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Biology for AP® Courses

Test Prep for AP® Courses

Biology for AP® CoursesTest Prep for AP® Courses
Table of contents
  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
36 .
Maintaining body heat is important for maintaining body functions in animals. Which of the following statements provides an example of how an animal can actively generate body heat?
  1. Triglycerides are used to store energy for later use.
  2. An animal produces metabolic waste energy in the form of heat.
  3. An animal has insulation, which helps it maintain a constant body temperature.
  4. An animal eats a large amount of high-fat foods to produce adipose tissue.
37 .
Ectotherms and endotherms have different strategies for generating and maintaining body heat. Explain why ectotherms are more dependent on the environment for body heat than endotherms and how endotherms are able to generate and maintain body temperature.
  1. Ectotherms use external thermal heat whereas endotherms use metabolically generated heat to help regulate and maintain body temperatures.
  2. Ectotherms use external heat to help regulate and maintain body temperatures whereas endotherms have constantly varying internal temperatures.
  3. Ectotherms use metabolically-generated heat to maintain a constant body temperature whereas endotherms use metabolically generated heat to regulate body temperature within a wider range.
  4. Ectotherms use external thermal energy to help regulate and maintain body temperatures whereas endotherms maintain a constant body temperature.
38 .
Which of the following statements most directly supports the claim that different species of organisms use different metabolic strategies to meet their energy requirements for growth, reproduction, and homeostasis?
  1. During cold periods, pond-dwelling animals can increase the number of unsaturated fatty acids in their cell membranes, while some plants make antifreeze proteins to prevent ice crystal formation in tissues.
  2. Bacteria lack introns, while many eukaryotic genes contain many of these intervening sequences.
  3. Carnivores have more teeth that are specialized for grinding food.
  4. Plants generally use starch molecules for storage while animals use glycogen and fats for storage.
39 .
(credit: modification of work by Hal Brindley/Travel For Wildlife)

The image shows sizes and masses for different big cats.

Which of the big cats given below would lose heat at the fastest rate?

  1. tiger
  2. lion
  3. leopard
  4. cheetah
40 .
If an American alligator has been basking but gets too hot, how might the alligator cool itself?
  1. increase vasodilation
  2. sweat
  3. move into shade
  4. increase metabolic rate
41 .
(credit: modification of work by Brown, et al./American Journal of Physiology)

The graph shows the core body temperature and metabolic rate during hibernation for a ground squirrel measured over 1 month.

What is a scientific claim that can be done using this data?

  1. Ground squirrels hibernate without interruption.
  2. During hibernation, ground squirrels wake up once every week.
  3. During hibernation, ground squirrels wake up twice a month.
  4. During hibernation, ground squirrels wake up once every ten days.
42 .
Why is hibernation not a good option for small animals like the hummingbirds to help reduce its metabolic rate and conserve its need for food?
  1. Hummingbirds have a fast metabolic rate and a large surface area to volume ratio.
  2. Hummingbirds are unable to lower their metabolic rate and body temperature to enter hibernation.
  3. Hummingbirds migrate south for the winter.
  4. Hummingbirds live a short life.
43 .
How does hibernation differ in small animals such as ground squirrels and larger animals such as bears?
  1. Smaller animals can engage in torpor while larger animals cannot.
  2. Larger animals can engage in torpor while smaller animals cannot.
  3. Smaller animals cannot remain inactive throughout the entire winter while larger animals can.
  4. Larger animals cannot remain inactive throughout the entire winter while smaller animals can.
44 .

This is a 5 by 5 table. The columns are labelled BM (g), CD (min), WU (min), NBT in degrees C, and BTH in degrees C. Bears have a BM of 80,000, a CD of 8307, a WU of 741, a NBT of 37 and a BTH of 33. Marmots have a BM of 4000, a CD of 1766 a WU of 237, a NBT of 40 and a BTH of 18. Honey possums have a BM of 10, a CD of 80, a WU of 24, a NBT of 37 and a BTH of 5. Hummingbirds have a BM of 4, a CD of 59, a WU of 17, a NBT of 40 and a BTH of 2. Shrews have a BM of 2, a CD of 35, a WU of 13, a NBT of 34 and a BTH of 2.

In the data, BM = body mass, CD = cool-down time; WU = warm-up time, NBT = normal body temperature and BTH = body temperature during hibernation. What can you conclude from the data collected on five different animals as shown in the table above?

  1. The time it takes for animals to change body temperature is directly related to body size.
  2. The time it takes for animals to change their body temperature is indirectly related to their size.
  3. Larger animals hibernate for longer periods of time.
  4. Smaller animals hibernate for shorter periods of time
45 .

This is a 5 by 5 table. The columns are labelled BM (g), CD (min), WU (min), NBT in degrees C, and BTH in degrees C. Bears have a BM of 80,000, a CD of 8307, a WU of 741, a NBT of 37 and a BTH of 33. Marmots have a BM of 4000, a CD of 1766 a WU of 237, a NBT of 40 and a BTH of 18. Honey opposums have a BM of 10, a CD of 80, a WU of 24, a NBT of 37 and a BTH of 5. Hummingbirds have a BM of 4, a CD of 59, a WU of 17, a NBT of 40 and a BTH of 2. Shrews have a BM of 2, a CD of 35, a WU of 13, a NBT of 34 and a BTH of 2.

In the data, BM = body mass, CD = cool-down time; WU = warm-up time, NBT = normal body temperature and BTH = body temperature during hibernation.

What is a scientific claim that can be made using this data?

  1. Larger animals have a larger body temperature.
  2. It takes larger animals longer to change their body temperature.
  3. Animals that hibernate have similar body temperatures during hibernation.
  4. It takes smaller animals longer to warm up after hibernation.
46 .
The endocrine system incorporates feedback mechanisms that maintain homeostasis. Which of the following demonstrates negative feedback by the endocrine system?
  1. During labor, the fetus exerts pressure on the uterine wall, inducing the production of oxytocin, which stimulates uterine wall contraction. The contractions cause the fetus to further push on the wall, increasing the production of oxytocin.
  2. After a meal, blood glucose levels become elevated, stimulating beta cells of the pancreas to release insulin into the blood. Excess glucose is then converted to glycogen in the liver, reducing blood glucose levels.
  3. At high elevation, atmospheric oxygen is scarcer. In response to signals that oxygen is low, the brain decreases an individual’s rate of respiration to compensate for the difference.
  4. A transcription factor binds to the regulating region of a gene, blocking the binding of another transcription factor required for expression.
47 .

Flowchart top level shows how low blood calcium levels sensed by parathyroid gland leads to increased parathyroid hormone release at next level, which stimulates calcium absorption by kidneys and intestines and possible breakdown of bone to release calcium if necessary on next level, all of which result in higher blood calcium levels on bottom level.

This figure depicts the process of calcium homeostasis. Describe how blood calcium control is an example of a negative feedback loop.

  1. Cells in parathyroid gland sense calcium decrease causing parathyroid hormone release and stimulating calcium absorption. Bone may also break down to release calcium.
  2. Cells in parathyroid gland sense calcium decrease causing calcitonin release and stimulating calcium absorption. Bone may also break down to release calcium.
  3. Cells in thyroid gland sense calcium decrease causing calcitonin release and stimulating calcium absorption. Bone may also break down to release calcium.
  4. Cells in parathyroid gland sense calcium increase causing parathyroid hormone release and stimulating calcium absorption. Bone may also break down to release calcium.
48 .
(credit: modification of work by Rix I, Nexøe-Larsen C, Bergmann NC, et al./MDText.com, Inc., CC-BY-NC-ND)
Which option describes the variables in the given graphs?
  1. Plasma glucose is the independent variable. Plasma glucagon is the dependent variable.
  2. Plasma glucose and plasma glucagon are both independent variables. Time is the dependent variable.
  3. Plasma glucose and plasma glucagon are both dependent variables. Time is the independent variable.
  4. Plasma glucose is the dependent variable. Plasma glucagon is the independent variable.
49 .
(credit: modification of work by Rix I, Nexøe-Larsen C, Bergmann NC, et al./MDText.com, Inc., CC-BY-NC-ND)

Glucagon is a hormone that plays a role in controlling blood glucose. The graphs show the blood glucose concentration and glucagon concentration in different scenarios. Hyperglycemia is having too much glucose, euglycemia is having normal amounts of it and hypoglycemia is having too little glucose in blood.

Based on this data, what is the role of glucagon?

  1. Trigger the processes that change glucose to other molecules.
  2. Trigger the processes that change other molecules to glucose.
  3. Trigger the processes that get cells to use up more energy.
  4. Trigger the processes that get cells to use up less energy.
50 .
(credit: modification of work by Sarkar J, Potdar AA, Saidel GM/PLoS Computational Biology)

One process that is under the control of a negative feedback loop is red blood cell production. The hormone erythropoietin stimulates production of new blood cells. The graph shows erythropoietin levels after someone donates some blood.

When is the red blood cell production at its maximum?

  1. At day 0 mark.
  2. About 10 days after the blood donation.
  3. About 20 days after the blood donation.
  4. After 40 days after the blood donation.
51 .
Diabetes results when either insulin cannot be produced or does not function properly. Consequently, diabetes can produce complications such as blindness, heart disease, and kidney disease. To help manage diabetes, a patient can get insulin injections. How do insulin injections promote a negative feedback loop to help maintain blood glucose production?
  1. Insulin injections allow transport and storage of glucose to increase blood glucose levels after consuming a large or high-glucose meal.
  2. Insulin injections allow only storage of glucose to decrease blood glucose levels after consuming a large or high-glucose meal.
  3. Insulin injections allow transport and storage of glucose to increase blood glucose levels before consuming a meal.
  4. Insulin injections allow transport and storage of glucose to decrease blood glucose levels after consuming a large or high-glucose meal.
52 .
Positive feedback loops amplify processes in organisms. Which of the following statements describes the role of the hormone oxytocin in a positive feedback loop for childbirth?
  1. Oxytocin halts uterine contractions when the fetus pushes on the uterine wall.
  2. Oxytocin maintains pain levels as the child is pushed through the birth canal.
  3. Oxytocin stimulates uterine contractions when the fetus pushes on the uterine wall.
  4. Oxytocin decreases pain levels as the child is pushed through the birth canal.
53 .
Birth is one of the few positive feedback loops observed in humans and is essential for the proper delivery of babies. Describe how a baby pushing against a pregnant woman’s cervix stimulates a positive feedback loop.
  1. Stretching stimulates nerve impulses to be sent to the brain, which releases oxytocin from the pituitary, which in turn causes uterine contractions.
  2. Stretching stimulates nerve impulses to be sent to the brain, which releases estrogen from the pituitary, which in turn causes uterine contractions.
  3. Stretching stimulates nerve impulses to be sent to the brain, which releases oxytocin from the parathyroid gland, which in turn causes uterine contractions.
  4. Stretching stimulates nerve impulses to be sent to the brain which releases progesterone from the pituitary, which in turn causes uterine contractions
54 .
Negative feedback mechanisms are far more prevalent in the human body than positive feedback loops because they help regulate homeostasis. However, there are some instances of positive feedback loops that can be observed in animals. Regulation of which of the following is an example of a positive feedback loop?
  1. When body temperature gets too high, signals are sent to reduce body temperature.
  2. Increased blood glucose levels stimulate insulin production, which in turn sequesters glucose from the blood.
  3. Decreased calcium levels stimulate increased calcium absorption.
  4. Activation of one clotting factor stimulates production of other clotting factors until a fibrin clot is produced.
55 .
Both negative and positive feedback loops are essential for maintaining proper body functions. Blood calcium and blood clotting are under the control of different feedback loops. Which of these processes is maintained by a positive feedback loop and why?
  1. Blood clotting is maintained by a positive feedback loop, as clotting is amplified in response by increasing the amount of clotting factors when clotting factors are present.
  2. Blood clotting is maintained by a positive feedback loop, as clotting factors are maintained in a specific range and a positive loop helps return the conditions to the set point.
  3. Blood calcium is maintained by a positive feedback loop, as calcium levels are amplified in response by increasing the amount of calcium levels when calcium is present.
  4. Blood calcium is maintained by a positive feedback loop, as calcium levels are maintained in a specific range and a positive feedback loop helps return the conditions to the set point.
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