Table of contents

1. Introduction to Biology2h 42m
2. Chemistry3h 37m
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
14. DNA Synthesis2h 27m
15. Gene Expression3h 6m
16. Regulation of Expression3h 31m
17. Viruses37m
- Viruses
  37m
18. Biotechnology2h 58m
19. Genomics17m
- Genomes
  17m
20. Development1h 5m
21. Evolution3h 1m
22. Evolution of Populations3h 53m
23. Speciation1h 37m
24. History of Life on Earth2h 6m
25. Phylogeny2h 31m
26. Prokaryotes4h 59m
27. Protists1h 12m
28. Plants1h 22m
29. Fungi36m
- Fungi
  19m
- Fungi Reproduction
  17m
30. Overview of Animals34m
- Overview of Animals
  34m
31. Invertebrates1h 2m
32. Vertebrates50m
33. Plant Anatomy1h 3m
34. Vascular Plant Transport1h 2m
- Water Potential
  1h 2m
35. Soil37m
- Soil and Nutrients
  20m
- Nitrogen Fixation
  16m
36. Plant Reproduction47m
- Flowers
  33m
- Seeds
  14m
37. Plant Sensation and Response1h 9m
38. Animal Form and Function1h 19m
39. Digestive System1h 10m
- Digestion
  1h 3m
- Blood Sugar Homeostasis
  7m
40. Circulatory System1h 49m
41. Immune System1h 12m
42. Osmoregulation and Excretion50m
- Osmoregulation and Excretion
  50m
43. Endocrine System1h 4m
- Endocrine System
  1h 4m
44. Animal Reproduction1h 2m
- Animal Reproduction
  1h 2m
45. Nervous System1h 55m
- Neurons and Action Potentials
  1h 8m
- Central and Peripheral Nervous System
  46m
46. Sensory Systems46m
- Sensory System
  46m
47. Muscle Systems23m
- Musculoskeletal System
  23m
48. Ecology3h 11m
49. Animal Behavior28m
- Animal Behavior
  28m
50. Population Ecology3h 41m
51. Community Ecology2h 46m
52. Ecosystems2h 36m
53. Conservation Biology24m
- Conservation Biology
  24m

42. Osmoregulation and Excretion

Osmoregulation and Excretion

General Biology

42. Osmoregulation and Excretion

Osmoregulation and Excretion

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2:52 minutes

Problem 1

Textbook Question

Which of the following statements regarding fishes that live in fresh-water is/are correct? Select True or False for each statement.
T/F Water moves across the gills via osmosis until equilibrium is established, at which time the water molecules stop moving.
T/F They lose water to their environment primarily through the gills. They replace this water by drinking.
T/F Water enters epithelial cells in their gills via osmosis. Electrolytes leave the same cells via diffusion.
T/F They have specialized epithelia that actively pump electrolytes from the environment into the blood.

Verified step by step guidance

Understand the concept of osmosis: Osmosis is the movement of water across a semipermeable membrane from an area of low solute concentration to an area of high solute concentration. In biological systems, this process does not stop at equilibrium; rather, water continues to move in both directions at equal rates.

Consider the water balance in freshwater fish: Freshwater fish live in an environment where the water is less concentrated with solutes compared to their body fluids. Therefore, they tend to gain water through osmosis rather than lose it.

Analyze the movement of water and electrolytes in gill epithelial cells: Water enters the cells via osmosis due to the concentration gradient. Electrolytes, however, may leave the cells through diffusion, which is the movement of solutes from an area of high concentration to an area of low concentration.

Examine the role of specialized epithelia in electrolyte regulation: Freshwater fish have specialized cells in their gills that actively transport electrolytes from the environment into their bloodstream to maintain homeostasis, counteracting the passive loss of electrolytes.

Evaluate each statement based on the biological principles discussed: Use your understanding of osmosis, diffusion, and active transport to determine the accuracy of each statement regarding freshwater fish physiology.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Osmosis

Osmosis is the passive movement of water molecules across a semipermeable membrane from a region of lower solute concentration to a region of higher solute concentration. In freshwater fish, osmosis occurs as water moves into the fish's body due to the higher solute concentration inside compared to the surrounding water.

Diffusion

Diffusion is the passive movement of particles from an area of higher concentration to an area of lower concentration. In the context of freshwater fish, electrolytes may diffuse out of the fish's cells into the surrounding water, as the concentration of electrolytes is typically higher inside the fish than in the freshwater environment.

Active Transport

Active transport is the process by which cells move molecules across a membrane against their concentration gradient using energy, often in the form of ATP. Freshwater fish use specialized epithelial cells to actively transport electrolytes from the environment into their bloodstream, counteracting the loss of electrolytes through diffusion.

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