {\!}, forming \text{NADH} and \text{R}.
  2. \text{NAD}^{+} {\!}, the oxidizing agent, donates its electrons to the reducing agent \text{RH}, forming \text{R} and \text{NADH}.
  3. \text{RH} acts as an oxidizing agent and donates electrons to the reducing agent \text{NAD}^{+} {\!}, producing \text{NADH} and \text{R}.
  4. \text{NAD}^{+} {\!}, the reducing agent, accepts electrons from the oxidizing agent \text{RH}, producing \text{NADH} and \text{R}.
28.
Nearly all organisms on Earth carry out some form of glycolysis. Provide an accurate argument that explains how this fact either supports or refutes the assertion that glycolysis is one of the oldest metabolic pathways.
  1. The presence of glycolysis in nearly all organisms indicates that it is an advanced and recently evolved pathway that has been widely used due to the benefits it provides.
  2. Glycolysis is absent in a few higher organisms, which contradicts the assertion that it is one of the oldest metabolic pathways.
  3. Glycolysis is present in some organisms and absent in others. This inconsistency fails to support the assertion that it is one of the oldest metabolic pathways.
  4. To be present in so many different organisms, glycolysis was probably present in a common ancestor rather than evolved many separate times.
29.
Red blood cells (RBCs) do not perform aerobic respiration, but they do perform glycolysis. Provide the reasoning necessary to explain why all cells need an energy source, and predict what would happen if glycolysis were blocked in a sample of RBCs.
  1. Cells need energy to perform cell division. Blocking glycolysis in RBCs interrupts the process of mitosis, leading to nondisjunction.
  2. Cells require energy to perform certain basic functions. Blocking glycolysis in RBCs causes imbalance in the membrane potential, leading to cell death.
  3. Cells maintain the influx and efflux of organic substances using energy. Blocking glycolysis stops the binding of CO2 to the RBCs, causing cell death.
  4. Cells require energy to recognize attacking pathogens. Blocking glycolysis inhibits the process of that recognition, causing invasion of the RBCs by a pathogen.
30.
What is the primary difference between a circular pathway and a linear pathway?
  1. The reactant and the product are the same in a circular pathway but different in a linear pathway.
  2. The circular pathway components get exhausted whereas those of the linear pathway do not and are continually regenerated.
  3. Circular pathways are not suited for amphibolic pathways whereas linear pathways are.
  4. Circular pathways contain a single chemical reaction that is repeated while linear pathways have multiple events.
31.
Cellular respiration breaks down glucose and releases carbon dioxide and water. Which steps in the oxidation of pyruvate produces carbon dioxide?
  1. Removal of a carboxyl group from pyruvate releases carbon dioxide. The pyruvate dehydrogenase complex comes into play.
  2. Removal of an acetyl group from pyruvate releases carbon dioxide. The pyruvate decarboxylase complex comes into play.
  3. Removal of a carbonyl group from pyruvate releases carbon dioxide. The pyruvate dehydrogenase complex comes into play.
  4. Removal of coenzyme A from pyruvate releases carbon dioxide. The pyruvate dehydrogenase complex comes into play.
32.
What three steps are included in the breakdown of pyruvate?
  1. Pyruvate dehydrogenase removes a carboxyl group from pyruvate, producing carbon dioxide. Dihydrolipoyl transacetylase oxidizes a hydroxyethyl group to an acetyl group, producing NADH. Lastly, an enzyme-bound acetyl group is transferred to CoA, producing a molecule of acetyl-CoA.
  2. Pyruvate dehydrogenase oxidizes hydroxyethyl group to an acetyl group, producing NADH. It further removes a carboxyl group from pyruvate, producing carbon dioxide. Lastly, dihydrolipoyl transacetylase transfers enzyme-bound acetyl group to CoA, forming an acetyl-CoA molecule.
  3. Pyruvate dehydrogenase transfers enzyme-bound acetyl group to CoA, forming an acetyl CoA molecule. It then oxidizes a hydroxyethyl group to an acetyl group, producing NADH. Dihydrolipoyl transacetylase removes a carboxyl group from pyruvate, producing carbon dioxide.
  4. Pyruvate dehydrogenase removes carboxyl group from pyruvate, producing carbon dioxide. Dihydrolipoyl dehydrogenase transfers enzyme-bound acetyl groups to CoA, forming an acetyl-CoA molecule. Lastly, a hydroxyethyl group is oxidized to an acetyl group, producing NADH.
33.
Apply your understanding of the various components of the electron transport chain to evaluate how the roles of ubiquinone and cytochrome c differ from those of the other components.
  1. CoQ and cytochrome c covalently bind electrons, while NADH dehydrogenase and succinate dehydrogenase are bound to the inner mitochondrial membrane.
  2. CoQ and cytochrome c are bound to the inner mitochondrial membrane, while NADH dehydrogenase and succinate dehydrogenase are mobile electron carriers.
  3. CoQ and cytochrome c covalently bind electrons, while NADH dehydrogenase and succinate dehydrogenase are mobile electron carriers.
  4. CoQ and cytochrome c are mobile electron carriers, while NADH dehydrogenase and succinate dehydrogenase are bound to the inner mitochondrial membrane.
34.
Consider that the number of ATP molecules formed through cellular respiration varies. Identify the claim that accounts for these differences.
  1. The ATPs produced are immediately utilized in the anaplerotic reactions that are used for the replenishment of the intermediates.
  2. Most of the ATPs produced are rapidly used for the phosphorylation of certain compounds found in plants.
  3. Transport of NADH from cytosol to mitochondria is an active process that decreases the number of ATPs produced.
  4. A large number of ATP molecules are used in the detoxification of xenobiotic compounds produced during cellular respiration.
35.
Which of the following best describes complex IV in the electron transport chain?
  1. Complex IV consists of an oxygen molecule held between the cytochrome and copper ions. The electrons flowing finally reach the oxygen, producing water.
  2. Complex IV contains a molecule of flavin mononucleotide and iron-sulfur clusters. The electrons from NADH are transported here to coenzyme Q.
  3. Complex IV contains cytochrome b, c, and Fe-S. Here, the proton motive Q cycle takes place.
  4. Complex IV contains a membrane-bound enzyme that accepts electrons from FADH2 to make FAD. This electron is then transferred to ubiquinone.
36.
Review the process of fermentation, as illustrated here by lactic acid fermentation. Which of the following statements best compares fermentation and anaerobic respiration and accurately highlights their differences?
  1. Fermentation uses glycolysis, the citric acid cycle, and the ETC but finally gives electrons to an inorganic molecule, whereas anaerobic respiration sues only glycolysis and its electron acceptor is an organic molecule.
  2. Fermentation uses only glycolysis and its final electron acceptor is an organic molecule, whereas anaerobic respiration uses glycolysis, the citric acid cycle, and the ETC but finally gives electrons to an inorganic molecule other than O2.
  3. Fermentation uses glycolysis, the citric acid cycle, and the ETC but finally gives electrons to an organic molecule, whereas anaerobic respiration uses only glycolysis and its final electron acceptor is an inorganic molecule.
  4. Fermentation uses glycolysis and its final electron acceptor is an inorganic molecule, whereas anaerobic respiration uses glycolysis, the citric acid cycle, and the ETC but finally gives electrons to an organic molecule.
37.

What type of cellular respiration is represented in the following equation, and why?

\text{CO}_2 + \text{H}_2 + \text{NADH} \rightarrow \text{CH}_4 + \text{H}_2\text{O} + \text{NAD}^+
  1. Anaerobic respiration, because the final electron acceptor is inorganic.
  2. Aerobic respiration, because oxygen is the final electron acceptor.
  3. Anaerobic respiration, because NADH donates its electrons to a methane molecule.
  4. Aerobic respiration, because water is being produced as a product.
38.
Would you describe metabolic pathways as inherently wasteful or inherently economical? Justify your answer by explaining why you chose it.
  1. Metabolic pathways are wasteful, as they perform uncoordinated catabolic and anabolic reactions that waste some of the energy that is stored.
  2. Metabolic pathways are economical due to the presence of anaplerotic reactions that replenish the intermediates.
  3. Metabolic pathways are economical due to feedback inhibition. Also, intermediates from one pathway can be utilized by other pathways.
  4. Metabolic pathways are wasteful, as most of the energy produced is utilized in maintaining the reduced environment of the cytosol.
39.
Make a claim to identify the lipids that are connected to glucose catabolism pathways, and support your claim with evidence of how the lipids are connected to those pathways.
  1. Glucagon and glycogen can be converted to 3-phosphoglyceraldehyde that is an intermediate of glycolysis.
  2. Chylomicrons and fatty acids get converted to 1,3-bisphosphoglycerate that continues in glycolysis, forming pyruvate.
  3. Sphingolipids and triglycerides form glucagon that can be fed into glycolysis.
  4. Cholesterol and triglycerides can be converted to glycerol-3-phosphate that continues through glycolysis.
40.
Examine and compare the statements below, each of which proposes the specific mechanism by which citrate from the citric acid cycle affects glycolysis. Which statement offers an accurate description of this effect?
  1. Citrate and ATP are negative regulators of hexokinase.
  2. Citrate and ATP are negative regulators of phosphofructokinase-1.
  3. Citrate and ATP are positive regulators of phosphofructokinase-1.
  4. Citrate and ATP are positive regulators of hexokinase.
41.
Why might negative feedback mechanisms be more common than positive feedback mechanisms in living cells?
  1. Negative feedback mechanisms maintain homeostasis whereas positive feedback drives the system away from equilibrium.
  2. Positive feedback mechanisms maintain a balanced amount of substances whereas negative feedback restricts them.
  3. Negative feedback turns the system off, making it deficient of certain substances. Positive feedback balances out these deficits.
  4. Positive feedback brings substance amounts back to equilibrium while negative feedback produces excess amounts of the substance.
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