Table of contents
- 1. Introduction to Biology2h 40m
- 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 41m
- Introduction to Mendel's Experiments7m
- Genotype vs. Phenotype17m
- Punnett Squares13m
- Mendel's Experiments26m
- Mendel's Laws18m
- Monohybrid Crosses16m
- 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 Transport2m
- 35. Soil37m
- 36. Plant Reproduction47m
- 37. Plant Sensation and Response1h 9m
- 38. Animal Form and Function1h 19m
- 39. Digestive System10m
- 40. Circulatory System1h 57m
- 41. Immune System1h 12m
- 42. Osmoregulation and Excretion50m
- 43. Endocrine System4m
- 44. Animal Reproduction2m
- 45. Nervous System55m
- 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
42. Osmoregulation and Excretion
Osmoregulation and Excretion
Problem 15a
Textbook Question
Textbook QuestionWhich process in the nephron is least selective? a. secretion b. reabsorption c. filtration d. passive diffusion of salt

1
Understand the functions of different processes in the nephron: Filtration, reabsorption, secretion, and passive diffusion are all processes that occur in the nephron, each serving a specific role in kidney function.
Define filtration: Filtration in the nephron is the process where blood plasma is forced through the capillaries of the glomerulus into the Bowman's capsule. It is primarily driven by blood pressure.
Analyze the selectivity of filtration: Consider that filtration is based on size exclusion primarily, allowing most solutes smaller than a certain size to pass while retaining larger components like blood cells and large proteins.
Compare with other processes: Reabsorption selectively reclaims substances from the filtrate back into the blood, secretion selectively adds substances from the blood into the filtrate, and passive diffusion involves the movement of substances based on concentration gradients.
Conclude which process is least selective: Determine which process involves the least selectivity in terms of the types or sizes of molecules it handles.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Nephron Function
The nephron is the functional unit of the kidney, responsible for filtering blood and forming urine. It consists of several parts, including the glomerulus, proximal tubule, loop of Henle, distal tubule, and collecting duct. Each part plays a specific role in the processes of filtration, reabsorption, and secretion, which are essential for maintaining fluid and electrolyte balance in the body.
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Functional Groups
Filtration
Filtration is the first step in urine formation, occurring in the glomerulus of the nephron. During this process, blood pressure forces water and small solutes, such as ions and glucose, through the glomerular membrane into the Bowman's capsule, forming the filtrate. This process is relatively non-selective, allowing a wide range of substances to pass while retaining larger molecules like proteins and blood cells.
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Filtration, Reabsorption, and Excretion
Reabsorption and Secretion
Reabsorption and secretion are processes that occur in the renal tubules after filtration. Reabsorption involves the selective uptake of water, ions, and nutrients back into the bloodstream, while secretion is the active transport of additional waste products from the blood into the tubular fluid. Both processes are more selective than filtration, as they regulate the composition of urine and the body's internal environment.
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