Table of contents
- 1. Introduction to Biology2h 42m
- 2. Chemistry3h 40m
- 3. Water1h 26m
- 4. Biomolecules2h 23m
- 5. Cell Components2h 26m
- 6. The Membrane2h 31m
- 7. Energy and Metabolism2h 0m
- 8. Respiration2h 40m
- 9. Photosynthesis2h 49m
- 10. Cell Signaling59m
- 11. Cell Division2h 47m
- 12. Meiosis2h 0m
- 13. Mendelian Genetics4h 44m
- Introduction to Mendel's Experiments7m
- Genotype vs. Phenotype17m
- Punnett Squares13m
- Mendel's Experiments26m
- Mendel's Laws18m
- Monohybrid Crosses19m
- Test Crosses14m
- Dihybrid Crosses20m
- Punnett Square Probability26m
- Incomplete Dominance vs. Codominance20m
- Epistasis7m
- Non-Mendelian Genetics12m
- Pedigrees6m
- Autosomal Inheritance21m
- Sex-Linked Inheritance43m
- X-Inactivation9m
- 14. DNA Synthesis2h 27m
- 15. Gene Expression3h 20m
- 16. Regulation of Expression3h 31m
- Introduction to Regulation of Gene Expression13m
- Prokaryotic Gene Regulation via Operons27m
- The Lac Operon21m
- Glucose's Impact on Lac Operon25m
- The Trp Operon20m
- Review of the Lac Operon & Trp Operon11m
- Introduction to Eukaryotic Gene Regulation9m
- Eukaryotic Chromatin Modifications16m
- Eukaryotic Transcriptional Control22m
- Eukaryotic Post-Transcriptional Regulation28m
- Eukaryotic Post-Translational Regulation13m
- 17. Viruses37m
- 18. Biotechnology2h 58m
- 19. Genomics17m
- 20. Development1h 5m
- 21. Evolution3h 1m
- 22. Evolution of Populations3h 52m
- 23. Speciation1h 37m
- 24. History of Life on Earth2h 6m
- 25. Phylogeny2h 31m
- 26. Prokaryotes4h 59m
- 27. Protists1h 12m
- 28. Plants1h 22m
- 29. Fungi36m
- 30. Overview of Animals34m
- 31. Invertebrates1h 2m
- 32. Vertebrates50m
- 33. Plant Anatomy1h 3m
- 34. Vascular Plant Transport1h 2m
- 35. Soil37m
- 36. Plant Reproduction47m
- 37. Plant Sensation and Response1h 9m
- 38. Animal Form and Function1h 19m
- 39. Digestive System1h 10m
- 40. Circulatory System1h 57m
- 41. Immune System1h 12m
- 42. Osmoregulation and Excretion50m
- 43. Endocrine System1h 4m
- 44. Animal Reproduction1h 2m
- 45. Nervous System1h 55m
- 46. Sensory Systems46m
- 47. Muscle Systems23m
- 48. Ecology3h 11m
- Introduction to Ecology20m
- Biogeography14m
- Earth's Climate Patterns50m
- Introduction to Terrestrial Biomes10m
- Terrestrial Biomes: Near Equator13m
- Terrestrial Biomes: Temperate Regions10m
- Terrestrial Biomes: Northern Regions15m
- Introduction to Aquatic Biomes27m
- Freshwater Aquatic Biomes14m
- Marine Aquatic Biomes13m
- 49. Animal Behavior28m
- 50. Population Ecology3h 41m
- Introduction to Population Ecology28m
- Population Sampling Methods23m
- Life History12m
- Population Demography17m
- Factors Limiting Population Growth14m
- Introduction to Population Growth Models22m
- Linear Population Growth6m
- Exponential Population Growth29m
- Logistic Population Growth32m
- r/K Selection10m
- The Human Population22m
- 51. Community Ecology2h 46m
- Introduction to Community Ecology2m
- Introduction to Community Interactions9m
- Community Interactions: Competition (-/-)38m
- Community Interactions: Exploitation (+/-)23m
- Community Interactions: Mutualism (+/+) & Commensalism (+/0)9m
- Community Structure35m
- Community Dynamics26m
- Geographic Impact on Communities21m
- 52. Ecosystems2h 36m
- 53. Conservation Biology24m
38. Animal Form and Function
Metabolism and Homeostasis
Problem 13`
Textbook Question
Many species of animals on islands are larger than related species on the mainland. Scientists hypothesize that this phenomenon, called island gigantism, evolved in response to the scarcity of competitors and predators on islands. Reduced competition and predation allow species to exploit more resources and free them from the need to hide in small refuges. Which of the following might be a trade-off of gigantism experienced by giant island tortoises?
a. They cool very rapidly during cold weather.
b. It would be difficult to sustain their high mass-specific metabolic rates on a diet of plants alone.
c. It could be more difficult to avoid thermally unfavorable conditions.
d. They could hide from nonnative predators more easily.

1
Understand the concept of island gigantism: Island gigantism is a biological phenomenon where the size of animals on islands is larger compared to their mainland relatives. This is often due to reduced competition and predation, allowing species to grow larger as they exploit available resources.
Consider the potential trade-offs of being larger: While being larger can have advantages, such as increased access to resources and reduced predation, it can also come with disadvantages or trade-offs.
Analyze the options provided: a. Cooling rapidly during cold weather, b. Difficulty sustaining high mass-specific metabolic rates on a plant diet, c. Difficulty avoiding thermally unfavorable conditions, d. Easier hiding from predators.
Evaluate each option in the context of gigantism: Larger animals generally have lower surface area to volume ratios, which affects their heat retention and metabolic needs. Consider how these factors relate to the options.
Identify the most likely trade-off: Larger size could lead to challenges in thermoregulation and metabolic demands, making options b and c more plausible trade-offs. Consider which of these aligns best with the known challenges of large size in animals.

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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Island Gigantism
Island gigantism refers to the phenomenon where animal species on islands evolve to be larger than their mainland relatives. This is often due to reduced competition and predation, allowing species to exploit available resources more freely. The lack of predators and competitors can lead to evolutionary changes that favor larger body sizes, which can be advantageous in resource-rich environments.
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Metabolic Rate
Metabolic rate is the rate at which organisms convert food into energy. Larger animals typically have lower mass-specific metabolic rates, meaning they require less energy per unit of body mass compared to smaller animals. However, sustaining a high metabolic rate on a plant-based diet can be challenging, as plants generally provide less energy compared to animal-based foods, potentially leading to nutritional limitations for large herbivores.
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Thermal Regulation
Thermal regulation is the process by which animals maintain their body temperature within certain limits, despite external temperature changes. Larger animals, like giant tortoises, may face challenges in avoiding thermally unfavorable conditions due to their size, which can make it difficult to find shelter or move quickly to different microclimates. This can be a trade-off of gigantism, as larger body sizes may limit mobility and adaptability to temperature fluctuations.
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